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Ecology of Tigriopus californicus (Copepoda, Harpacticoida) in Barkley Sound, British Columbia Powlik, James John 1996

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ECOLOGY OF TIGRIOPUS CALIFORNICUS (COPEPODA, IIARPACTICOIDA)IN BARKLEY SOUND, BRITISH COLUMBIABYJames John PowlikB.Sc. (hons.), The University of British Columbia (1988)M.Sc., The University of British Columbia (1990)A THESIS SUBMJTfED IN PARTIAL FULFILLMENTOF THE REQUIREMENTS FOR THE DEGREE OFDOCTOR OF PHILOSOPHYINTHE FACULTY OF GRADUATE STUDIES(Department of Oceanography)WE ACCEPT THIS THESIS AS CONFORMINGHyiT)DTHE UNIVERSITY OF BRITISH COLUMBIAAPRIL, 1996© James John Powilk, 1996In presenting this thesis in partial fhffillment of the requirements for an advanced degreeat the University ofBritish Columbia, I agree that the Library shall make it freely availablefor reference and study. I further agree that permission for extensive copying of thisthesis for scholarly purposes may be granted by the head of my Department or by his orher representatives. It is understood that copying or publication of this thesis for financialgain shall not be allowed without my written permission.2Department of OceanographyThe University ofBritish Columbia1461 - 6270 University Blvd.Vancouver, B.C.CANADA V6T 1Z4Date: ‘ABSTRACTThe thesis addresses several aspects of the habitat characters and populationattributes of the splashpool copepod, Tigriopus californicus (Baker) in Barkley Sound,British Columbia. Overall, 90.1% of pools containing T. californicus were found at 3.0to 5.0 m above lowest normal tide, with an average surface area-to-volume ratio of 7.06.Copepod habitation was found at water temperatures of 6 to 33°C; salinities of less than 1to 139%; hydrogen ion concentrations (pH) of 6.1 to 9.5; and oxygen levels of 1.1 to13.7 mg L1. Vegetation and sediment were sparse in T. californicus pools (15.79 ±10.6% cover in 9.4 ± 11.1 % of pools, mean ± s.E.); with the most common macroalgaeincluding Enteromorpha compressa, Scytosiphon lomentaria and its Ralfsia-lilce alternatephase. Incidental invertebrates and vertebrates that may act as potential agents ofdispersal for T. californicus and its congeners are also listed and discussed relative to theworld-wide biogeography of the genus.In an analysis of the copepod’s association with chlorophytic macroalgae, poolsand laboratory microcosms containing the alga Cladophora trichotoma retained fewersurviving T. calfomicus (18.6 ± 7.3%) compared to treatments containing E. compressa(93.8 ± 5.4%) or without vegetation (95.6 ± 0.1%); the susceptibility of mature T.californicus to a possible crustacean deterrent produced by C. trichotoma may preclude theestablishment of copepod populations. In a second experiment, apparently dead Tigriopuscahfornicus were enlivened following re-hydration with either fresh or sea water, withgravid females and adult males demonstrating the greatest response (10.7 ± 8.5% recoveryoverall).UDevelopment and body length were also compared under conditions representativeof in situ summer (18 - 20°C; 30 - 32% salinity) or winter (10 - 15°C; 20 - 25% salinity)conditions. Total generation time (egg to adult) was 21 days under summer conditions,and 30 days under winter conditions, though no net difference in body length was observed.Clutch size was 20 ± 4.2 eggs at 10- 15°C and 26 ± 8.1 eggs at 18 - 20°C for females inculture; field specimens had a mean clutch size of 23 ± 6.5 eggs in winter (January),increasing to 37 ± 10.2 eggs• clutch1 in summer (July and August). Population densityranged from 217 ± 401.7 individuals . L-1 in winter to 835 ± 1750.6 individuals•L’ in summer, exceeding 20,000 individuals L1 in some pools. A synthesis of theseresults with previous studies is provided, including suggested parameters for estimatingpopulation flux.111TABLE OF CONTENTSAbstract iiTable of Contents ivList of Tables viList of Figures viilAcknowledgments xPublication of Thesis Results xiDedication xiiiINTRODUCTION 1Chapter 1: Habitat characters of Tigriopus calVornicus in BarkleySound, including notes on the potential of several agentsfor the dispersal of splashpool copepodsIntroduction 11Materials and Methods 16Results 18Discussion 26Conclusions 39Chapter 2: The response of Tigriopus calfornkus to chiorophyticmacroalgae, including Cladophora trichotoma KützingIntroduction 40Materials and Methods 43Results 45Discussion 56Conclusions 61Chapter 3: Desiccation resistance in Tigriopus cal(fornicusIntroduction 62Materials and Methods 65Results 67Discussion 72Conclusions 78ivChapter 4: Development, body length, and feeding of Tigriopuscalifornicus in laboratory culture and field populationsIntroduction 80Materials and Methods 81Results 83Discussion 90Conclusions 99Chapter 5: Seasonal abundance and population flux of Tigriopuscalifornicus in Barkley SoundIntroduction 101Materials and Methods 104Results 108Discussion 118Conclusions 128GENERAL DISCUSSION 130LITERATURE CITED 147APPENDIX A: Locations Maps 161APPENDIX B: Weather and Tide Data 168APPENDIX C: Supplemental Data 182VLIST OF TABLES1.1 Representative studies of Tigriopus field populations and their location 121.2 Abiotic conditions of Barkley Sound splashpools 191.3 Biotic conditions of Barkley Sound splashpools 201.4 Incident meiofauna and macrofauna in Baridey Sound study sites 252.1 Summary of in situ conditions for pool containing Tigriopuscalifomicus pools in Barkley Sound 472.2 Five-day microcosm response of Tigriopus californicus to the presenceof algal material 533.1 Tigriopus californicus response following re-hydration of driedsubstrate material with either rain water or filtered sea water 683.2 Net increase in Tigriopus californicus life-history stages after one weekof observation 693.3 Differentiation of Tigriopus californicus as potential re-colonizers ofhydrated pools 754.1 Development of Tigriopus californicus in laboratory culture 844.2 Food items used for culture of Tigriopus congeners 925.1 Seasonal Tigriopus calfomicus abundance, differentiated bygeneralized life-history stage 1105.2 Parameters used for the calculation of in situ population growth anddecline of Tigriopus californicus populations 1115.3 One week abundance and age structure predicted for Tigriopuscalifornicus founding populations 1125.4 Five week abundance and age structure predicted for Tigriopuscaljfornicus founding populations 1135.5 Instantaneous growth, birth, and death rates for founding populations. 114LIST OF TABLES (continued)B.1 Rainfall at Bamfield (in mm) 1973-1986 169B.2 Summary of key weather conditions during sampling intervals 171B.3 Tide conditions in Barkley Sound during sampling 172B.4 Tide conditions at Friday Harbor, Washington 181C. 1 Summary of pool conditions 184C .2 Summary of avian specimens examined 200C.3 Pearson Product Moment correlation of Tigriopus californicus life-history stage vs. density, temperature, salinity, and tidal elevation. . .. 202C.4 Spearman Rank Order correlation of elevation, temperature, salinityand population density vs. Tigriopus californicus life-history stage.... 204C,5 Spearman Rank Order correlation of Tigriopus ca4fornicus life-historystage pairwise comparisons 206C.6 Two-way Analysis of Variance of TigrEopus cabjornicus abundancewith season and site location 207C.7 Student-Newman-Keuls multiple comparisons for seasonal TigrEopusca4fornicus abundance 208C.8 Student-Newman-Keuls multiple comparisons for locational Tigriopusca1fornicus abundance 209C.9 Temperature and salinity replicate measures 210viiLIST OF FIGURES1.1 Area of study 171.2 Seasonal elevation of splashpools containing Tigriopus californicusrelative to mean water level 211.3 Current patterns of the NE Pacific Ocean 352.1 Response of Tigriopus californicus field populations to the presence ofsplashpool macroalgae 522.2 Tigriopus californicus response following inoculation of Cladophoratrichotoma pools 542.3 Tigriopus cahfornicus response to the presence of Cladophoratrichotoma in laboratory microcosms 553.1 Life-history stage response to hydration in laboratory culture 704.1 Seasonal brood size of Tigriopus cahfornicus 874.2 Overall body length of Tigriopus calfornicus at 18 - 20°C; 100%Sea Water 884.3 Overall body length of Tigriopus californicus at 10 - 15°C; 65%Sea Water 895.1 Calculated versus observed change in Tigriopus californicus density 1155.2 Frequency of copepod extinction with location 1165.3 Frequency of copepod extinction with tidal elevation 117GD.1 Proposed dispersal routes of Tigriopus congeners by avian carriers 141A.1 Location of study pools on Diana Island 162A.2 Location of study pools on First Beach 163A.3 Location of study pools on Helby Island 164vmLIST OF FIGURES (continued)A.4 Location of study pools on Second Beach 165A. 5 Location of study pools on Wizard Islet 166A.6 Location of supplemental study pools on San Juan Island, Washington 167B. 1 Seasonal sampling intervals in 1994 and 1995 170C. I Generalized splashpool basin types 183C.2 Ten-minute splashpool temperature and salinity flux at Friday Harbor 212C.3 Ten-minute splashpool temperature and salinity flux at Cattle Point 213C.4 Hourly splashpool temperature and salinity flux at Friday Harbor. .. 214C .5 Hourly splashpool temperature and salinity flux at Cattle Point 215C.6 Six-hour splashpool temperature and salinity flux at Friday Harbor 216C.7 . Six-hour splashpool temperature and salinity flux at Cattle Point 217C. 8 Twelve-hour splashpool temperature and salinity flux at Cattle Point. . 218ixACKNOWLEDGMENTSThe Auu ay alit Indian Band are duly thanked for providing access to the field sitesaround southeastern Barkley Sound. K. Ailcock and M. N. Madryga assisted with thecollection of data and Dr. G. R. Graves and L. Rimmer provided access to archivedmaterials.I would also like to thank my research advisory committee: Drs. P. G. Harrison, P. J.Harrison, T. F. Pedersen, C. Rankin, and F. J. R. Taylor of the University of BritishColumbia. I am especially indebted to my research supervisor, mentor and good friend,Dr. A. G. Lewis, for his continued guidance, patience, and invaluable support in helpingto inspire, to steer, then see to safe harbor this academic vessel.Finally, I thank Una for ultimately making this manuscript possible. To this day, she isgreatly missed.ames J. PowlikxPUBLICATION OF THESIS RESULTSPortions of this dissertation are currently in press or under review for publication. As ofthis writing, the status and authorship of these manuscripts is as follows:Chapter 1 - portions of Chapter 1 (habitat characters) have been submitted to theJournal ofPlankton Research (U.K. - D. H. Cushing, editor) as:Powlik, J. J. and A. G. Lewis. (submitted) Habitat characters of Tigriopuscalifornicus (Copepoda: Harpacticoida) in Barkley Sound, British Columbia.A. G. Lewis is included as second author of this manuscript as the researchsupervisor of the candidate. The manuscript itself was entirely compiled,written and edited by the candidate, who is listed as the senior author.Chapter 2- is in press with Estuarine, Coastal and ShelfScience (U.S.A.- S. D. Suiltin,editor) as:Powlik, I. J., A. G. Lewis, and N. Verma. (in press) The response of Tigriopuscalifornicus (Copepoda: Harpacticoida) to chlorophytic macroalgae, includingCladophora trichotoma KUtzing. Est. Coast. ShelfSd.A. G. Lewis is included as second author of this manuscript as the researchsupervisor of the candidate. N. Verma provided some preliminary data onnauplii response using methods proposed by the senior author. These datawere reviewed and repeated by the senior author. The manuscript itself wasentirely compiled, written and edited by the candidate, who is listed as thesenior author.Chapter 3- is in press with Estuarine, Coastal and Shelf Science (U.S.A.- S. D. Suilcin,editor) as:Powlik, J. J. and A. G. Lewis. (in press) Desiccation resistance in Tigriopuscalifornicus (Copepoda: Harpacticoida). Est. Coast. Shelf Sci.A. G. Lewis is included as second author of this manuscript as the researchsupervisor of the candidate and as an editor of an early draft of themanuscript. The manuscript itself was entirely compiled and written by thecandidate, who is listed as the senior author.(continued)xiChapter 4 - is in press with Crustaceana (The Netherlands- J. C. von Vaupel Klein,editorial secretary) as:Powlik, J. J., A. G. Lewis, and M. Spaeth. (in press) Development, body length, andfeeding of TigrEopus calfornicus (Copepoda: Harpacticoida) in laboratory cultureand field populations. Crustaceana.A. G. Lewis is included as second author of this manuscript as the researchsupervisor of the candidate. M. Spaeth advised on the preparation of slidesand culture maintenance, and provided several illustrations used as referenceto the text material. The manuscript itselfwas entirely compiled and writtenby the candidate, who is listed as the senior author.Chapter 5 - portions of Chapter 5 (population data) have been submitted to the JournalofPlankton Research (U.K. - D. H. Cushing, editor) as part of the manuscript indicatedunder Chapter 1 above.I hereby verif’ the above information as accurate and provide my permission for inclusionof this mate ‘al in th fol ing thesis.__________________________James J. PowlikAs the co-author of the work indicated above and the research supervisor of thecandidate, I hereby authorize the inclusion of this material in the following thesis, andconfirm tt it does not conflict th the requirements of this thesis or the program ofstudy rth ca te._ _Alan G. Lewis16 March, 1996The University of British ColumbiaxiDedicated to Diana, Goddess of the tides.Thank you for letting me explore, and play awhile in your back yard.And for letting me live.Also dedicated in memory of Mr. John D. G. Boom,nearly as responsible for the completion of this thesis as its author.And to whom Diana was far less forgiving.xliiINTRODUCTION“A bird can roost but on one branch.A mouse can drink but its fill from a river.”— CHINESE PROVERBSince the inception of the discipline, the acicular yet deceptively simple observationthat “no species lives everywhere” has been a fhndamental impetus for the study ofecology. Through empirical manipulative and mensurative study, community structure andthe interactions among their constituents have been investigated in terms of niche breadth(MacArthur, 1968; Coiwell and Futuyma, 1971), biotic and abiotic disturbance (Dayton,1971; Woodin, 1978; Sousa, 1979), species diversity and competition (Connell, 1961,1972; Menge, 1976; Connell, 1978; Underwood, 1981; Bengtsson, 1986), herbivory orpredation (Menge, 1976; Lubchenko, 1978; Coull and Wells, 1983; Valiela, 1984), to listonly a few representative studies. The littoral zone of marine and estuarine ecosystems hasbeen compared to tropical rainforests and coral reefs in terms of species diversity andhabitat complexity, and perhaps even surpasses those comparisons when considered as theinterface between two fluid media of vastly different physical properties. Among allvarieties of ecosystem, the rocky intertidal zone demonstrates a uniquely intimate andcomplex association between biota and the habitat they occupy.A number of studies have sought to designate and differentiate intertidal pools,using a variety of criteria, including; frequency of tidal flushing (Igarashi, 1959),macroflora (Kain, 1958; Gustavsson, 1972; Dethier, 1984), diatoms (Metaxas and Lewis,1992), copepocls (Fraser, 1936a), and fish (Green, 1971; Mgaya, 1992). Other examplesare provided in the review of Metaxas and Scheibling (1993), including the observation ofIIntroduction 2Underwood (1981) that littoral pools may not even be considered true intertidal habitats,since the organisms within them remain immersed following the tide’s ebb.Despite the ease of shoreline access, discrete volume and comparative isolation ofthese “aquaria by the sea” as vessels for the study of microscale ecological processes, theinteractions within littoral and supralittoral pools can compare in complexity to that ofmuch larger ecosystems. Metaxas and Scheibling (1993) caution that care must be taken inselecting ‘replicates’ among tidal pools, since differences in elevation, exposure to wavesplash, pool volume, shading, allochthonous debris, geochemistry, or fresh water influx canvary substantively, even among pools a only few meters apart. Ganning (B., 1971), Green(1971), and Morris and Taylor (1983) are among numerous studies documenting thephysico-chemical conditions in intertidal pools; thermal or haline stratification, oxygen, pH,and carbon dioxide can vary widely among pools or within a single pool, and may fluctuateon an hourly basis, depending on the pool size, volume, atmospheric conditions andbiological activity. Markedly different habitat characters can also be expected based on thefrequency of tidal immersion of the pool, and whether it is considered a sublittoral, littoral,or supralittoral habitat.THE STJPRALITTORAL ZONEThe current thesis uses the definition of Kozloff (1983, p. 198), which marks thelower limit of the supralittoral fringe at 1.8 m above mean lowest low water (MLLW or0.0 m) in California and 2.1 to 2.4 mm Washington and on Vancouver Island. Thisdiscrepancy is due to the increased amplitude of the tides; at more northerly latitudes alongthe Pacific coast of North America, highest tides may reach 3.7 m, compared to tidalmaxima of 2.5 m in central and northern California. I will also use the definitions ofMetaxas and Scheibling (1993) to distinguish between tide pools (large volume waterdeposits experiencing regular or semi-regular flushing by tidal activity), rockpools (smallwater deposits associated with fresh water systems), and splashpools (small sea waterIntroduction 3deposits of higher elevation, hence isolated from regular tidal influence), with the latterterm being most applicable to the current study. As will be discussed, supralittoralsplashpools are quite distinct from the larger, bowl-shaped tide pools found lower in thelittoral zone, carpeted with algal crusts and anemones and home to much more abundantand diverse assemblages of motile organisms; the image of the “typical” tide pooi.Supralittoral pools may be replenished with sea water only by wave splash, wavesassociated with storm events, and the highest tide conditions, which may be extant onlyone or two days per tidal cycle (Egloff, 1966; Dybdahi, 1994). Indeed, given thecomparatively high shoreline position and smaller volume of these pools, organisms withinthem may be impacted more significantly by atmospheric than oceanographic conditions.Whether to designate pools as emergent or semi-emergent substrata is certainly less inquestion for supralittoral pools, which may evaporate completely within a few days or evena few hours, only to be flooded anew by wave activity or runoff.Within habitats, patterns of organism disthbution can be attributed to physical,biological, and chemical factors. The magnitude and influence of each of these will varyaccording to location, season, and the innate tolerance and resilience of the organismsconsidered. The influences particularly applicable to supralittoral meiofauna aresummarized briefly below.Physical Influences: Among sessile or encrusting organisms, disturbance of therocky intertidal zone (as by log strikes or exposure to waves) serves to open new areas forrecruitment and colonization, and checks the monopolization of space by competitivelydominant organisms (e.g., Dayton, 1971; Sousa, 1979; Paine and Levin, 1981). Amongother abiotic influences, fluid circulation is an effective influence in the active or passiveredistribution of organisms, particularly small or planktonic life-history stages, andsupralittoral pools may be equally influenced by atmospheric circulation (wind, intenseprecipitation) as by oceanographic processes (wave splash, longshore transport). AmongIntroduction 4rockpool Crustacea, Brown and Gibson (1983) provide the example of dormant egg stagesof the brine shrimp Artemia, redistributed by wind following the evaporation of rockpools.Igarashi (1959) similarly found an inverse relationship between the frequency of tidalinundation and the age and stability of Tigriopusjaponicus. Fraser (1936a) includedphysical influences among the explanation for his observation that the diversity of copepodspecies on rocky shores was highest at intermediate elevations, but copepod density washighest in largely monospecific populations of Tigriopus fulvus entrenched in hospitablesupralittoral pools.Biological Influences: Competitive interaction for space is the predominantbiological process structuring rocky shore communities (e.g., Connell, 1961; Menge, 1976;Underwood, 1981). The characteristic patterns of zonation observed on rocky shores isoften established by the physiological tolerances of the organisms involved, notably benthicmeio- and macrofauna (recent examples include Dethier, 1982; Huggett and Griffiths,1986; Kooistra et al., 1989; Metaxas and Scheibling, 1993). In isolated, small volumesupralittoral pools, microscale processes including respiration, photosynthesis, andbacterial activity may more significantly determine the immediate conditions of the pool(Morris and Taylor, 1983). Higher on the shore, anthropogenic inputs, or nitrificationfrom guano or the excreta of shoreline vertebrates may also affect biological activity withinpools (e.g., Gaffing and Wulff, 1969), while organic debris deposited by storm activitymay alter significantly the detrital material available for reduction by bacteria.Chemical Influences: Chemical signaling in crustacea has been discussed byKatona (1973) for Eurytemora affinis and E. herdmani; by Griffith and Frost (1976) forCalanuspacificus and Pseudocalanus sp.; and by Gleeson et al. (1987) forPseudodiaptomus coronatus. Bozic (1975) experimentally described an “aggregationpheromone” in Tigriopus (I assume fulvus), and Lazzaretto et al. (1990) proposed a similarspecies-specific agent in the congeners T. flulvus, T. californicus and T. brevicornis thatIntroduction 5allowed the copepods to locate previously inhabited vessels. These authors furthersuggested that the small size and (they assumed) poor sensory development of copepodsmay lead to their reliance on chemical signaling; Dethier (1980) suggested that Tigriopus(californicus) may even use such chemical emissions to relocate to previously-colonizedpools following wash out by wave splash. Suspended in the water column, however, Isubmit that the ability of the copepods to detect or respond to such stimuli under dynamic,wave-washed conditions may be significantly constrained.THE GENUS TIGRIOPUSThere are approximately 2800 described species within the order Harpacticoida,one of seven divisions of the class Crustacea, subclass Copepoda. The genus TigriopusNorman 1868 is one of 9 genera and 80 species within the family Harpacticidae, itself oneof 34 families of the Harpacticoida. Of these 34 families, 17 encompass 93% of the generaand 88% of the species (Coull, 1982). Currently, there are seven recognized species withinthe genus Tigriopus, consisting predominantly of Pacific species Tigriopus calfornicus(Baker 1912) and T. japonicus Mon 1938, and the Atlantic/Mediterranean species T.brevicornis (0. F. MUller 1776), T. fulvus (Fischer 1860) and T. minutus Bozic 1960.Congeners in the southern hemisphere include T. angulatus Lang 1933 and T. raki(Bradford 1967) from records in New Zealand, and several varieties of Tigriopus havebeen reported, particularly in the European literature. Monk (1941) is generally attributedwith establishing the taxonomy of T. californicus, which had been reported previously asTisbe californica (Baker, 1912) and Tigriopus triangulus (Campbell, 1930).Over the past four decades, a legion of studies have used Tigriopus congeners for awide variety of laboratory studies. Experimental use of T. californicus alone includesstudies in feeding and nutrition (Provasoli et aL, 1959; Lear and Oppenheimer, 1962;Anderson and Stephens, 1969), sex determination (Vacquier, 1962; Vacquier and Belser,1965), tolerance to thermal or haline shock (Ranade, 1957; Huizinga, 1971; Kontogiannis,Introduction 61973), osmoregulation and physiology (McDonough and Stiffler, 1981; Goolish andBurton, 1988, 1989), reproduction (Burton, 1985), genetics (Ar-rushdi, 1958; Battaglia etaL, 1978; Burton and Feldman, 1981; Burton and Swisher, 1984; Burton, 1990; Brown,1991), evolution (Burton, 1986; Palmer et aL, 1993), histology (Sullivan and Bisalputra,1980), use as bioassay organisms (Syvitski and Lewis, 1980; Shaw, 1994), tolerance topollutants (Kontogiannis and Bamett, 1973; O’Brien et a!., 1988), and suitability as a foodsource for fish stocks (Morris, 1956; Fahey, 1964). While a discussion of all suchapplications is beyond the scope of the current thesis, studies addressing the field ecologyof Tigriopus species are far less numerous, and will be discussed in Chapter 1.Conclusive morphological or behavioral distinctions have not been established, andexperimental comparisons between species (Battaglia et al., 1978; Lazzaretto et al., 1990)or distant populations of the same species (Burton, 1990, for T. californicus) appear to atleast produce viable Fl progeny. As will be discussed in later chapters, all Tigriopuscongeners demonstrate a high resilience to changes in temperature and salinity (Ranade,1957; Huizinga, 1971; Kontogiannis, 1973), and resistance to anoxic or pollutedconditions (Fraser, 1935; Kontogiannis and Barnett, 1973; O’Brien, 1988). Indeed, muchof the “speciation” among Tigriopus congeners has been based on little more than thezoogeography of the organism or minute differences in morphology; a comprehensiveevaluation of inter-specific reproductive compatibility among Tigriopus congeners has notbeen published (but see Bozic, 1960; Lazzaretto et al., 1990).Distribution ofTigriopus Congeners: Published accounts of the geographic rangeof Tigriopus species are notoriously anecdotal or vague in their description, and details ofthe in situ habitat conditions and collection methods used are often abbreviated inpublished reports. Belser (1959, p. 58) describes Tigriopus as a nearly ubiquitousinhabitant of rocky shorelines, “bordering every ocean of the world,” but this assertion isprobably generous. Obviously, any described range refers only to the areas within which aIntroduction 7given species has been collected and correctly identified. Further, the mere occurrence ofan organism in a given region does not provide evidence that the organism is adequatelyexploiting the resources of this habitat, nor sustaining itself within it.Tigriopus californicus is typically described as occurring from Baja, California, toAlaska, along the Pacific coast of North America (Belser, 1959; Dethier, 1980). The rangeof T. brevicornis is generally taken to be the northeast Atlantic coast of Europe, includingthe British Isles (Clark, 1968; Harris, 1973), Iceland, Norway, Normandy, Monaco andSpain (Belser, 1959). Belser (1959) and Bozic (1960) describe the range for what ispresumably the conspecifics T. fulvus and T. minutus as the Bay of Naples eastward intothe Adriatic Sea. Bradford (1967) clarified descriptions of T. angulatus in New Zealandfrom records of T. californicus (and possibly Harpacticus brevicornis as far south as theAntarctic Peninsula), and provided an account of a second congener in the southernhemisphere, Tigriopus raki.THE EFFECT OF HABiTATFor short-lived organisms, variability in resource selection and life-historyparameters may act to provide a greater ‘bet hedging’ against environmental fluctuations(lain, 1979). As suggested by Bryant (1974) for Drosophila, as much a 70% ofgeographic variation in heterozygosity could be produced by fluctuation in environmentalvariables. By extension to the “marine fruit fly” Tigriopus californicus, it is not surprisingthat the organism exhibits such an apparently high degree of plasticity in its tolerance tophysical exiremes and fluctuations in environmental conditions. Given the minute size ofthe organism against the highly dynamic and ilTegular features of the rocky intertidal shore,Introduction 8it is also not surprising that there is such an apparent restriction in gene flow betweenTigriopus metapopulations’ (discussed in Burton, 1986; Brown, 1991).The question therefore remains: to what extent has T. californicus exploited itscomparatively empty high-tide niche, and to what extent is it limited from other areas?Despite the popularity of the genus as the subject of scientific study, comparatively fewstudies have clearly defined the conditions under which the organism thrives in situ, theextent of its endemic range, and the agents that act to restrict or extend these parameters.The influence of these agents of dispersal may not be incidental to interpret andexplain the observed distribution of Tigriopus congeners throughout the world, but thisaspect of the organism’s natural history has not been previously described, nor fully tested.While the current thesis also does not test experimentally the influence of the variousabiotic and biotic dispersal agents available to T. californicus in Barkley Sound, it doesprovide a list of such agents, and a discussion of their potentiality (see Chapter 1).THESIS OBJECTIVES AND PRESENTATIONUsing the habitat and population flux of T. calfornicus as specific exemplars, thisthesis will detail several aspects of the supralittoral community within the context of thefollowing four objectives:1. To describe quantitatively the seasonal habitat characters of T. californicus in BarkleySound, the distribution of the copepod within this habitat, and the potential in situflux of the immediate environmental parameters. Clearly such a description isessential to place into proper context the conditions and results of both laboratoryand field experimentation, yet a satisfactory account of the organism’s supralittoralhabitat has not previously been published.Sensu Gilpin and Hanski (1991), a metapopulation is a collection of local populations linked bydispersal. As used by Dybdahl (1994), such an assemblage may also be subject to frequent extinctionevents.Introduction 92. To elucidate the mechanisms by which T. caljfornicus resists the effects of exposure inephemeral splashpools, including the co-incidence of vegetation (Chapter 2), and theability of the organism itself to resist desiccation (Chapter 3). While macrofauna mayprovide either refugia or a surface for the growth of nutritive microflora for 7’.californicus, the genera of seaweeds and patterns of co-incidence or exclusion in T.californicus pools have not been established. Secondarily, while accounts of theorganism’s response (as to pollutants or physiological tolerance) has been broadlyestablished under experimental conditions, few of these experiments have beenconducted under conditions truly representative of supralittoral splashpools.3. To discuss the potential of several dispersal agents to produce the observed distributionof Tigriopus species. As an organism with the innate physiological tolerance to liveanywhere in the littoral zone, why is the organism apparently ‘restricted’ tosupralittoral pools? And if so constrained, why is the global distribution of the genusso ubiquitous in temperate splashpools? A listing of such agents, related to thesupralittoral habitat and considerate of the copepod’s innate tolerance, has also notpreviously been published.4. To describe the development of T. californicus and offer revised parameters forestimating the flux of T. californicus populations. Although a number of studieshave discussed the generation time and fecundity of laboratory cultures of Tigriopusspecies (e.g., Huizinga, 1971; Burton, 1985; Kahan et al., 1988), a clear descriptionof the life-history of T. californicus based on in situ observations and theenvironmental considerations introduced above is not currently available.The thesis proposes to address the above objectives within the context of a seriesof mensurative and manipulative studies. These fmdings will be presented in the followingorder:Introduction 101. A quantified description of the supralittoral habitat of T. californicus in Barkley Sound,including the predominant shoreline conditions, seasonal flora and fauna, and basicwater conditions. A census of biotic and abiotic agents that may act to cull orredistribute the copepod is also provided (Chapter 1);2. An experimental analysis of processes that occur within isolated pools, specifically theobserved association of T. californicus with certain predominant macroalgae(Chapter 2), and the copepod’s innate resistance to desiccation during intervals ofcomplete or nearly complete evaporation (Chapter 3);3. An unprecedented description of T. calfornicus’ development in laboratory culture, andnotably, under temperature and salinity regimes truly representative of in situconditions (Chapter 4); and4. Presentation of data on the population density and age structure within T. californicuspools throughout the year. Finally, based on the observations in Chapters 1 through4, an attempt is made to estimate the growth, decline, and frequency of extinction forT. californicus populations over approximately a single generation (Chapter 5).In following these objectives, and sequence of presentation, the current thesis willseek to contribute several explanations to the overarching ecological question: why isTigriopus calfomicus not found “everywhere” among the various aquatic biotopes. Thechapters that follow provide a series of field and laboratory experiments that purport,firstly, to define the habitat characters and shore-bound limits of the organism; secondly, toidentify the agents which potentially act to restrict or extend this range; and finally,describe the intrinsic ability of the organism to procreate and propagate its numbers withinthe constraints of its habitat.CHAPTER 1: HABiTAT CHARACTERS OF TIGRIOPUS CALIFORNICUS IN BARKLEYSOUND, INCLUDING NOTES ON THE POTENTIAL OF SEVERAL AGENTSFOR THE DISPERSAL OF SPLASHPOOL COPEPODS.I1TRODUcrION“Whether Tempter sent, or whether tempest tossed thee here ashore,Desolate yet all undaunted, on this desert land enchanted —“— EDGAR ALLEN POE, 1845Since the earliest descriptions of Tigriopus copepods (MUller, 1776; Norman,1868), constituents of this genus have become subjects familiar to a variety ofmensurative and manipulative studies in harpacticoid copepod biology (Fraser, 1936a,1936b; Provasoli et aL, 1959; Lear and Oppenheimer, 1962; Huizinga, 1971; Harris,1973; Battaglia et al., 1978; Dethier, 1980; Burton and Feldman, 1981; Kahan et al.,1988). From Belser (1959), Tigriopus copepods are found on the supralittoral fringes ofnearly every world ocean, including the shores of Japan (Tigriopus japonicus), NorthernEurope (T. brevicornis), the Adriatic (T. fulvus and T. brevicornis), and North America(T. californicus).The Habitat of Tigriopus CopepodsDespite being heralded as an oceanic “white rat” (Belser, 1959) or “marine fruitfly” (Dethier, 1980) for their innate physical tolerance and ease of culture in laboratorystudy, substantive field studies of Tigriopus spp. are few in number (Table 1.1).Uniformly, these studies omit critical details of the habitat in which the organism lives;in laboratory studies, methods of copepod collection are similarly abbreviated, and11Chapter 1: Habitat and Environmental conditions 12TABLE 1.1. Representative studies of Tigriopus field populations and their location.Tigriopus cal!fornicus Other Tigriopus speciesStudy Location Study LocationBaker, 1912 Laguna Beach, T. fulvusCalifornia Fraser, 1936a,b Port St. Mary,U.K.Monk, 1941 (California) Bozic, 1960 (Europe)Egloff, 1966 Mussel Giove, Carli et al., 1984 (Spain)CaliforniaVittor, 1971 Charleston,OregonI’. brevicornisDethier, 1980 San Juan Island, Comita and Comita, Isle of Cumbrae,as ngton 1966 (samples from) ScotlandBurton et al., 1979 Bodega Bay, Clark, 1968 (British Isles)Moss Beach,California Harris, 1973 Plymouth, U.K.Burton and Los Angeles,Feldman, 1981 CaliforniaDybdahi, 1989 Bodega Bay,CaliforniaBrown, 1991 Bodega Bay, T japonicusCalifornia Igarashi, 1959, 1960 (Japan)Dybdahl, 1994 Bodega Bay, Koga, 1970 Fukuoka,California JapanTakano, 1971 Sagarni Bay,JapanPowlik and Lewis Barkley Sound,(current and in Britishpress) ColumbiaChapter 1: Habitat and Environmental Conditions 13considered extraneous to the subsequent use of the cultured organism. Studies of in situconditions have included discussions of population age and stability with tidal influence(Igarashi, 1959), sex ratio (Egloff, 1966), adaptive strategy (Vittor, 1971), the influenceof predation (Dethier, 1980) and metapopulation dynamics (Dybdahl, 1994). Tigriopusspp are routinely described as ‘restricted’ to the supralittoral zone of rocky shores (2.4 to4.1 m above lowest normal tide, sensu Kozioff, 1983). A typical habitat description ishere excerpted from Lear and Oppenheimer (1962, p. lxiii):“Tigriopus cahfornicus grows only.,. in pools above the high-tide mark anddependent upon splash for sea-water replenishment. This environment ischaracterized by extreme fluctuations of temperature and salinity withoccasional desiccation. The T calfornicus used were collected from splashpools on a shelf rock, a large shale formation along the foot of the cliffs. .“As a short-lived organism (egg to C-V1 adult stage in approximately 21 days at20°C (see Chapter 4), T. calfornicus may be particularly susceptible to fluctuations in itsenvironment. Tigriopus ca4fornicus is often described as a generalist feeder (Vittor,1971; Dethier, 1980), tolerant to a wide range of salinity (normal activity observed from 0to 80%o) and temperatures (in excess of 30°C, including sIdden changes of 10°C ormore) (Huizinga, 1971; Kontogiannis, 1973). Hence, as an organism that couldostensibly live anywhere in the intertidal zone, it is particularly illustrative to ask why Tcalifornicus and the congeners and yariants of the genus do not.Tide pools, estuaries and other geographically-isolated coastal areas provide aproving ground for certain relationships between genetics and ecology “at a micro-geographical level” (Battaglia et al., 1978, p. 53), and with the provision of a fluidmedium may even surpass isolated terrestrial systems in this regard. Igarashi (1959)describes an inverse correlation of stable Tigriopus (I assumejaponicus) populations withfrequency of tidal inundation. Vittor (1971) finds a high degree of variability (andproposes plasticity) in the fitness traits of T cahfornicus populations continuouslyChapter 1: Habitat and Environmental Conditions 14exposed to the highly fluctuating temperatures and salinity of the supralittoral zone.Mechanisms for transport between exposed pools are limited, and accordingly, Burtonand Feldman (1981) and Brown (1991) find a significant constriction in gene flowbetween T. cahfornicus populations even those separated by only a few meters.While wave-washed shores can provide a formidable challenge to empiricalsampling, the exposed water deposits containing T caiqornicus are generally barren,small in size, and may be isolated from the sea for several days without evaporating orbeing replenished. This not only facilitates access to field sites, but provides naturalvessels in which to study changes in chemical and physical properties (e.g., Morris andTaylor, 1983) as well as short-term population response (Vittor, 1971; Dethier, 1980;Dybdahi, 1994).Agents of Dispersal for Splashpool CopepodsTigriopus species are nearly ubiquitous on temperate rocky shores, and arecommonly described as “restricted” to supralittoral splashpools from 2 to 5 m above meanwater level, depending on the degree of exposure. These ephemeral water deposits, oftenisolated from sea water replenishment for several days, may freeze in winter, evaporate insummer, flood from precipitation and runoff, and accumulate allochthonous shore debris.Given the ostensible similarity and widespread occurrence of Tigriopus congeners inbarren, short-lived water deposits, how then can the organism still be considered isolatedin these habitats?There exists a remarkable homozygosity within pools or TigrEopus californicusmetapopulations, yet Burton (1986, 1990) and Brown (1991) found populations ofT.calEfornicus to be genetically heterogenous between individual outcrops, ostensiblycontradicting the high capacity for dispersal commonly accredited to the organism (e.g.,Burton, 1986). On the basis of gene loci, Burton and Feldman (1981) found gene flowbetween inhabited outcrops to be significantly constricted. Burton and Swisher (1984)Chapter 1: Habitat and Environmental Conditions 15reported evidence of exchange of genetic material between pools within patches of T.caljfornicus habitation, while Brown (1991) found a high cost associated with individualpairings beyond the parameters of a single pool. Actively or passively, what means ofdispersal or recovery does it potentially utilize to maintain its position and sosuccessfully colonize temperate rocky shores?The term dispersal agent is used here in lieu of colonization vector; the formerterm emphasizing a means of transport away from the point of origin, but not assumingthe subsequent founding of a population by the organism so dispersed. Broadly, suchagents may be designated as: 1) abiotic agents, including wind, waves, and currentactivity; 2) short-distance biotic agents, providing dispersal over a limited area; and 3)long-distance biotic agents, providing widespread or even global dispersal over time.Acting in concert with any of these agents are the behavior of the organism, as well as itsphysiological tolerance and acclimation to sudden or gradual changes in habitat orclimate. The magnitude and influence of all these agents is additionally subject totemporal and seasonal variation.The current chapter proposes to detail the conditions extant in supralittoral poolscontaining T. californicus in Barkley Sound, British Columbia. Such a description isessential not only to appreciate the general conditions experienced by splashpoolorañisms, but lends credence to specific conclusions derived from either field orlaboratory study. In addition, it will present a non-experimental review and discussionof several ambient agents for dispersal, which may act to redisthbute T. californicusindividuals between isolated pools.Chapter 1: Habitat and Environmental Conditions 16MATERIALS AND METHODSA total of 394 splashpools over 10.4 km of shoreline or 312 000 m2 weresampled from coastal sites in Barkley Sound, British Columbia, Canada (field sitescentered at Lat. 500N; Long. 125°10’W, see Figure 1.1). From this initial census, 85pools were selected using stratified random sampling and monitored for the remainder ofthe study. Sampling intervals one to two weeks in duration corresponded approximatelyto changes in season: autumn (September, October), winter (December, January), spring(April, May), and summer (July, August), in the years 1994 and 1995. When conditionspermitted, additional pools found to contain T. californicus were also surveyed for bioticand abiotic features, providing the n values listed in Tables 1.2 and 1.3.Each pool was mapped according to:1. tidal elevation, determined relative to landmarks of known elevation, local tidetables (DFO, 1995; Canadian Coast Guard, Bamfield Detachment, pers. Comm.;N.J. Wilimovsky, pers comm.), and repeated measure from the waterline usingan inclinometer (sensu Kain, 1958);2. pool dimensions and volume, determined using a meter stick and 1 m2 quadrat;3. taxa and percent-cover of macroalgae (sensu Dethier, 1982);4. abundance of zoobenthos, using a 10 cm2 quadrat; and5. fundamental water conditions, including salinity, temperature, oxygenconcentration and hydrogen ion concentration. Salinity was recorded using aHanna Model 9033 conductivity meter; temperature using a Fisher field-protected thermometer; and pH using a Fisher Ailcacid full-range pH kit.Abundance of Tigriopus californicus (Baker) was also determined; data andanalyses of the density, age structure, growth and decay of T. ca4fornicus populationsare presented in Chapters 4 and 5.FIGURE 1.1. Area of study. Lined coastline indicates regions surveyed for Tigriopuscahfornicus pools; black coastline indicates the location of field sites monitored over thecourse of study.Chapter 1: Habitat and Environmental Conditions 17BarkleySoundCape BealeChapter 1: Habitat and Environmental Conditions 18RESULTSThe seasonal abundance, abiotic and biotic conditions of Tigriopus califomicuspools are summarized in Tables 1.2 and 1.3.Abiotic Conditions: From Table 1.2, the shoreline elevation of pools containingT. califomicus was remarkably similar over all seasons and field sites, differing only anaverage of ± 0.3 m and remaining above the highest average tide level (Figure 1.2).Within this restricted range, populations did not necessarily persist throughout the yearfor those pools that were monitored regularly (Chapter 5). Sediment in T. californicuspools was most prevalent in the spring, but coincided most closely with storm activityand adjacent sources of fine sediment. Both surface area and pool volume were highlyvariable, however in the absence of vegetation, the relatively large surface of the poolspossibly assists the diffusion of atmospheric oxygen to dense populations of T.ca4fornicus.Overall, 90.1% of all T. californicus pools were situated between 3.0 and 5.0 mtidal elevation. Although pooi surface area and volume were extremely variable, theratio of surface area-to-volume was consistently high (7.06 over all sites, seasons).From Table 1.2, mean pool temperatures consistently exceeded air temperatures andshowed less variation, in part from the cooling effects of wind and lithic retention ofsolar heat. Salinity ranged from nearly fresh water in autumn (diluted by precipitation)to l39% in at least one isolated summer pool; the annual mean was 30.2 ± 8%1. Therange of values observed precluded any calculations of statistical difference anddemonstrated a high degree of variation between pools. While irregularities in pH were1 Note: the accepted standard for providing salinity is Practical Salunity Units (PSU), which is presentedwithout units. Parts per thousand (%o) is used throughout this manuscript to facilitate comparison withprevious (biological) studies, and to remain consistent with the Instructions to Authors guidelines forthose portions of the thesis that are in press.TABLE12.Abioticconditionsof BarkleySoundsplashpools.Tabulatedvaluesareonlyfor thosepoolsfoundtocontainTigriopuscalfornicuspopulations.IMeanWaterPoolVolumeSurfaceAirWaterSalinityOxygenLevel(m)Elevation(m)(L)Area(m2)Temp.(°C)Temp.(°C)(°/)pH(mgfL)Autumn* mean2.** mean2. -6.7)(.1-55)(0.06-5.0)(-4- 10)(7- 14)(3.4 -32)(6.2-8.3)(3.5 -10.1)s.e.1.31.01712.***mean2. -6.7)(0-192)(0-50)(10-25)(17-33)(1.7- 139)(6.0 -9.1)(1.6-10.7)s.e.1.90.8676.*values from1994only;**=values from1995only;***values fromboth1994and1995.TABLE1.3.BioticconditionsofBarkleySoundsplashpoolscontainingTigriopuscalifornicuspopulations.-t I 1’.) CMacrollora(%-cover of)FaunaEnteromorphaScytosiphonEncrustingMixed%ofTigriopuspoolsspp.spp.spp.(var.)Sedimentcontaining:Individualsm2Autumn*Amphipods4mean5.,Balanusapp.)150range(5-5)n/a(5-30)(5-40)Crabs(Hetmgrapsisspp.)0.5s.c.n/an/a12.315.7Littormes(Littorinaspp.)90presentin2of880of8819of885of88Mites(Neomolgusandotherspp.)30(%)2.270.0021.605.68Sculpins(Oligocottusspp.)1Misc.-Anthopleura,Pisaster1Winter** mean16.812.55.50.0Littorines(Littorinaapp.)65range(5-30)(5-20)(5-10)n/aNematodes300s.e.10.310.61.9n/aSculpins(Oligocottusspp.)1presentin22of472of4710of470of47(%)46.814.2621.280.00Spring***Amphipods6mean20.920.226.325.0Barnacles(Chthamalus,Balanusspp.)112range(5-90)(5-70)(5-70)(10-80)Crabs(Hemigrapsisspp.)0.5s.c. -Acmaea,Pisaster1Summer***Arnphipods4mean19.60.05.617.0Barnacles(Chthamalus,Balanusapp.)80range(5-80)n/a(5-10)(5-40)Crabs(Henngrapsisspp.)1s.c.23.3n/a1.812.2Littonnes(Littorinaapp.)90present in23of 4980of 4988of49855of498Nematodes360(%)4.620.001.6111.04Ostracods15Misc.1.5*=valuesfrom1994only;**=valuesfrom1995only;***=valuesfromboth1994and1995.Chapter 1: Habitat and Environmental Conditions 21FIGuRE 1.2. Seasonal elevation of splashpools containing Tigriopus californicusrelative to mean water level. Water levels are averaged from local tide tables oversampling intervals in each season. HHW = higher high water; LLW = lower low waterfrom mixed, semi-diurnal tide conditions (DFO, 1995). Error bars on dotted linerepresent ± 1 standard error; lines on HWL and LLW average bars represent maximumand minimum levels over the study interval.5Figure 1.2. Seasonal Elevation of Tigriopus calfornicus PoolsRelative to Mean Water Level43I + — — — — t f — —— —___[_..C=C210Avg. l-IHWAvg. LLWMean Water Level•— Avg. Elevation ofTigilopas poolsAutumn—1WinterSeasonSummerChapter 1: Habitat and Environmental Conditions 22not noted in any particular area of the pools, temperature, salinity, and oxygen valueswere commonly higher at the bottom of pools than nearer the surface.Biotic Conditions: From Table 1.3, splashpools containing T. californicus weregenerally void of macroflora, with the highest co-occurrence of copepods and visiblevegetation occurring in winter (24.11% for all species). In summer, only 2.08% of thosepools containing T. californicus also supported these macroalgae. Overall algalabundance was lowest in the autumn, with the exception of encrusting species, includingRalfsia (common name: “tar spot”) or a Ralfsia-like alga. Cladophora trichotoma(“green ball”) and Enteromorpha compressa (“green confetti”) are present throughout theyear, but in autumn average 18.3 ± 6.82 and 5 ± 2.27%-coverage, respectively, for allpools surveyed. Prasiola meridionalis fringes some higher-elevation pools, especiallythose nitrified by guano.In winter, only Cladophora trichotoma was found regularly, occupying 30% ofthe available substratum, though not in those pools containing T. californicus (seeChapter 2). Enteromorpha compressa coverage averaged 16.8 ± 46.8%, Scytosiphonlomentaria averages 12.5 ± 4.26%-cover, hence its Ralfsia-like alternate phase is rarelyobserved at this time of year. Hild.enbrandia spp. are also found in some T. californicuspools, however determination of percent-cover and genera of encrusting algal mosaics,or sporadic tufts of species such as Endocladia, was found to be imprecise.In spring, the principal seaweeds were Enteromorpha compressa (20.9 ±11.46%) and Cladophora trichotoma (36.1 ± 3.65%), while Scytosiphon lomentariaand algal crusts reach their greatest annual abundance. During the highest seasonalabundance, phaeophytic algae and debris may color poois orange or red; Hildenbrandiaand Endocladia spp. often occur apart from other algae, and may become brownish incolor from epiphytic growths of nitzschioid diatoms. In areas of higher wave exposure,Ulva may also extend into the lower supralittoral zone but is not common in T.californicus pools.Chapter 1: Habitat and Environmental Conditions 23Scytosiphon lomentaria is entirely suppressed in summer, with the decayedmaterial sometimes leaving a yellowish sediment in T. californicus pools. The debris ofother macroalgae additionally becomes coated with diatoms and other periphyton(unidentified here, but see Fraser, 1936a; Taylor, 1993). Enteromorpha compressaoccurrence also diminishes slightly in percent cover, but much of this material formslarge mats of salt-encrusted filaments superficially devoid of chioroplasts. A secondspecies, E. intestinalis, occurs more commonly in summer than in spring. Cladophoratrichotoma persists as the most common macroalgae, averaging 28.8 ± 6.43%-cover inspring, but again, does not usually coincide with T. californicus habitation (see Chapter2).Dispersal Agents: Fauna common to T. californicus pools or the adjacentshoreline are summarized in Table 1.4. Salt water mites, gammaridean amphipods, andlittorines (Littorina sp.) are most common in the autumn and spring, with barnacles(Chthamalus and Balanus spp.), limpets (Acmaea sp.) and mussels (Mytilus spp.)extending into the lowest T. californicus pools. Crabs (Hemigrapsis nudus), starfish(Pisaster spp.), sculpins (Oligocottus maculosus and Clinocottus globiceps), andnernatodes (unidentified spp.) are also observed in T. californicus pools, most commonlyin spring, when vegetation is comparatively plentiful and physical conditions are lessextreme.The avifauna of Barkley Sound were considered as potential dispersal agents, butas an a priori consideration, could not be collected and examined for the presence ofectoparasites (including copepods) at the same time as the above data. As season andcapture restrictions reduced the number of birds potentially examined at the field site,avian specimens at the Smithsonian Museum of Natural History (Washington, D.C.)were instead inspected (species and specimen numbers listed in Appendix C). Avifaunacommon to the area include black oystercatchers (Haematopus bachmani), turnstonesChapter 1: Habitat and Environmental Conditions 24(Arenaria spp.), California gulls (Larus califomicus), and Glaucous-winged gulls CL.glaucescens) (Campbell et aL, 1990 and pers. obs.).Examination of all available specimens of bird species known to migrate over theBarkley Sound area, or rocky shores of a comparable latitude, did not reveal any T.calfornicus. However, other microcrustaceans (unidentified isopoda and copepoda) andisopods (unidentified spp.) were occasionally found in the plumage of museumspecimens of black oystercatcher (Haematopus bachmani) and California gull (Laruscalifornicus) (identification from specimen tags and Campbell et al., 1993).Sea lions (Eumetopias jubatus, Zalophus californianus) and otters (Enhydralutris) are common near at least one of the field sites (Wizard Islet), though at a muchlower elevation on the shore and not in the vicinity of the pools surveyed. Mink(Mustela vison) and deer (Odocoileus spp.) forage in the high intertidal zone. Leaf andseaweed debris, insect larvae and allochthonous shore materials are commonly found inthe highest T. californicus pools.Chapter 1: Habitat and Environmental Conditions 25TABLE 1.4. Incident fauna in Barkley Sound study sites. Species are listed as potentialdispersal agents for Tigriopus calfornicus.Incidental or Co-occurring Action of TransportMacrofauna (Genera) Classification Sessile Motile Short-Distance Long-DistanceInvertebrataAnemones(Anthopleura spp.) Anthozoa X N/AAmphipods(Traskorcheslia sp.) Crustacea X XBarnacles(Ba/anus, Chtharna!us spp.) Crustacea X N/ACrabs(Hemigrapsis nudus) Crustacea X XLittorines(Littorina sp.) Gastropoda X XLimpets(Acmaea sp.) Gastropoda X N/AStarfish(Pisaster sp.) Echinodermata X XVertebrataSculpins(Clinocottus, Oligocottus) Osteichthyes X XMarine Mammals(Eumetopiasjubatus,Zalophus californianus, Mammalia X X XEnhydra lutris)link(Mustela vison ) Mammalia X X XDeer(Odocoileus spp.) Mammalia X X XBlack oystercatchers(Haematopus bachmani) Ayes X XCalifornia gull(Laurus californicus) Ayes X XTurnstone(Arenariaspp.) Ayes X XRed Knot(Caidris canutus) Ayes X XSuribird(Aphrizia virgata) Ayes X X* Short-distance transport potential on islands.**Longer-distance transport potential on mainland,Chapter 1: Habitat and Environmental Conditions 26DiscussIoNThe following discussion provides a comparative discussion of 1) generalcharacters of splashpools in Barkley Sound, particularly those containing Tigriopuscalfornicus; and 2) the potentiality of several dispersal agents, which may serve toredistribute splashpool copepods between inhabited outcrops. This latter considerationwas not tested experimentally for the current thesis, but is included in discussion since athorough consideration of potential dispersal agents and their mechanism for transport isclearly fundamental to the understanding of the copepod’s observed distribution.Habitat CharactersAbiotic Habitat Characters: The supralittoral habitat of Tigriopus californicuscan be likened to an “intermittent estuary,” experiencing as it does the saline influence ofwave splash, followed by periods of evaporation or fresh water influx from precipitationand runoff. Steep relief with an accompanying cliff face is a common aspect ofshorelines where T. calfornicus pools are found. The bedrock may be granite,limestone, or shale, but a common feature is the protrusion of shelf rocks or ‘benches’,forming a raised platform angling sharply into the sea (cf. Lear and Oppenheimer, 1962;Harris, 1973). Flattened foreshores, which flood gradually with the incoming tide andimmerse pools by several centimeters appear to be less effective at retaining T.californicus populations, perhaps due to the retention of more potential predators or themagnitude of hydrodynamic effects acting on microcrustaceans swimming above thebottom. Steep shorelines that produce wave splash may also assist the replenishment orre-distribution of supralittoral copepod populations on a single outcrop (see below).Fraser (1936a) sampled pools ranging in shoreline elevation from -1.33 feet to12.73 feet (-0.4 m to 3.88 m), the higher extreme occurring 1.5 m above the high-watermark and the only level observed to contain T. fulvus (at populations of over 800individuals . L1). Dethier (1980) found pools above 2.2 m elevation to contain TChapter 1: Habitat and Environmental Conditions 27caljfornicus, with a sharp decline in pools occupied by copepods below that level.While the elevation of T. californicus will depend on the degree of shoreline exposureand absolute tidal range, Figure 1.2 illustrates that in Barkley Sound, T. californicuspools remain isolated from average tidal flux, and are probably only inundated by thesea on a few days in each tidal cycle. Dybdahl (1994) made a similar observation,relating this to the ephemeral nature of splashpools, particularly those with a highsurface area.Published accounts frequently omit details of water quality and habitatconditions, even though these features directly influence the organisms within the studyregion (Morris and Taylor, 1983; Metaxas and Scheibling, 1993). The typical size of pooibasins (4.57 ± 1.65 m2 surface area; 62.25 ± 22.13 L volume) agrees with the range ofvalues recorded by Fraser (1936a) and Dethier (1980), however shoreline topography andhigh levels of precipitation may “bleed” several small, neighboring pools into one another,and greatly extends the upper range of these parameters. The surveyed pools reflect this,with the greatest poois sizes occurring at the time of highest precipitation in the area (11.5mm day1 in autumn and 11.9mm . day1 in winter, see Appendix B). Harris (1973)described pools of 20 L volume and 30 cm depth during spring sampling of T.brevicornis; Dethier (1980, p. 102) observed T. californicus pools to be “usually less than10 L.” Fraser (1936a) recorded pooi volumes of 7.5 to 84 L. The values in Table 1.2range from less than 5 L to over 110 L for some diluted spring pools. Atmosphericconditions, shoreline exposure, and bedrock contours will obviously produce a highdegree of variability in this parameter; for the current study, no season produced T.ca4fornicus pools of significantly different surface area or volume.The values in Table 1.2 for temperature, salinity, pH, and oxygen lie within thewide range of values for these parameters published by Morris and Taylor (1983) at acomparable latitude. Harris (1973) recorded a salinity range of 30.2 to 35.2% and atemperature range of 8 to 23°C for pools containing T. brevicornis. Egloff (1966)Chapter 1: Habitat and Environmental Conditions 28reported air temperatures of 9 to 29°C over an 18-month interval to approximate therange of water temperatures, and all published accounts for in situ ranges fortemperature and salinity (including Table 1.2) fall well within the tolerance recorded forT. californicus in laboratory culture (Huizinga, 1971; Kontogiannis, 1973). Unpublishedpersonal observations of other T. californicus pools elsewhere in British Columbia,Washington, Oregon, and California have yielded similar results over the describedgeographic range of this species, and coincide with descriptions of other temperate areas(e.g., Gustavsson, 1972, in Sweden; Fraser, 1936; Clark, 1968; Harris, 1973; and Morrisand Taylor, 1983, in the United Kingdom).Biotic Habitat Characters: In Barkley Sound, the water of splashpools mayacquire any number of remarkable colors, including green (from Tetraselmis blooms),orange (from leached phaeophytes or even from the density of resident Tigriopuspopulations), red or yellow (from the tannins in logs or leachates from red or brownalgae), white (from bacteria or sulfur production), pink (from Oxyrrhis dinophytes) orcolorless and transparent (F.J.R. Taylor, pers. comm.). While the occurrence of bacteriaand unicellular algae is virtually assured in these pools, identification of the speciespresent is not easy. Further, the culturing process used to identify bacteria speciesdistances this identification from any reliable description of in situ conditions. Takano(1971) mentions the 20- to 35-pm long dinophyte Oxyrrhis marina Dujardin asoccurring naturally in the habitat of T. japonicus, but Takano (1968, cited in Takano,1971, p. 72) found that Oxyrrhis “competed against the larvae of the copepod by feedingupon the same food.” Reliable accounts of the natural abundance and identity ofmicrobes in Tigriopus pools are unavailable, however those species noted to occur in thehigh intertidal zone express a high degree of seasonality in their occurrence.Both Tetraselmis and Oxyrrhis are most abundant in the summer months, andalthough both may bloom, they do not typically co-occur with each other (F. J. R.Taylor, pers. comm.) Decay and putrefaction of algal debris, and the bacterial activityChapter 1: Habitat and Environmental Conditions 29promoting this process, have previously been related to Tigriopus occurrence (e.g.,Fraser, 1936a). Alternately, microflora may assist in the nutrition of T. californicus byfacilitating the uptake of nutrients across the copepod’s exoskeleton (see Anderson andStephens, 1969; Khalov and Yerokhin, 1971; Carli et al., 1993). Anthropogenic inputsor nitrogen introduction from animal excreta does not appear to enhance T. californicuspopulation growth.With few exceptions (e.g., Fraser, 1936a) co-incident supralittoral macroalgaeare not described in the literature on Tigriopus species, although Dethier (1980)mentioned algal crusts and opportunistic Enteromorpha, a filamentous green macroalgaenoted for its ability to grow in the absence of water flow. Filamentous Enteromorphaand Scytosiphon likely utilize the ample supply of freshwater from precipitation andrainfall; the ancillaiy pigmentation of the phaeophytes may also take advantage of theweaker springtime sunlight. The results of macroflora percent-cover from Table 1.3concur with those of Fraser (1936b), Gustavsson (1972) , Morris and Taylor (1983) andDethier (1980) for temperate, supralittoral splashpools.Among co-occurring fauna, Fraser (1936a) included Littorina rudis, ostracods(Cythene lutea), Daclylopusia brevicornis (Claus), D. vulgaris Sars, Idyafurcata(Baird), Amphiascus minutus (Claus), the harpacticoid Amphiascus minutus, andChironomous larvae in his field samples of T. fulvus. Dethier (1980) noted littorines, aswell as dipteran larvae, grapsid and pagurid crabs in T. calfomicus pools. At thehighest shore elevations, Fraser (1936a) found splashpool plankton to be up to 99.98%monospecific (T. jldvus), in contrast to the highest species diversity, which was found atthe mid-littoral level. From the current observations, T. caljfornicus pools are largelymonospecific, with other species rarely exceeding a few individuals per sample.Incidence of these other species (not identified) also appear to relate to season and therelief of the beach face: spring plankton populations are typically more diverse, whilelow-relief shores are more likely to contain non-Tigriopus specimens. Insects, leafChapter 1: Habitat and Environmental Conditions 30debris, and incidental vertebrates are all factors reasonably influencing splashpools ofthe exposed supralittoral zone.Dethier (1980) discussed predation as an influence restricting the lower intertidaldistribution of T. californicus. In her study, Tigriopus poois introduced with anemones(Anthopleura) or cottids (Oligocottus) showed marked reduction in population numbers,however the predators themselves were similarly distressed by the physical conditions ofthe pool. The orange coloration and jerky’ swimming motion of Tigriopus may alsomake them attractive to visually-oriented prey (J. M. Ganning, 1971). Dethier’s (1980)study also demonstrated that T. calfornicus can survive in pools lower in the intertidalzone, provided that predators and wave scour are removed. Mussels have been observedto eat copepod larvae, but not adults (K. G. Kopley, pers. comm., cited in Dethier,1980), and I suggest the same potential in barnacles (Chthamalus and Balanus spp.).The number of naturally-occurring aquatic predators in supralittoral pools isscant. Gammaridean amphipods are found in T. californicus pools, but have not beenobserved to feed on Tigriopus, nor are they found in sufficient numbers (typically 4 to 6individuals . L1) to provide significant culling of T. californicus. The size of the poolmay be too small for most free-swimming predators, and the physical conditions toosevere for sessile predators. The most significant agents responsible for cullingestablished Tigriopus populations may then be predominately cannibalism, desiccationand wave-wash (but see below, and chapters 2 and 3).Burton and Feldman (1981) suggested that, while complete extinction ofTigriopus populations is unlikely, regular depletion of populations may occur, either dueto wave activity or seasonal changes in climate and water properties. Dybdahi (1994)considered T. calfornicus pools on the same rock outcrop as forming a metapopulation:a collection of local populations experiencing periodic extinction and re-colonization,which is especially characteristic of subdivided or fragmented habitats. He furtherreported extinction of T. califomicus populations in 35% of his study pools over a periodChapter 1: Habitat and Environmental Conditions 31of six to eight weeks. On occasion, I have discovered pools in which T. californicuswhich were nearly all apparently deceased. Temperature and salinity were notanomalous in these pools (within the limited time frame of the measurements taken),however this does not preclude the possibility of thermal or haline shock from a rapidchange in these parameters, or the presence of a localized, unidentified pollutant. Thesepools may also have been evaporated pools recently hydrated by runoff or wave splash(Chapter 3).Egloff (1966) suggested that summer populations of Tigriopus ca4fornicus areinfluenced less by storm activity and wave splash. While wave conditions may be lessextreme in the summer, I suggest the influence of evaporation and stagnation maybecome much more pronounced, particularly in wanner climates. Further, evenpopulations which are trapped in evaporated pools do not necessarily become ‘extinct,’as there exists the potential for individuals to resume normal activity following rehydration (Chapter 3). Hence, in comparing the conditions of Tigriopus-inhabited pools,parity of season and latitude between study sites are essential considerations.Dispersal AgentsInformal observations of Tigriopus califomicus pools in other areas of BritishColumbia, Washington, Oregon, and California have indicated similar conditions overmuch of the described geographic range of this species. While favoring T. californicus,the following discussion may be applied to all Tigriopus habitats at a comparablelatitude.Abiotic AgentsHydrochory: The action of waves and currents on exposed, rocky shores must beconsidered as a principal mechanism for re-distributing T. californicus. Igarashi (1959)found a correlation between Tigriopus (I assume japonicus) population stability and theintertidal elevation of inhabited pools. In his study, no Tigriopus were found in poolsChapter 1: Habitat and Environmental Conditions 32routinely flooded at high tide; older populations of varying density were found in high,isolated pools, and younger, less dense populations described at intermediate levels.For those pools inundated least frequently by tide or wave activity, Tigriopuspopulations may be more significantly influenced by precipitation and drought (Igarashi,1959). The position of the pools in the current study (1.9 ± 0.3 m above the averagewater level and 0.8 ± 0.1 m above higher high water levels) suggests that wave splashmay act significantly in the replenishment of T. californicus metapopulations, andsupports the findings of Burton and Swisher (1984), that at least some transfer ofindividuals may occur between adjacent poois. Runoff, particularly from heavy rainfall,may wash copepods downslope into larger poois, however, although I have found T.californicus in shallow crevices or on moistened surfaces between pools, it is not typicalfor the lower of ‘stepped’ pools to collect T. californicus washed from poois of a higherelevation.Regular inshore transport by flood tides should also be considered a significantinfluence (Igarashi, 1959; Vittor, 1971), but primarily for those pools located at a lowertidal elevation and therefore more frequently flushed. R. Burnett (pers. Comm. cited inMorris et al., 1980) finds pool populations of vital-stained T. californicus to undergo anexchange of nearly half their numbers after a few days, although the net abundance ofindividuals in the pools changes very little. This suggests not only a potential ‘carryingcapacity’ for pools, probably based on food abundance, but also: 1) T. californicusprobably do not or cannot relocate to their ‘home’ pools following wash-out by wavesplash; and 2) ‘source’ populations of T. califomicus comprised of displaced individualsmay well exist immediately offshore from outcrops or headlands, but these do notdisperse or survive in the water column long enough to colonize adjacent shores. As anexotic or unfamiliar species to either offshore or soft-bottom plankton communities, the‘absence’ of 7’. californicus from such samples may often be a case of overlooked orChapter 1: Habitat and Environmental Conditions 33misidentified specimens. However, if indeed present in these locations, Tigriopuscopepods clearly do not bloom there to the extent they do in splashpools.Given the broad geographic range of T. californicus (Baja, California, to 58°20’N, sensu Belser, 1959; Dethier, 1980), longshore transport should also be considered as apotential dispersal agent, and the major surface currents of the NE Pacific Ocean areillustrated in Figure 1.3. Northward offshore transport by the Alaska Current, southwardtransport by the California Current, or the opposing inshore circulation of the DavidsonCurrent are immediately apparent mechanisms for the transport of T. califomicus alongthe Pacific shore of North America. However, were longshore transport a substantivemeans of dispersal between colonized areas, T. californicus should be commonlydeposited in sedimented coastal areas, as well as in plankton hauls or benthic samplesfrom stations adjacent to or located between inhabited rocky shores.Although it is a common occurrence for T. californicus individuals or even entirepopulations to be displaced from supralittoral pools by wave splash or a flood ofprecipitation, it is likely that the fate of most of these copepods is to be washed backonto the shore by the subsequent onshore wave action, or to be culled by visually-oriented predators in the open sea. Additionally, T. calfomicus is not a particularlystrong swimmer, even in motionless aquaria. The copepod appears to fatigue quickly inits swimming (casual observations of cultures in 25 L vessels), and prefers to occupy thebottom of the vessel. Under low-energy or stagnant conditions, the argument might bemade that, whether from fatigue or active downward swimming, the organism wouldsettle into the lower portion of the extant water column, could be carried downshore andultimately transported along the shore by deep water currents. But again, if the copepodis transported along the shore between locales by waves, surface or bottom currents, thisdoes not account for the organism’s absence from sedimented areas between rockyoutcrops. Vittor (1971) reported finding no T. californicus in plankton haulsimmediately offshore of inhabited outcrops, nor have I had success in identifying theChapter 1: Habitat and Environmental Conditions 34organism in net hauls from offshore the field sites in Barkley Sound. This does notsuggest the organism is not found in coastal ocean currents, but only that its presence isas-yet undetectable. In addition, dipnet or SCOR net sampling along high-energy rockyshores does not produce satisfactory results2 (see General Discussion).Wind: Microcrustacea from estuarine areas, lakes or salt water pools maypersist in evaporated basins as encysted eggs, to be passively dispersed by wind (Brownand Gibson, 1983), and T. californicus may be similarly re-hydrated from virtually alllife stages, including the gravid female (Chapter 3). This observation not only allowsthe copepod to endure transport, as by wind or avifauna, but also retains the ability ofthe copepod to produce a viable population almost immediately once delivered to asuitable habitat, and without requiring a mate for insemination once there. it is notuncommon, particularly in summer, for T. califomicus pools to evaporate completely,exposing the copepods in the bottom of their pool at a density of several thousandindividuals per liter (Chapter 3). By extension, it is possible that desiccated T.ca4fornicus waifs are dispersed by wind, and potentially carried to a hospitable pool or aregion of the shore receiving more immediate moisture replenishment (within 5-7 days,from Chapter 3).Short-Distance Biotic AgentsSupralittoral Fauna: Invertebrate macrofauna in supralittoral pools is oftensparse, particularly in the summer, when desiccation and evaporation within this zone isintense. In lower pools, mussels may filter T. californicus nauplii from suspension (K.G. Kopley, pers. comm., cited in Dethier, 1980, p. 102). The same might be assumedfor larger barnacles (Balanus spp.), but has not been demonstrated in situ. The motilityof littorines and amphipods provides a (slightly) more motile means of transport, but2 Alternate means of sampling microcrustacea from such areas, including the use of mounted planktontraps, was not possible during the time available for sampling.Chapter 1: Habitat and Environmental Conditions 35FIGURE 1.3. Current patterns of the NE Pacific Ocean. Generated by wind, thedivergence of the North Pacific Current as it reaches the coast of North America movesslightly northward, from 45°N Latitude in winter to 50°N Latitude in summer (Pickardand Emery, 1982). The Shelf-Break Current reverses direction according to theprevailing seasonal winds, and follows the 200 m isobath (approximately indicated bydotted line). In winter, the Vancouver Island Coastal Current (VICC) is driven by theprevailing winds as a northward extension of the Davidson Current; in spring, thetransition in wind direction generates the cyclonic Juan de Fuca Eddy. Square onthumbnail map indicates area enlarged; square on enlarged map indicates study area.Illustration derived from Thomson (1981) and Thomson et al. (1989).Chapter 1: Habitat and Environmental Conditions 36these would presumably still be restricted to a very small area of the shore, perhaps evento a single pooi.Egloff (1966) proposed grapsid and pagurid crabs as potential carriers of T.ca1fornicus between pools in California. From a limited data set (n = 5 Pachygrapsuscrassipes), all life-history stages and as many as 73 individuals were found on a single P.crassipes carapace, though the density of the source T. calfomicus population is notprovided. Egloffs (1966) suggestion is commonly reiterated in the literature (as byDethier, 1980; Burton and Feldman, 1981; Dybdahl, 1994), without any conclusiveevidence in support of this mechanism. From the calculations of Vittor (1971) andDybdahi (1994), the transport of a small number (eight to 10) of a variety of life-historystages could potentially re-populate a pooi. In the Barkley Sound pools, Hemigrapsisnudus is the only crab found consistently in T. californicus pools; I know of nopublished “home range” for the species, however hitchhiking on larger crustacea isdoubtfully as effective as wave surge for mass redistribution of copepods withinmetapopulations. The viability of copepod redistribution on crabs or starfish mayadditionally be lessened by: 1) the carrier moving lower on the shoreline (into pools ofhigher exposure to waves, or higher abundance of predators); or 2) the increasedpotential for predation by visually-oriented predators, including birds, by associatingwith a larger, more conspicuous invertebrate.Dethier (1980) proposed predation by cottids and anemones as a major influence‘restricting’ T. californicus occurrence lower in the intertidal zone. Ganning (J. M.,1971) suggested the orange coloration and erratic swimming style of the organismmakes it particularly susceptible to visually-oriented predators, and Burton and Feldman(1981) concur that predation as well as organism behavior may reduce the number ofindividuals transgressing established metapopulations. Although the influence ofpredators is curtailed in situ by the extreme physical conditions in supralittoral pools, Ihave observed anemones as well as sculpins in some T. californicus pools. From GreenChapter]: Habitat and Environmental Conditions 37(1971), Oligocottus and other sculpins in the high intertidal possess home ranges,enhancing the likelihood of localized T. californicus exchange by sculpins or otherinshOre fishes, but not to an appreciable extent downslope or along the shore.Mink and deer are also commonly observed to traverse the Barkley Sound fieldsites, and may incidentally collect T. californicus on their appendages or pelts. Ottersand sea lions are not observed at the same tidal elevation as most T. californicus pools inthis study, but might be considered as incidental vertebrates in other field sites.Additionally, while incidental vertebrates may disturb quiescent pools in passing,eutrophication or nitrification from animal excreta does not appear to enhance T.californicus population growth (cf Ganning and Wulff, 1969). In more populated areas,domestic pets might similarly act as carriers of individuals; in Barkley Sound, the brokenshoreline and isolation of these particular field sites reduces the influence of humans ordomestic pets, but the general ease of shoreline-access to splashpools does not precludethis kind of disturbance in other areas. The viability and effective distance of dispersalby these terrestrial agents would seem to be limited by: 1) resthction of dispersal routesfor land mammals on island sites; and 2) the movement of these animals inland andthrough forests to a much greater extent than along exposed rocky shores. As mentionedabove,Long-Distance Biotic AgentsAvian Carriers: As anticipated, the handling and preparation of the birdspecimens precluded reliable determination of the number of individuals, and which life-history stages, might potentially have been carriedhy the birds. Although the museumspecimens I have examined to date have carried no T. californicus in their plumage,species endemic to the study area (from Campbell et al., 1990) have been observed toretain other microcrustacea, including copepods and isopods. Harpacticoid copepodsChapter 1: Habitat and Environmental Conditions 38typically represent the second-most abundant fauna in meiobenthic communities3,andas such are probably good candidates for incidental collection in the plumage or on theappendages of foraging birds. For other Crustacea, Schmitt (1967, p.100) providesanecdotal accounts of gulls and penguins foraging selectively for amphipods. Moreover,the coastal area extending through Barkley Sound from Baja, California, to the Arctic isa major migratory corridor for dozens of bird species endemic to the Barkley Soundarea, with some of these (e.g., red knot, Calidrus canutus) extending their range towestern Europe (Campbell et al., 1990) or the Atlantic coast of North America (where T.calfornicus has not been described).Assuming a 10 - 15% recovery of desiccated individuals and a founding copepodpopulation of eight to 10 individuals (see Chapter 3), only 100 to 150 T. californicusretained by a bird (or birds) foraging in the supralittoral zone would be sufficient toprovide dispersal in this manner. At the in situ population densities T. californicus mayattain (often in excess of 20 individuals L’, with a mean in excess of 750 individualsL4 over much of the year, Chapter 5), such estimates are not unreasonable and providean avenue worth further examination. Clearly, examination of a larger number of birdspecimens, captured by happenstance or with a banding permit in the vicinity of the fieldsites, is required to evaluate more accurately the potential of birds as dispersal agents ofT. californicus.Rafting: Transport of copepods on driftwood or broken macroalgae alsoprovides a plausible mechanism for dispersal (P. K. Dayton, pers. comm.). T.californicus pools often contain wave-swept debris, and were this material “colonized”by copepods, its subsequent redistribution might carry some individuals along the shore.Given the high elevation of most of the pools in Barkley Sound, the provision andrelocation of raft material would be accompanied by intense wave action, and it wouldSecond only to nernatodes in terms of absolute abundance (Hicks and Coull, 1983).Chapter 1: Habitat and Environmental Conditions 39be difficult — if not impossible— to determine the proportion of copepods transported byrafts, relative to those carried by the waves themselves.CONCLUSIONSSplashpool colonization by T. califomicus appears to occur irrespective ofvegetation by macroflora, suggesting that in situ the copepod is most likely abacteriovore or rasps a mixed diet of available food resources off the substratum. Theextreme flux in physical conditions experienced in supralittoral pools may create anephemeral habitat for T. caljfornicus, but one which restricts the presence of potentialpredators or competitors over much of the year. Analyses and discussion of T.californicus population response to the conditions within this extremely stressful habitatwill be the subject of the following chapters.Redistribution by wave splash may partially explain the position of T.caljfornicus pools relative to average water levels, but the heterogeneity of adjacentmetapopulations and the conspicuous absence of the copepod on sandy beaches or inoffshore areas does not support longshore transport as an agent of dispersal. Responsesof T. calfomicus to chemical secretions or sudden disturbances within this refuge arelikely more effective at retaining position than assisting dispersal, but probably functionprimarily under tranquil conditions.Transport by other invertebrates or incidental mammals may occur over shortdistances, but may also make the copepod more susceptible to predation via itsassociation with a larger organism. Land mammals may redistribute copepods amongsupralittoral water deposits, but this does not explain the degree of island colonizationobserved. Maritime birds may therefore be the only effective dispersal agents over anyappreciable distance.CHAPTER 2: THE RESPONSE OF TIGRIOPus CALIFORNICUS TO CHLOROPHYTICMACROALGAE, INCLUDING CLADOPHORA TR1CHOTOMA KUTzINGINTRODUCTION“There is no banquet but some dislike something in it.”— THOMAS FULLER (1732)Tide pool classification, algal surveys, community dynamics and succession in thelittoral zone have been addressed by a legion of studies, including Fraser (1936a); Kain(1958); Gustavsson (1972); Dethier (1982) and those reviewed in Metaxas and Scheibling(1993). Among these, the supralittoral zone provides a unique intermediary betweenintertidal habitats and emergent substrata. Pools located above mean high water (MEW)may be more directly influenced by atmospheric conditions than tidal action (Igarashi,1959; Egloff, 1966; Vittor, 1971; Morris and Taylor, 1983), and commonly experienceextreme fluctuations in various water properties, including: temperature (due to sunlightabsorption and lithic heat retention), salinity (due to runoff, precipitation, freezing orevaporation), oxygen and pH (due to biological activity).Common to the fringes of temperate supralittoral pools is the alga Cladophoratrichotoma (C. Agardh) Kutzing (common name = “green ball”). Befitting its name, C.trichotoma grows in hemispherical, bright green tufts 3 to 6 cm in diameter and iscomposed of short, branched filaments up to 1.0 mm in length and 0.2 mm in diameter(Scagel, 1957; Waaland, 1977). Representatives of this complex and ill-defined genus arefound on sand and mud flats (Guberlet, 1956) as well as high on exposed rocky shoresand reefs (Waaland, 1977) from British Columbia to Mexico. The opportunisticchiorophyte grows very rapidly in thick, turf-like mats - to the extent that it potentially40Chapter 2: Response to Macroalgae 41competes with sessile invertebrates for attachment space - until it is sloughed off by waveaction.Equally common to the exposed, rocky Pacific coastlines ofNorth America is theharpacticoid copepod Tigriopus caiqornicus (Baker). The species has been described inhigh elevation supralittoral splashpools from Alaska to Baja, California (Monk, 1941;Belser, 1959; Dethier, 1980) and similar habitats have been reported for its congeners,including T. brevicornis (Harris, 1973, in the U.K.), T fulvus (Battaglia et al., 1978, inItaly), and T japonicus (Takano, 1971, in Japan). Faced with the characteristics of itsephemeral and often barren supralittoral habitat, it is not surprising that the genusdemonstrates a remarkable tolerance to physical conditions, including sudden or extremechanges in temperature and salinity (Ranade, 1957; Huizinga, 1971; Kontogiannis, 1973).Over nearly two years, seasonal changes in supralittoral macroalgal compositionand Tigriopus calfornicus distribution and abundance were monitored in Barkley Sound,British Columbia. Throughout the year, T. calfornicus populations are commonly foundin pools containing algal crusts, green algae such as Enteromorpha compressa (Linnaeus)Greville and E. intestinalis (Linnaeus) Link, as well as in poois lacking any uprightvegetation. However, pools containing Cladophora trichotoma are not observed toretain populations of T calfornicus. During preliminary studies, even C. trichotomapools inoculated with T calfornicus cultures showed no evidence of copepod habitationafter only a few days. Among the agents potentially responsible for this apparentexclusion are: 1) more direct exposure to wave action (Igarashi, 1959); 2) atmosphericconditions and water properties (Vittor, 1971; Morris and Taylor, 1983); 3) nutrientsupply; 4) co-incident fauna (Dethier, 1980); and 5) macromolar compounds such aschemical attractants or anti-feedants (Bozic, 1975; Shaw, 1994).Tigriopus species have been experimentally associated with chemically-mediatedbehavior for at least two decades, albeit mainly from behavioral inference and without theidentification or isolation of the agent(s) involved. Bozic (1975) proposed anChapter 2: Response to Macroalgae 42‘aggregation pheromone’ response in Tigriopus (I assume fulvus) to vessels whichpreviously held copepod cultures. Studies by Kahan et al. (1988), Lazzaretto et al.(1990), Kahan (1992), and La.zzaretto and Salvato (1992) also described density-dependent chemical messengers which may variously regulate maternal and cannibalisticbehaviors in T. calfornicus, T. fulvus and T japonicus. Yet, while chemically-mediatedbehavior or population response to noxious substances can be readily observed, theisolation and identification of these chemical exudates is a formidable undertaking evenunder laboratory conditions. The elucidation of recognition factors and their potential toelicit response(s) is more difficult still. Recognition factors doubtless play instrumentalbut differing roles in free-flowing, intermittently-mixed, or isolated aquatic systems. Anyof these conditions may exist in temporary rock pools or supralittoral splashpools,complicating both the activity and detection of chemical agents. In a small, isolated waterdeposit, one can speculate only that the combined influence of an organism’s ownsecretions, the chemical attractants and anti-feedants released by its food resources andthe compounds released from prospective predators must create a tantalizing (ifconfusing) aromatic cocktail.The current chapter provides data examining the validity and extent of theapparent exclusion of Tigriopus cahfornicus from pools containing Cladophoratrichotoma. In doing so, the possible influence of chemical exudates may be revealed byregulating or isolating more obvious parameters affecting splashpool communities,including the relative degree of wave splash, pool volume, temperature, salinity, andsubstrate type. For the current chapter, the alga Enteromorpha compressa and itsconspecific E. intestinalis will provide phycological comparison with anotherchiorophyte. Although the phaeophyte Scytosiphon lomentaria is also commonly foundin winter pools containing T ca1fornicus (Chapter 1), and possesses long, grass-likefilaments akin to Enteromorpha, during the summer S. lomentaria occurs in its alternatephase, the encrusting Ralfsia pacifica. This marked difference in algal morphologyChapter 2: Response to Macroalgae 43between seasons was the predominate reason for not also including a similar comparisonof “substrate type” between C. trichotoma and S. lomentaria.MATERIALS AND METHODSField sites: Splashpools on Wizard Islet (Lat. 48°52’N: Long. 125°1O’W) andHelby Island (48°51’N: 125°1O.5tW)in southeastern Barkley Sound were surveyed duringintervals in January, May, and August, 1995 (see Figure 1.1). Each pooi was mappedaccording to the methods described in Chapter 1, while copepods were sampled bydividing the surface of each pooi into a numerically-assigned sextet, then rolling a die toselect the position of three random samples taken by a 30 mL graduated pipette drawnalong the substratum (also detailed in Chapter 1).On each island, all pools selected for study were located within 100 m of eachother, and were sampled within hours on the same day, hence atmospheric conditionswere assumed constant for each sampling day. While not measured directly, the possibleeffects of exposure to wind or wave action were isolated by assigning treatments withineach area by stratified random sampling according to shoreline elevation (greater than 3.0m = “high elevation”; less than 3.0 m = “low elevation”) and orientation according toleeward (= “low exposure”) or windward (= “high exposure”) position on a givenoutcrop. Pools were additionally classified as having either: 1) no visible vegetation; 2)growth of Enteromorpha compressa or a combination of E. compressa + E. intestinalisto the extent of at least 30% cOver; or 3) growth of Cladophora trichotoma to the extentof at least 30% cover. The 30% level was arbitrarily chosen as an amount of algal growththat could significantly affect: 1) the degree of protection afforded T. californicus againstdesiccation, wave splash, or predation; 2) water conditions in situ, includingoxygenation, pH, and dissolved organic material; and 3) the amount or concentration ofexudates potentially produced.Chapter 2: Response to Macroalgae 44Field Measurements: Splashpool pH was recorded using a Fisher Alkacid full-range pH kit; salinity using a Hanna Model 9033 multi-range conductivity meter; oxygenusing a YSI Model 57 oxygen meter (calibrated for salinity from 0 to 40%o’); andtemperature using a Fisher field-protected thermometer. Temperatures were recorded ateach 5 cm depth (when permitted by pool depth) to determine the degree of thermalsiratification.Differences in Cladophora, Enteromorpha, and non-vegetated pool parametersincluding surface area., volume, temperature, salinity, percent-cover of macroalgae, andfaunal abundance were evaluated using a single-factor Kruskal-Wallis analysis of varianceby ranks or Mann-Whitney test at a = 0.05 (Zar, 1984). For those pools containingT. californicus, samples were collected in triplicate on each day of the sampling interval(5 days) and returned to the laboratory for identification and enumeration. Pools lackingT. californicus were inoculated with approximately equal numbers of individuals (100-300 individuals L’ pool volume, transferred from inhabited pools) and sampled eachday over the same interval. None of the treatment pools was stringently scoured of allcopepods prior to inoculation (sensu Coull and Wells, 1983), and it is possible that somepools surveyed and determined to ‘lack copepods’ may have contained small residentpopulations which were later sampled. Scouring, pumping, or other means of treatmentpreparation were avoided as this may have produced undesirable side effects, particularlywith regard to any chemical exudates in the resident pool water.Laboratory Cultures: Samples of E. compressa and C. trichotoma for laboratoryuse were collected from each site and maintained in a flow-through sea water table at Ca.15°C, 5 to 8 mg. oxygen and 30 to 35% salinity. Tigriopus californicus werecollected and retained in 2 L Erlenmeyer flasks at room temperature. From thesecultures, egg sacs were removed from gravid females and allowed to hatch, providing aculture of nauplii for use in microcosms. To correct for acclimation effects (i.e., previousOxygen data was therefore not recorded for pools with salinity greater than 4O%,Chapter 2: Response to Macroalgae 45exposure to bacteria, macroalgae, chemical agents), copepod cultures from au pool typeswere combined, then gradually converted to prepared seawater sensu Morel at al. (1979)over three to four days.Laboratory Microcosms: In order to better control external influences andprovide greater resolution of T. californicus response to the presence of E. compressaand C. trichotoma in stagnant solution, the following microcosms were prepared: Plastic1 L Nalgene bottles were cut width-wise into 500 mL ‘bowls’ that were then filled withCa. 400 mL of unfiltered sea water and Ca. 15 g (wet weight) of either E. compressa +intestinalis or C. trichotoma. The algae were rinsed in sea water and wiped dry usingpaper towels, but no other attempt was made to remove any organisms living on oramong the algal filaments. A total of 18 microcosms (6 x each treatment type) wereprepared for immature copepods (eggs and hatched nauplii- stages N-I to N-VI), and asecond set of 18 treatments for juvenile (copepodite stages C-I to C-ffl) and adult (stagesC-1V to C-VI) using the cultures described above. The microcosms were retained atroom temperature and observed for five days or until the copepods showed no furtherdecline in numbers (death or apparent death of individuals).RESULTSPool Conditions: Although isolated splashpools were observed to experiencesubstantial changes in surface area or volumetric flux due to evaporation or precipitation,different types of pools (i.e., pools without macroalgae, those containing C. trichotoma,or those containing E. compressa, Table 2.1) did not differ statistically in pool dimensionsor changes in water volume (Kruskal-WallaceH005,60.05 <P < 0.1) for any of thetreatment types. While surface area and pool volume each exhibited a tremendous rangeof values within treatment type, the decline in T. califorhicus numbers was similar, asindicated by the mean ± 1 standard error values, even between pools of high and lowexposure to direct wave action. Weather was unseasonably warm, dry, and stable duringChapter 2: Response to Macroalgae 46the spring (May, 1994) interval, surpassing even the August climatic conditions foratmospheric temperature, hours of sunlight and overall rate of pool evaporation.Measured pH was not statistically different between Enteromorpha, Cladophora,or non-vegetated pools at any time, and usually varied between 6.0 and 8.0, withoccasional instances of up to 10.0 in August. In spring and summer, pools containingC. trichotoma had significantly higher oxygen readings(H005,6=7.9565, 0.01 <P <0.02) than E. compressa or barren pools, likely the result of enhanced photosyntheticactivity. Although salinity was noted to be highly variable within and among pools, therange of values measured (mean ± sE.) did not differ significantly (Mann-WhitneyUo.05(2)6,=30, 0.05 <P < 0.1) among treatment types within any of the seasons.Similarly, water temperature was noted to vary only slightly within a single pool or amongpools, and would vary approximately with atmospheric conditions. None of the poolswas distinct in this variable (i.e., beyond the normal range of values found among allpools), and variation among pools during any given sampling day was rarely more than2- 3 °C. Expectedly, water temperature during the winter (January) sampling period wassignificantly lower than during either the spring or summer intervals. A summary of theseconditions is provided in Table 2.1.Abundances of Enteromorpha compressa, E. intestinalis and Cladophoratrichotoma were generally lower in January, when various encrusting species were moreapparent. While abundance of E. compressa rarely exceeded 30% coverage of thesubstratum in pools with or without T. californicus, the percent-cover of C. trichotomawas generally higher, averaging 42.1 ± 16.4% (all pools) in August.In January, T. caljfornicus population numbers were lowest in all treatment types(142.4 ± 183.2 individuals . L1)and disparity in copepod abundance among pools withversus without C. trichotoma is less evident in January than in either the May or Augustresults. Overall percent-cover of C. trichotoma was also lowest in January (15.8 ± 10.8%compared to 35.0 ± 25.5% in May and 42.1 ± 16.4% in August). Absolute percent-coverChapter 2: Response to Macroalgae 47TABLE 2.1. Summary of in situ conditions for pools containing 7’. californicus in Barkley Sound.Treatments (same-substrate pools) differing significantly from one another between samplingintervals indicated by [i]; Values differing significantly from other treatment types during thesame sampling interval indicated by [t] (Kruskal-Wallace H at P < 0.05). Values presented asmean± S.E.Treatments containing Enteromorpha compressa + E. intestinalisJANUARY, 1995 MAY, 1995PARAMETER SAMPLING SAMPLINGAUGUST, 1995SAMPLINGNo. pools sampledAvg. Air Temp. (°C)(range)Avg. Elevation (m)(range)Avg. Volume (m3)rangeAvg. pH(range)Avg. Oxygen (mg/L)(range)Avg. Pool Temp (°C)(range)Avg. Salinity (%o)(range)%-Cover of Enteromorpha(range)T. californicus/L’(range)19[1} 5.5±5.2(-4-10)3.8 ± 1.0(2.5- 6.7)0.9± 1.61(0.2- 5.0)7.4 ± 0.7(6.2-8.3)6.1 ± 1.4(3.5 - 7.8)[] 9.7± 0.8(9-12)17.9 ± 8.5(5.4-30.9)16.7 ± 13.6(5- 50)349 ± 705(33 - 2440)1917.2± 6.1(8-21)3.9 ± 0.7(2.8- 5.0)0.3±0.44(0.01- 0.40)8.4 ± 0.7(7.1 -9.5)5.7 ± 3.3(1.1-9.0)20.4 ± 4.2(10-25)52.2 ± 31.4(18.2 - 109)28.9 ± 28.6(5 - 90)1870± 1567(600 - 6800)1015.5 ± 7.3(10-25)3.8 ± 0.7(2.8 - 5.0)0.3 ± 1.83(0.03 - 3.66)7.8 ± 1.2(6.8 - 10.0)5.6 ± 2.11(1.6- 8.3)25.0 ± 3.4(20 - 32)32.7 ± 14.6(20-62.3)19.0 ± 24.6(5-17)1175 ± 578(650 - 2000)(continued)Individuals per liter of pool volume, inclusive of all life-history stages.Chapter 2: Response to Macroalgae 48TABLE 2.1. (continued)Treatments containing Cladophora trichotomaJANUARY, 1995 MAY, 1995 AUGUST, 1995PARAMETER SAMPLING SAMPLING SAMPLINGNo. pools sampled 12 18 12Avg.AirTemp.(°C) [] 5.5±5.2 17.2±6.1 15.5±7.3(range) (-4 - 10) (8 -21) (10 -25)Avg. Elevation (m) 3.6 ± 0.7 3.7 ± 1.2 3.6 ± 0.6(range) (2.6-5.0) (2.8-6.7) (2.5-4.5)Avg. Volume (m3) 1.3 ± 2.06 0.3 0.44 0.5 ± 0.80range (0.08- 5.46) (0.01 - 1.49) (0.02 -2.88)Avg.pH 7.1±0.3 7.5±0.4 7.4±0.9(range) (6.5-7.6) (7.0-8.1) (6.0-9.1)Avg. Oxygen(mgfL) 7.9± 1.1 11.0±2.6 8.9±0.7(range) (7.0 - 10.1) (7.0- 13.2) (8.5 - 10.7)Avg.PoolTemp(°C) [] 9.8±1.3 21.3±2.1 22.6±2.8(range) (8- 12) (16 - 25) (19 - 27)Avg. Salinity (%o) 27.3 ± 3,9 35.1 ± 10.1 35.5 ± 6.7(range) (16.9-31.1) (29.4-74.1) (29-52.8)%-CoverofCladophora 15.8± 10.8 35.0±25.5 42.1 ± 16.4(range) (5 - 40) (5 - 80) (20 - 70),fornicus/L** 84± 112 35± 103 0(range) (0 - 175) (0 - 333) (0 - 0)(continued)** Individuals per liter of poo1 volume, inclusive of all life-history stages.Chapter 2: Response to Macroalgae 49TABLE 2.1. (continued)Treatments without macroalgae.JANUARY, 1995PARAMETER SAMPLINGMAY, 1995SAMPLINGAUGUST, 1995SAMPLINGNo. pools sampledAvg. Air Temp. (°C)(range)Avg. Elevation (m)(range)Avg. Volume (m3)rangeAvg. pH(range)Avg. Oxygen (mgIL)(range)Avg. Pool Temp (°C)(range)Avg. Salinity (96o)(range)%-Cover of Algae(range)i: caltfornicusfL **(range)11[] 5.5±5.2(-4-10)3.9±1.4(1.5 -6.7)0.72 1.68(0.01 - 5.4)7.3 ± 0.5(6.5 -8.1)6.5± 1.6(4.5- 8.0)L1 9.7± 1.6(7-12)25.1 ± 6.5(9.2 - 30.7)[t] 0(0 - 0)78 124(0 - 344)1617.2 ± 6.1(8-21)4.2± 1.0(2.6-6.0)0.5 ± 1.12(0.1-3.91)7.0 0.7(6.0 - 8.0)7.5 + 0.9(6.2 - 8.6)21.5 ± 1.9(18-25)51.0 ± 34.6(6.1-125)8.8 ± 16.2 *(0 - 60)1742 ± 2002(133 -8229)1715.5 ± 7.3(10- 25)3.8 ± 1.0(2.6-6.7)0.8 ± 0.99(0.04 - 2.64)7.2 ± 0.7(6.2 - 8.5)4.1 ± 2.1(1.7-7.2)25.4 ± 2.7(20 - 29)39.5 ± 13.6(29.9 - 89.2)0.6 * 2.4*(0-10)534 342(0 - 1800)* Includes encrusting algal species not identffied in the context of this study.** Individuals per liter of pool volume, inclusive of all life-history stages.1•Chapter 2: Response to Macroalgae 50did not differ with season for either C. trichotoma or E. compressa, and an inversecorrelation is evident only between C. trichotoma and T. californicus abundance(Pearson’s coefficient = -0.986, P < 0.05 over all seasons).Despite the apparent similarity between the chemical, physical and phycologicalfeatures of the pools, only those pools containing C. trichotoma retained lowerabundances of T. californicus, regardless of life-history stage and particularly in May andAugust (mean 35± 103 and 84± 112 individuals • L1, respectively, from Table 2.1).Mean values rounded to the nearest whole individual). Pools containing C. trichotoinaduring May sampling also showed a higher density of littorines (Littorina spp., at 10 ± 2.310 cm-2)than either E. compressa pools or barren pools (4±3.5 10 cm2 and 2 ± 5.4 10cm2,respectively; Mann-Whitney U values significant at 0.02 <P < 0.05). Larger,vegetated poois more frequently contained gammarild amphipods and isopods, howeverthe occurrence of other invertebrates (shore crabs, limpets, Chthamalus and Balanusbarnacles) or incidental vertebrates (mink, deer, shore birds) was too infrequent in thefield sites to derive any reliable statistical analyses.Field Results: Expectedly, copepod abundance was found to be extremely‘patchy,’ with high variances confounding analyses for statistical difference betweentreatments (Table 2.1). The response of copepod populations following inoculation ofsplashpools of all treatment types is summarized in Figure 2.1, and by life-history stage inC. trichotoma pools in Figure 2.2. Juvenile and adult copepodite stages (C-I to C-VI)demonstrated the greatest decline in overall number, while nauplius response (stages N-Ito N-VI) was highly variable but consistent regardless of pool type. Whether this wasdue to actual numbers or sampling error cannot be determined due to the difficulty ofcollecting, handling and identifying the nauplil in situ.Laboratory Results: Results from the laboratory microcosms are summarized inTable 2.2 and Figure 2.3. After five days of observation, the microcosms containingC. trichotoma retained fewer (18.6 ± 7.3 %-survival) copepodites and adult T.Chapter 2: Response to Macroalgae 51cahfornicus (stages C-I to C-VT) than other treatments(H005,6’=8.34; 0.005 <P <0.01). In microcosms inoculated with nauplii only (stages N-I to N-VI), no statisticaldifference was noted between treatments. After five days, the more advanced naupliibegan molting to copepodites and were transferred to a separate culture where theyappeared to mature normally.Figure 2.3 summarizes the average response of T. cahfornicus to the presence ofC. trichoroma in the six laboratory microcosms. Here, the effects of wind, precipitation,and wave splash are removed, and under-sampling of any life stages is unlikely, given thesmaller, controlled volume. (Error may be introduced, however, as individuals aredamaged or lost with the repeated transfer of solution for observation purposes.) Onceagain, the most significant deleterious effects can be seen among adult (stages C-TV toC-VT) T californicus, including the complete mortality of all gravid females in themicrocosms. While the net decrease in population is similar to that noted in the fieldtreatments, the most substantive decline in microcosm T calfornicus was not noted untilDay 3-4, compared to Day 0-1 in field treatments. As with the field sites, the overallnumber of nauplii in the microcosms, somewhat variable in initial abundance, remained atessentially similar levels throughout the period of observation.Chapter 2: Response to Macroalgae 52FIGURE 2.1. Response of Tigriopus californicus field populations to the presence ofsplashpool algae. Treatments contained either Enteromorpha compressa+ intestinalis,Cladophora trichotoma, or no algal material. Results are the average of 6 pools of eachsubstrate type following inoculation of T. californicus in May and August, 1995. As aplot of averaged results, error bars represent standard error of the mean (s.E.).Figure 2.1. Response of Tigriopus caIfornicusField Populations to Splashpool Macroalgae60050040030020010001 2 3 4 5 6Duration (Days)Chapter 2: Response to Macroalgae 53TABLE 2.2. Five-day population response of T. californicus in microcosms containingE. compressa, C. trichotoma or lacking algal material. Significantly lower survivorshipby treatment type indicated by [t] (Kruskal-Wallace H at P < 0.05). Values presented asmean ± S.E.Microcosms containing Enteromorpha compressa + intestinalis.Microcosm count T. californicus nauplil T. calfornicus copepodltes+adults(Avg. of 6 treatments) (stages N-I to N-YI) (stages C-I to C-VI)Initial count (individuals/L) 78±9.4 162 ± 8.9Count after 5 days 71 152net gainl(loss) (7 ± 2.2) (10 ± 1.1)% gain /(loss) (9.0± 2.2) (6.2± 1.1)%survival 91.0± 3.8 93.8±5.4Microcosms containing Cladophora trichotoma.Microcosm count 7’. calfornkus naupill T. californicus copepodites+adults(Avg. of 6 treatments) (stages N-I to N-VI) (stages C-I to C-VI)Initial count (individuals/L) 50±4.6 140 ± 6.1Count after 5 days 41 [tI 26net gainl(loss) (9 ± 5.3) (114 ± 9.2)% gain /(loss) (18.0 ± 5.3) (81.4 ± 9.2)% survival 82.0 ± 6.2 [f] 18.6 ± 7.3Microcosms without macroalgae.Microcosm count T. coi!fornicus nauplil 7’. cal4fornicus copepodltes+adults(Avg. of 6 treatments) (stages N-I to N-VI) (stages C-I to C-YE)Initial count (individuals/L) 42±3.9 178 ± 9.2Countafter5 days 35 180net gain/(loss) (7 ± 6.3) 2± 1.0%gain/(loss) (16.7± 6.3) 1.1 ± 1.0% survival 87.2 ± 0.03 95.6 ± 0.1Chapter 2: Response to Macroalgae 54Figure 2.2. Tigriopus caljfornicus Response FollowingInoculation of Cladophora trichotoma PoolsDuration (Days)FiGURE 2.2. Tigriopus calfornicus response following inoculation of Cladophoratrichotoma pools. As plotted, ‘nauplii’ = stages N-I to N-VI; ‘male’ and ‘female’ = stagesC-I to C-VI, where gender could be established. As a plot of averaged results, error barsrepresent standard error of the mean (SE.).150• males0 females• ovig. females-- - nauplii01 2 3 4 5 6Chapter 2: Response to Macroalgae 55Figure 2.3. Tigriopus ca1fornicus Response to the Presence ofCladophora trichotoma in Laboratory Culture50FIGURE 2.3. TigrEopus calfornicus response to the presence of Cladophora trichotomain laboratory microcosms. Note that while the net response is similar to that observed insitu (Figure 2.2), the most rapid decline in abundance occurs later following inoculation.As plotted, ‘nauplii’ = stages N-I to N-VI; ‘male’ and ‘female’ stages C-I to C-VI, wheregender could be determined. As a plot of averaged results for 6 x 500 mL, error barsrepresent standard error of the mean (SE.).200150I 0001 2 3 4 5 6Duration (Days)Chapter 2: Response to Macroalgae 56DIscussioNOn first consideration, the co-occurrence of TigrEopus ca4fornicus with densegrowths of supralittoral macroalgae would seem an ideal mutualism: The copepodswould receive protection from exposure and predation, oxygen from photosynthesis, anda supply of dissolved organic matter and bacteria associated with the algas surface. Inexchange, the algae receive the benefit of nitrogen excreted from the copepods,principally in the form of ammonia (89.7% of the total nitrogen excreted and estimated at27.2 tg N mg dry wr4 day-1 at 15°C for adult female T brevicornis, per Harris, 1973).As mentioned above, several factors must be considered in attempting to resolve why Tcalifornicus does not appear to co-occur with C. trichotoma, including: 1) unique waterconditions in pools containing C. trichotoma; 2) comparative degree of pool exposure towaves; 3) coincident fauna, particularly potential predators of either nauplii or juvenile(copepodite) life-history stages; 4) food supply; and 5) the survival and persistence oflarval life-history stages.Water Conditions: The range and variation of water properties measured in thisstudy are comparable to previously-published values for supralittoral pools (Morris andTaylor, 1983; examples in Metaxas and Scheibling, 1993). Pools containingC. trichotoma demonstrated no unique properties other than oxygen partial pressure(though admittedly, parameters more indicative of water condition such as levels ofnitrate, phosphate, microflora or phytobenthos were not included in the current analysis).That enhanced oxygen content alone is somehow toxic to T. calfornicus is unlikely,given the relatively large surface area of the splashpools (4.8 ± 10.9 m2 over an averagedepth of 7 ± 3.2 cm). The values of 1.2 to 13 mg oxygen recorded here compare to“non-lethal” oxygen levels reported by Kontogiannis and Barnett (1973), whose resultssuggest instead that T cahfornicus can be impaired by a reduction in oxygen partialChapter 2: Response to Macroalgae 57pressure (as by obstruction of the pool surface/atmosphere interface), an effect that mightbe even more significant at high population densities.Comparative Exposure: Although the intertidal distribution of Enteromorpha,Cladophora and Tigriopus may overlap (Fraser, 1936a; Gustavsson, 1972; Dethier,1980), Cladophora is generally found lower on the shore (Guberlet, 1956; Scagel, 1957;Waaland, 1977). The relatively greater exposure of the lower C. trichotoma poois towave splash may in part explain the absence of copepods from these poois, which concurswith published observations including Igarashi (1959), Vittor (1971), and Dethier (1980).Igarashi (1959) noted an inverse correlation between the age and stability of Tigriopus (Iassume japonicus) populations and the frequency of wave wash. Tigriopus copepods arenot noted to be strong swimmers (e.g., Fraser, 1936a, and pers obs.), are an attractiveprey item to fish and invertebrate predators (Dethier, 1980) and as a result may notremain long in the water column.Although wave exposure was not measured directly in the current study, amongpools 1) within a few meters of each other; 2) at the same elevation; and 3) differingvisibly only in the type of vegetation, only those pools containing C. trichotoma retainedsignificantly fewer copepods. A similar trend was also observed among pools of greateror lesser elevation and/or exposure to wave action, but whether the loss of copepods fromthose pools was alternately due to hydrodynamic consequences, surficial features, orfiner-scale differences in wave activity is not clear. From observations of cultureorganisms (Chapter 4), T. calfornicus does not exhibit self-directed swimming until theN-ffl stage (diameter 100 - 200 lIm), and may therefore be more susceptible to otherinfluences, such as wash-out by waves, cannibalism, or predation during the first few daysafter hatching.Although T. californicus populations also declined in the presence of Cladophorain laboratory microcosms, the effect was delayed (to Day 3-4) over that noted in fieldtreatments (Day 0-1). The decline in the number of copepods (especially adults) in theChapter 2: Response to Macroalgae 58absence of wave splash or atmospheric effects suggests the action of a secondarydeleterious agent on these life-history stages. The overall decline in copepod populationsintroduced to Cladophora pools in situ is likely due to the additional influences of: 1)under-sampling of copepods from the larger, irregular volume; 2) relatively greater waveaction on the generally lower C. trichotoma pools; and 3) the transport of adult T.californicus out of C trichotoma pools either passively by wave wash, or actively byswimming or crawling. Egloff (1966) also proposed ‘hitch-hiking’ on the carapaces ofgrapsid or pagurid crabs as a means of T. califomicus transport between poois, asuggestion reiterated by Dethier (1980) and Burton and Feldman (1981), but seeChapter 1.Coincident Fauna: The significantly greater number of littorines in C. trichotomapools may provide either competition to or predation on T. californicus populations. Itis not known whether littorines or barnacles cull Tigriopus populations by grazing naupliifrom the bottom of the pools or filtering them from the water column. Though present inmuch smaller numbers, amphipods may also consume T. californicus, however pools areroutinely found with thriving copepod populations despite the additional presence ofamphipods, isopods and even sculpins, particularly during the summer months (Chapter1). Littorines are also commonly found with T. californicus in non-vegetated andcomparatively sheltered Enteromorpha poois, though in lesser numbers. Given theremarkable densities at which T. californicus may be found (up to 200,000 L1, fromChapter 3), it is unlikely that other meiofauna are out-competing T. californicus for somecommon food resource. That littorines are responsible for producing the substanceapparently noxious to copepods is not supported by the laboratory results, where snailswere excluded from all microcosms yet the T. californicus populations declined.Nutrient Supply: The macroalgae present are probably inconsequential as a foodresource for T. californicus. An examination of the gnathobase and mandibles (seeEgloff, 1966, p. 11) suggests that T. californicus is not an herbivore or filter-feeder, butChapter 2: Response to Macroalgae 59most closely approximates the ‘prey-crusher’ variety described by Marcotte (1977) anddiscussed in Hicks and Coull (1983) Given this, T. califorizicus most likely browses anyavailable surface, feeding on a mixture of benthic diatoms and bacteria (cf Provasoli etal., 1959, for laboratory culture). Any substrate which encourages the growth of benthicmicroflora by: 1) the accumulation of organic debris; 2) enhancing the available surfacearea, or 3) having lesser accumulations of sedimentary material would therefore suit T.californicus for the provision of food. This suggestion is particularly relevant when oneconsiders the diversity of ‘food’ provided to T californicus in laboratory cultures,including Platymonas (=Tetraselmis)(Lear and Oppenheimer, 1962), Oscillatoria, RatChow® (Huizinga, 1971), boiled wheat, unicellular algae (Lazzaretto et al., 1990) andcommercial fish food or multigrain bread (see Chapter 4) Surfaces for microfiora growthare provided in situ by the incised and pitted bedrock which forms the supralittoral pools,by the surface of encrusting algae, or the longer filaments of algae such as Enteromorphacompressa and Scytosiphon lomentaria. The small size of C. trichotoma filaments (up to1.0 x 0.2 mm) may possibly be unsuitable for the growth of the particular microfloraT calfornicus may browse.Effect on Recruitment: The effect of chiorophytic algae on immature (stage N-Ito N-VI) T. calfornicus is difficult to discern. In the lab, the results may be biased by thefragility of the eggs and damage in the handling process. In the field, nauplii are very hardto find and may be underrepresented in sampling. While nauplii appear to becomparatively unaffected by C. trichotoma, the generally lower tidal elevation of thesepools may result in more frequent flushing by wave arid tidal inundation, as well as theenhanced potential for filtration or grazing by the increased numbers of sessile and motileorganisms occupying pools less frequently emmersed at low tide.Chemically-MediatedBehavior: Frequently, species gregariousness, thepalatability of a food item or suitability of an attachment surface may be determined bythe recruitment or “pre-conditioning” of microorganisms (e.g., ZoBell and Allen, 1935;Chapter 2: Response to Macroalgae 60Ryland, 1959; Crisp and Meadows, 1962, and the citations in that study; Shaw, 1994).Chemical exudates may even determine substrate selection to a greater extent than moreobvious surficial features such as form or texture (Crisp and Meadows, 1962). However,fluid flow may reduce the diffusive influence of a chemical secretion to that of a boundarylayer narrower than the diameter of a single larva, hence larvae may have to physicallytouch a given surface before detecting the exudates permeating it. Although the senseorgans of very small organisms may be too close together to detect the source ordirection of a chemical emission, behavior may still be elicited if a suitable thresholdconcentration is surpassed (Crisp and Meadows, 1962).From the current microcosm results, the presence of C. trichotoma appears toparticularly affect the copepodite stages (C-I to C-VT) of T californicus populations.Laboratory microcosms with C. trichotoma provided a lower overall number of survivingindividuals, while natural C. trichotoma pools retained lower proportions of gravid Tcahfornicus females. It may also be possible that the ‘toxicity’ of food resources are arelative consideration, determined by the acclimation of a short-lived organism to theconditions in which it is reared.If Cladophora trichotoma does produce some compound which is unpalatable,toxic to, or metabolically incompatible with T cahfornicus, a similar response is notnoted in littorines, which are found more abundantly in C. trichotoma pools than in eitherof the other pool categories investigated. While a lesser degree of desiccation and moreabundant vegetation undoubtedly enhances the suitability of lower pools for littorines, thisobservation does not support the conclusion that C. trichotoma produces some genericcompound intended to reduce grazing pressure. As described in Shaw (1994), a true antifeedant, while acting principally to reduce grazing pressure, is not necessarily lethal to thegrazing organism. Two observations in the current study then contradict the traditionaldesignation of anri-feedant for the agent potentially produced by C. trichotoma: 1) theagent does not apparently inhibit the presence (hence potential grazing pressure) ofChapter 2: Response to Macroalgae 61grazing meiofauna such as littorines; and 2) the agent exhibits a distinctly lethal effect onat least some life-history stages of T. californicus. The apparent deleterious effect of C.trichotoma turfs on T. californicus abundance may alternately or additionally be the resultof the kind of microflora which better grows on C. trichotoma filaments (see above), oran indirect physiological reaction of T. californicus to C. trichotoma exudates. Until amore complete isolation and analysis can be performed, the tenn crustacean deterrentmay better describe this agent.CONCLUSIONSThe supralittoral harpacticoid copepod Tigriopus cahfornicus does not maintainpopulations in splashpools containing the macroalga Cladophora trichotoma. Copepodpopulations in situ may be culled by incidental littorine grazing in C. trichotoma pools, orby enhanced wave action on these pools, which are of a slightly lower tidal elevation.Aliernately, the opportunistic C. trichotoma may overgrow or interfere with the substratawhich ordinarily provide a food source (benthic diatoms and bacteria) for T. californicus.The results of the current study additionally suggest that C. trichotoma may emit asubstance which is particularly noxious to the adult copepods. Among field sites withequivalent location and elevation, degree of wave exposure, pool volume and algalpercent-coverage, those pools containing C. trichotoma retained significantly fewer adultT. californicus; a trend which was also reflected in laboratory microcosms. However, theoverall influence of such an agent, if extant, is countered by the apparent lack of a similareffect on the survival of the early life stages, as observed in laboratory microcosms. Theobserved absence of T. californicus in poois which contain C. trichotoma appears to beprincipally the result of deleterious effects on the adult stages, since maintenance of thepopulation is ultimately dependent on the reproductive success of mature individuals.CHAPTER 3: DEsIccATIoN RESISTANCE IN TIGRIOPIJS CAUFORNICUSINTRODUCTIONMedia vita in morte sum,us(“In the midst of life we are in death”)— ST. GALL MoNKsThe existence of dormant or suspended life-history stages among crustaceans isnot uncommon; the most obvious example is the marketing of freeze-dried brine shrimp(Artemia spp.) as “sea monkies” and wind dispersal of dormant Artemia eggs is noted inBrown and Gibson (1983). The literature specific to the harpacticoid copepod genusTigriopus includes several accounts of ostensibly re-animated individuals. Fraser (1935)described free-living T. fulvus individuals arising from a bottled water sample which hadbeen sealed for more than 18 months. Fraser (1936) translated the description of Issel(1914), that“as soon as the density of the water reaches a certain degree the copepodT. fulvus falls into a state of apparent death, from which it can awake evenafter a very long time and regain normal activity when the water issufficiently diluted.”This observation was tested experimentally by Ranade (1957), who described the “state ofapparent death” (p. 119) in T. fulvus at salinities in excess of 90%o; a condition whichcould be reversed by transferring the organism to lower salinities. Ranade (1957) alsofound a positive correlation between exposure to higher salinities and the lethaltemperature for T. fulvus. Egloff (1966) found all life-history stages of Tigriopuscalifornicus to endure 100% relative humidity for up to 30 minutes. Further, althoughegg sacs survived equally well at 60% relative humidity, nauplii and adult survival werereduced by more than 50% over the same duration. Kasaliara and Akiyama (1976)62Chapter 3: Desiccation Resistance 63cursorily described the dormancy in adult stages of T. japonicus, however Vittor (1971)found none of T. cabjornicus’ life-history stages able to survive prolonged desiccation.Conversely, Dybdahi (1994, p. 114) stated that T calfornicus “lacks desiccation-resistantdormancy or diapause stages,” and that 35% of pools may experience extinction over sixto eight weeks (italics mine), but cites no conclusive evidence for these assertions.Dybdahl (1994, p. 115) also reported the presence ofT. calfornicus in “a quiescent state”in moistened rock crevices, a behavior also described for T fulvus by Ranade (1957).Uniformly, casual reports of desiccation resistance in Tigriopus omit crucialinformation needed to interpret the possible mechanisms involved. Specifically, thisincludes: 1) a description of water conditions (volume, temperature, salinity or microflorapresent); 2) the life-history stage(s) involved; or 3) the time interval over which reanimated activity is observed. The latter two observations are critical to understandingthe mechanism of the copepod’s dormancy: At 20°C, T calfornicus requires about 10days to mature from egg to the first copepodite (C-I) stage and a further 11 days tomature to the C-VT stage adult (Chapter 4). Hence, if nauplii (stages N-I to N-VT) areobserved within a few days of splashpool re-hydration, the existence of dormant orencysted eggs is suggested; if more mature (C-I to C-VT) stages are observed, theorganism’s propagation is likely provided by suspended copepodites or adults.The average occurrence ofT cahfornicus is in splashpools at a level 3.6 m abovemean water level (MVTL), therefore only infrequently influenced by tidal activity andstorm waves. The pools typically provide a large surface area and are 2 to 25 L involume with a “water column” of 5 to 15 cm (Chapter 1). From Chapters 1 and 2,macroalgae common to the supralittoral zone in Barkley Sound include Cladophoratrichotoma, Scytosiphon lomentaria/Ralfsiapac/ica and Enteromorpha compressa, E.intestinalis and Hildenbrandia spp. The filamentous Scytosiphon and Enteromorpha mayprovide a source of dissolved organic material and naviculoid diatoms for T ca4fornicus,or a refuge from predation or exposure to the elements.Chapter 3: Desiccation Resistance 64Shallow, small volume pools are more directly influenced by atmospheric - ratherthan oceanographic - processes, and air temperature can provide a reasonable estimate ofpool water temperature (e.g., Egloff, 1966, but see Morris and Taylor, 1983). At thesame time, orientation, aspect, shading and rock coloration all provide pool-specific waterproperties and responses to evaporation, and replicate field sites must be selectedcarefully (Metaxas and Scheibling, 1993).Within such a severe, highly variable, and discontinuous habitat, the distributionand occurrence of Tigriopus caljfornicus is expectedly irregular or patchy. Althoughconditions will vary with season and location, complete evaporation of these pools or thedecimation of a resident Tigriopus population by wave wash are undoubtedly frequentoccurrences. Harris (1973) estimated the life span of T. brevicornis to be 55 days at15°C, while ItO (1970) provided a longevity estimate of 70 days for 7’. japonicus. Vittor(1971) derived an estimate (to 10% survival) of 130 ± 14 days at 15°C for T.californicus, a value which decreased to Ca. 80 days at 25°C. The same study provided ageneration time of 32 days at 15°C, which reduced to 18 days at 25°C. It is thereforeeasy to speculate that any given splashpool may evaporate at least once, and perhapsseveral times, over the course of a single copepod generation. See Chapters 4 and 5 for amore detailed discussion.Vittor (1971) and my own observations have not found T. californicus innearshore plankton samples, however accurate sampling of possible “source” populationsfrom such dynamic coastlines is not easily done. For a copepod, inter-pool dispersal,migration, or simply being deposited from the coastal maelstrom into a basin whichprovides food resources as well as sufficient refuge must prove equally daunting (seeChapter 1). With these considerations in mind, the chapter study attempts to quantify theability ofT. californicus to tolerate desiccation and thus demonstrate a plausiblemechanism for intra-pool colonization following intervals of complete evaporation. SuchChapter 3: Desiccation Resistance 65a mechanism would also account, in part, for the observed incidences of outbreedingdepression and genetic heterogeneity between outcrops (per Burton, 1990; Brown, 1991).MATERIALS AND METHODSField Sites: All pools were selected from tagged sites monitored in 1994 and1995 on Helby Island, British Columbia (Lat. 48°51’N: Long. 1250 10.5W), situated insoutheast Barkley Sound (Figure 1.1). From these, 12 pools were selected usingstratified random sampling, for: 1) similarity in intertidal elevation (between 4.0 and 4.5m above MWL); 2) similarity of exposure (arbitrarily based on orientation and availablewind breaks), and 3) the presence of Tigriopus californicus in the dried substratematerial. All pools were within 60 m of each other and had completely evaporated (dryto the touch) following four to five days of warm weather, calm conditions and anabsence of tidal inundation. Given the proximity and similarity of the pools selected, andlacking any observations to the contrary, similar atmospheric influences and dryingperiods for all replicates was assumed. Rates of evaporation for all pools were calculatedby measuring the depth and perimeter of the pools each day using a consistent set oflandmarks. Except for intermittent onshore winds, atmospheric conditions remainedconsistent during the experiment: no cloud cover, precipitation or tidal inundation and amean air temperature of 12.7°C.Six pools contained dried mats of the green macroalgae Enteromorpha compressa(Linnaeus) Grevifie (Guberlet, 1956), and six contained deposits of mixed sedimentcomprised of detritus, phytobenthos and inorganic material. Three pools of eachsubstrate type were then hydrated using collected rain water (average volume 8 L, salinityO.8% at 15°C) and three with natural sea water passed through a 100 p.m filter (averagevolume 7 L, salinity 31.4% at 15°C) and observed for seven days. Water was drawnfrom field sites using a 30 mL pipette (sampled volumes were replaced), and the numberChapter 3: Desiccation Resistance 66and stage of copepods in each sample determined using a dissecting microscope andidentification key (Monk, 1941, and Chapter 5).Lahoratory Treatments: Concurrent with the field manipulations, samples ofdried substrate material were taken from the same pools and allocated to an equivalentnumber of laboratory beakers (microcosms) and hydrated with 200 mL of either rainwater or filtered sea water from the same sources. Due to availability, the average dryweight of E. compressa provided was 3.4 g, and of flaked sediment was 0.5 g pertreatment.Microcosms were maintained, uncovered, in a sheltered, outdoor location andobserved for seven days, or until no further response was noted. Culture flasks areusually loosely covered to reduce evaporation; however none of the microcosmsexperienced significant evaporation, and provided a better comparison to field conditions.Enlivened copepods were removed from the microcosms each day, narcotized by 10%dilution with carbonated water (Gannon and Gannon, 1975)and identified by key as male,female, copepodites, or nauplil. Copepods were then monitored in a separate flask todetermine the net increase in individuals from each treatment after seven and 14 days.Copepods which still did not respond to gentle agitation were counted and identified, asabove, to provide a census of the source population (i.e., the total number of copepodssuspended in each dried substrate sample; Table 3.1).A quantity of each substrate material was also retained at room temperature for afurther 10 days, providing a sample of suspended copepods which had not seen anymoisture for 14 days (= four days of field evaporation, then 10 days sequestered in thelab), or approximately one tidal cycle.Using the same methods, dried samples were also re-hydrated using ordinary tapwater. Several trials were also performed using available dried algal material which hadbeen stored for up to 15 months. Individuals which were successfully enlivened wereeither: 1) collected and dried again (to the touch) to test for possible repeated animationChapter 3: Desiccation Resistance 67response; 2) retained and observed in laboratory culture; or 3) sacrificed with 5%formaldehyde solution and examined to confirm identifications.Treatments were compared for: 1) abundance of copepods in source material; 2)percentage of copepods re-animated; and 3) net gain in individuals using a one-wayrepeated measures Analysis of Variance (ANOVA). Where treatments differedsignificantly (c = 0.05; P <0.1), a Student-Newman-Keuls analysis was performed on allpair-wise multiple comparisons (Zar, 1984; Jandel, 1994).RESULTSCalculations derived from the field sites used in this experiment yielded an averagevalue of 2.3 L m2 day-1 for surface evaporation under relatively calm conditions.This value increased to 3.4 L rn2 day-1 under the influence of wind.The re-animation response ofT calfornicus under conditions of rain water andsea water addition are summarized in Tables 3.1 and 3.2, and Figure 3 1. Overall, thetreatments showed consistent results between field pools and laboratory microcosms.The samples treated with either rain water or sea water, containing Enteromorpha ormixed sediment did not differ between field pools and cultures.Source Material: The dried treatments containing Enteromorpha showed asimilar abundance of individuals per gram of substrate as sediment treatments (576copepods g1 and 494 copepods g, respectively). Whether this was due to: 1)copepod attraction to a potential food source or retained moisture; or 2) the number ofindividuals in the original (pre-evaporation) population could not be determined. Therewas also no significant difference in the number of individuals retained by each sedimenttype, as compared between samples used in the laboratory microcosms and samples takenseparately from the field sites.Chapter 3: Desiccation Resistance 68TABLE 3.1. Tigriopus cahfornicus response following re-hydration of dried substratematerial with either rain water or filtered sea water. Percentages are derived from theproportion of individuals enlivened per number of individuals present per gram ofsubstrate material. Numbers in parentheses refer to the total number of individualsenlivened per the total number counted for each treatment type. Results tabulated forn =3 pools and n = 3 microcosms.Mixed sediment,rain water hydrationOvigerous femaleMaleFemaleCopepodite StagesNauplii/eggOverallSE.19.25 (41/2 13)9.80 (14/143)14.61 (26/178)22.22 (2/9)0.00 (0/8)15.06 (83/55 1)8.740.00 (0/10)0.00 (0/92)0.00 (0/24)0.00 (0/4)0.00 (0/0)0.00 (0/130)0.00N/ASubstrate! 1’. calfornicus % re-animated ( #/counted) fromWater Type life history stage Field Pools Laboratory CultureOvigerous female 35.68 (76/213) 31.82 (7/22)Male 20.62 (40/194) 7.07 (13/184)Female 17.06 (29/170) 7.32 (9/123)Enterornorpha, Copepodite Stages 21.33 (16/75) 20.00 (1/5)sea water hydration Nauplii/egg 20.00 (2/10) 33.33 (1/3)Overall 24.62 (163/662) 9.20 (3 1/337)SE. 7.31 12.70Max. response on Day 2 1Ovigerous female 22.69 (54/238) 10,42 (10/96)Male 14.34 (74/516) 8.82 (12/136)Female 26.03 (38/146) 11.11 (4/36)Mixed Sediment, Copepodite Stages 55.00 (22/40) 0.00 (0/10)sea water hydration Naupliilegg 14.29 (8/56) 0.00 (0/10)Overall 19.48 (196/1006) 9.03 (26/288)SE. 16.76 5.60Max. response on Day 3 1Ovigerous female 2.17 (6/276) 7.41 (6/81)Male 1.76 (6/341) 5.96 (18/302)Female 5.71 (6/105) 3.55 (6/169)Enteromorpha, Copepodite Stages 0.00 (0/16) 12.50 (1/8)rain water hydration Nauplii/egg 0.00 (0/4) 0.00 (0/1)Overall 2.43 (18/742) 5.53 (31/561)SE. 2.34 4.64Max. response on Day 2 5Max. response on Day 1Chapter 3: Desiccation Resistance 69TABLE 3.2. Net increase in Tigriopus calfornicus life-history stages after one week ofobservation. Since the mass of dried material and overall population response in fieldpools could not be accurately determined, the values expressed are from the laboratorymicrocosms only. Net increase is expressed as the number of individuals reared per gramof dried substrate.Substrate IWater TypeMixed sediment,rain water hydrationT. calVornicuslife history stageOvigerous femaleMaleFemaleCopepodite StagesNaupliiJeggMeanNet increase (# of individualsper gram of substrate material)in I Week0000000Ovigerous female 2.4Male 4.2Female 3.1Enteroinorpha. Copepodite Stages 0.3sea water hydration Nauplii/egg 0.6Mean 3.2S.E. 2.1Ovigerous female 3.4Male 2.6Female 1.4Mixed Sediment, Copepodite Stages 0sea water hydration Naupliilegg 0Mean 1.5SE. 1.5Ovigerous female 2.1Male 6.0Female 2.1Enterornorpha, Copepodite Stages .7rain water hydration NaupliiJegg 0.2Mean 2.2SE. 2.3SE.Chapter 3: Desiccation Resistance 70FIGURE 3.1. Tigriopus ca4fornicus life-history stage response to hydration in laboratoryculture. The response between substrate types and field-versus-laboratory samples didnot differ statistically, and the in situ population response could not be accuratelymonitored. For clarity, results are presented as the mean response of all laboratorytreatments, for each life-history stage.Figure 3.1. Tigriopus cahfornicus Life-History Stage Response toHydration in LaboratoryCulture76• ovig. females• malesA femalescopepodites-- -- nauplii—1I-25 6 7Duration (Days)Chapter 3: Desiccation Resistance 71Percent Re-animation: The sediment/sea water treatments showed a significantlyhigher percentage of animated individuals, a result which could have been due to anunder-sampling of source’ individuals in the laboratory specimens, or (in one instance) theaccidental introduction of individuals from adjoining pools which had not evaporated.Net Gain ofIndividuals: The Enteromorpha treatments showed a higherpercentage and net gain of individuals, particularly with re-hydration using sea water.However, the net increase was not significant with the one-way ANOVA at a = 0.05;P < 0.1). Overall, the presence of sea water appeared to have a more significant influenceon the response of cultures than the substrate type.Using the abbreviations L (lab culture), F (field) / E (Enteromorpha), S (sediment)/ SW (sea water), RW (rain water), the re-animation response for all treatments, scaledfor volume and mass of sediment material and ranked from lowest to highest was:L/S/RW < F/E/RW < L/S/SW < L/E/RW < F/S/RW < L/E/SW < F/S/SW < F/E/SWImmediacy ofResponse: From Figure 3.1, the maximum re-animation response inculture copepods occurred within 24 hours for all life-history stages, but particularlyovigerous females and adult males. A second net increase was noted during Day 2-3,with adult stages demonstrating similar gain/loss responses over the first five days. Nofurther enlivened individuals were noted after Day 5.Additional Results: Enlivened individuals were not observed from the driedsamples stored an additional 10 days (i.e., at least 14 days since last moistened). Whetherthis was the result of eventual death of the copepods or the quality of the dried samplescould not be determined.Attempts to re-animate dried samples using ordinary tap water were unsuccessful.Were even a very few enlivened individuals noted in these trials, a lack of bacteria in thewater might be suggested; a more obvious explanation is that the chlorine in the waterwas deleterious or lethal to the copepods.Chapter 3: Desiccation Resistance 72Re-hydration of dried algal material which had been shelf-stored was alsounsuccessful, probably due to: 1) an insufficient number of suspended copepods in thesamples available; and 2) the eventual, complete death of the copepods.Several attempts were also made at air-drying enlivened individuals, then rehydrating them again in either fresh or saline water. Only 2 of 27 individuals (7%) weresuccessfully revived in this way (one ovigerous female and one immature copepodite); thiswas probably due to the smaller proportion of copepods tested for repeated response.DIscussIoNUsing Tigriopus californicus populations as an example, the results of the currentstudy reveal at least three significant caveats for the study of populations of ephemeralsplashpools:1. Data collected and presented as individuals per volume sampled will not be sensitive tothe volumetric history of the pools. Since the pool volume may change rapidly (dueto precipitation, runoff or wave exposure), or gradually (by evaporation), eachsample can only be considered a snapshot of in situ conditions. Increased densitiesof individuals per volume sampled over time may not represent a ‘bloom’ in actualnumbers, but rather only a change in pool volume. A preferred method wouldpresent the data as individuals per unit pool volume at the time of sampling;2. Calculations of production, immigration, emigration, gene flow or metapopulationextinction must be sensitive to the, presence of individuals re-animated from asuspended state. As an average over all our treatments, such re-animation mayoccur to the extent of 10.7 ± 8.5% of all individuals; and3. Although the re-animation response appears to be quite consistent over all life-historystages, the net increase in individuals may be biased by disproportionaterepresentation of certain life-history stages (particularly ovigerous females and adultmales) in the source material.Chapter 3: Desiccation Resistance 73Dybdahi (1994) noted that sufficiently high tides to promote wave re-distributionof supralittoral pool water may only exist one or two days per month. From over a yearof our field data from Barkley Sound, an average-sized Tigriopus californicus pooi is10.5 L in volume and 0.24 m2 in surface area (Chapter 1). Based on calculations from thecurrent study on the rate of pooi evaporation, and lacking precipitation or tidalinfiltration, such a pool would be expected to evaporate completely within 7 to 8 days.Although spring conditions in Barkley Sound are notoriously damp (19.2 cmprecipitation, 14 year April average), prolonged dry conditions and high winds can beexperienced in all seasons. Thus, the frequency of complete pool evaporation is probablyquite high and, depending on the size of the pool, may be experienced by the resident T.cahfornicus population as often as four times per generation. Based on the currentresults, a pool which was re-hydrated as little as once per week could potentially maintaina population of T. californicus; two weeks’ duration between evaporation and rehydration would likely result in population extinction (see Chapter 5).Even low proportions of re-animated copepods may yield enough individuals toestablish a new population in a re-hydrated pool. Dybdahi (1994) estimates that 75% ofcolonizing T. californicus populations contain 10 or fewer individuals, an observationsimilar to those of Vittor (1971). Assuming an average re-animation response of 10.7 ±8.5% (mean ± s.E.) from all treatments, this would require a source of only 99 driedindividuals to produce 10 colonists, although slightly dependent on the gender and life-history stages present in the dried sample. If the same success rate is assumed constantfor a second re-hydration (7.4%), a source of 1340 individuals would be required toproduce 10 colonists after two evaporations. Both values are within reason for largeTigriopus populations locked in the substrate material of evaporated pools: Someconcentrated populations have approached 200,000 or more individuals L1; in a 7 Lpool, this would be over 1000 times the source population required to enliven 10colonists from two successive re-hydrations. At such densities, an average success rate ofChapter 3: Desiccation Resistance 74only 7.1 x 10-% would permit re-animation of a sufficient number of individuals tocolonize a pooi.Applying these results, approximately one-half of the re-animated individualswould be ovigerous females or other adult stages (Table 3.3). Under favorableconditions, this would provide a remarkable ‘at the ready’ potential for releasing eggs andrapid re-colonization from 50% of the colonists. The remaining re-animated individualswould be juvenile stages (copepodites or nauplii), reaching maturity in one to two weeks.The ultimate influence of these juvenile stages would depend upon the frequency ofcomplete desiccation. Further, I observed an average increase of 6.9 individuals• day-1re-animated from the microcosms containing Enteromorpha and an increase of 8individuals• day-1 from pools containing Enteromorpha. These values could reasonablycontribute up to 7% of the calculated increase in living T. caljfornicus populationsprovided by Dethier (1980). Her “0.2 individuals per 15 mL” (p.103) equates to 13 L1or 107 individuals, day-1 in a 7 L pool such as the treatments used in the current study.The inclusion of individuals from virtually all life-history stages further assures thestability and longevity of the population. Egloff (1966) found all life stages to be presenton the carapaces of crabs and proposed this as one possible means that Tigriopus mightuse to move between pools. The reliability of this is doubtful, however, since the crabsmay travel to lower or otherwise inhospitable intertidal sites, and are themselvesattractive targets for birds and other predators (see Chapter 1). Vittor (1971) described are-colonization response in T. calfornicus whereby there is a rapid increase in populationsize from a limited number of colonists. Tigriopus copepods are notorious for theirfecundity and efficiency of egg production (Egloff, 1966; Burton, 1985, forT. ca4fornicus; and Comita and Comita, 1966; Harris, 1973, for T. brevicornis) and asmall number of individuals of differing ages might quickly and effectively re-colonize apooi. From the current results, this process seems to require only sufficient moisture andthe provision of an adequate food resource. Also consistent with these results is theChapter 3: Desiccation Resistance 75TABLE 3.3. Differentiation of animated Tigriopus calfornicus as potential re-colonizersof hydrated pools. Approximately half of the sample would contain adult individuals,capable of immediate reproduction or egg deposition, while the remainder would bejuveniles reaching maturity in seven to 10 days.T. californicus Percentage (± S.E.) PresentLife-History Stage in Re-animated Sample Potential ResponseOvigerous Females 17.8 ± 2.02 Immediate deposition of eggs.Production of remaining broods.Adult Males 11.01 ± 1.57 Insemination of receptivefemales.Adult Females 13.64 ± 1.69 Reception of males.Production of eggs fromprevious insemination.Copepodites 18.82 ± 2.37 Rapid re-animation response.Maturation thin 1 week.Nauplii I eggs 12.49 ± 2.43 Maturation within 2 weeks.(Possibly less resistant to stress).Chapter 3: Desiccation Resistance 76observation in other studies that gene flow between neighboring pools of T cabjornicusis much more restricted than would be expected of organisms capable of dispersal livingin an unstable or stressful habitat (Burton, 1986, 1990; Brown, 1991).With the exception of the algae! rain water treatments, field populationsapparently responded better than laboratory populations to re-hydration. Rain water(salinity 0.8%o) added to dried Enteromorpha in our field sites achieved a final salinityof38.S%o, which compares to the sea water treatments. In contrast to Ranade (1957),the current results suggest that dilution effects alone were not responsible for the reanimation response. Rather, it is probably an artifact of 1) over-estimating the sourcepopulation; or 2) under-sampling enlivened individuals in the larger pools containingEnteroniorpha. It also suggests that with sufficient localized concentrations of salts,bacteria and detrital material, ordinary precipitation may accumulate these substances toproduce pool water that approximates sea water in its composition. In other words,whether the moisture is derived from wave action or precipitation, it may ultimately beequally as effective. It is also conceded that the actual dehydration of individuals was notdetermined. All ‘dried’ individuals were assumed to be equally desiccated by naturalconditions, which is doubtfully the case. A more appropriate description of dehydrationcould indicate changes in individual body volumes following hydration (per Wulif, 1972),however such handling may introduce other sources of error or damage suspendedspecimens.The comparatively better response of treatments provided both Enteromorpha andsea water may indicate the response of T cahfornicus to higher levels of bacteria,nutrients or trace metals. Tigriopus ca4fornicus is commonly found in the same pools assome macroalgae, while being entirely absent from pools containing other algal species(Chapter 2). Thriving populations are also observed in pools lacking any macroalgae orsediment. From this, and the observations of Chapter 1, the food source for fieldChapter 3: Desiccation Resistance 77populations is most likely bacteria or benthic diatoms, and both of these food types wouldbe provided either by tidal infiltration or precipitation.A series of qualitative observations yields the following proposed sequence ofevents during splashpool evaporation: As the water volume is decreased, the pool’sperimeter is reduced and irregularities in the basin may divide the pooi into sub-basins.Surviving T ca4fornicus congregate in these sub-basins, or take refuge in any moisture-retaining vegetation. At this time, concentrations of individuals exceed 200 mLsampled; values one to two orders of magnitude higher than previously published ‘high’ insitu densities (e.g., Fraser, 1935, for T. fulvus; Dethier, 1980, for T calfornicus;Igarashi, 1959, for T. japonicus). At this time, density-dependent responses such ascannibalism, maternal predation on nauplii or retention of egg sacs may predominate, asfound in T. japonicus (Kahan et al., 1988) and T. fulvus (Lazzaretto and Salvato, 1992).The result is an essentially adult population, as the production and survival of youngstages is greatly reduced.As the slight water column evaporates, adults settle out of solution atop theremaining copepodite and naupliar stages, which in turn seek the moisture retainedbetween the larger adults. Copepodites were re-animated the most quickly (within 15minutes in some instances), perhaps because of their larger surface area-to-body volumeratio relative to mature adults. Adult males and ovigerous females provided the greatestsuccess in re-animation, most likely due to their overwhelming representation in the driedmaterial (up to 62% and 40%, respectively).Kahan et al. (1988) observed that ovigerous T fulvus females apparently do notdrop their egg sacs in response to increased salinity. These authors also observed thatculture females sacrificed by a variety of means will release their eggs usually within anhour, and eggs removed from the female will hatch nearly immediately. The retention ofegg sacs by females in evaporated pools then poses an interesting question: how do thegravid females respond at the moment of their death and, accordingly, release their eggs?Chapter 3. Desiccation Resistance 78Whether by structural or hormonal modification, the retention of egg sacs by inanimatefemales may provide one clue as to whether they are suspended or in fact dead.Tigriopus californicus nauplii sampled from field populations in Barkley Soundare very much reduced from expected abundance in natural populations, which concurswith the observations of Harris (1973) for T brevicornis. Since I’. calfornicus naupliiare short-lived (from Chapter 5, about two days for each nauplius stage), they may bevery ephemeral in field populations. Cannibalism may further reduce these numbers, andthe preference of the nauplii to associate close to the bottom of pools undoubtedly alsoreduces their representation in samples; whether nauplii are captured by sampling may bea matter of timing (hence improved by an increased frequency of sampling). O’Brien et al.(1988) find the tolerance of T. calfornicus to cupric ion activity to be at a minimum forstages N-I through N-TV, and with the exception of eggs (which showed toleranceintermediate between the naupliar and copepodite stages), there appears to be a gradual,rather than sudden, increase in tolerance to cupric ion activity through to the C-VT adult.If these results are applied generally to pollutants, the carrying of eggs by suspendedadults may be one way for the less-resilient juvenile stages to avoid potentiallyinhospitable conditions at the time of re-hydration. Hence, the retention of eggs by thefemale may provide some assurance that young will be released only under favorableconditions.CONCLUSIONSThe copepod Tigriopus californicus has demonstrated the ability to recover fromretention in evaporated splashpools if the duration of this desiccation does not exceedseven to 10 days. The response to either fresh or saline hydration is nearly immediate,and is observed across all life-history stages, albeit proportionate to the body volume andrepresentation of these stages in the source sample. With the presence of continuedmoisture and food supply, re-animated individuals appear to be completely viable.Chapter 3: Desiccation Resistance 79Despite the low overall percentage of recovery observed, the response is likely adequateto promote the re-establishment of populations within pools.CHAPTER 4: DEVELOPMENT, BODY LENGTH, AND FEEDING OF TIGRIOPUSCALIFORNICIJS IN LABORATORY AND FIELD POPULATIONSINTRODUCTION“Growth is the only evidence of life.”—3. H. NEwMAN (1864)The natural abundance of harpacticoid copepods, as well as their small size,remarkable fecundity, short generation time, and tolerance to extreme or sudden fluxes inthe supporting aqueous medium are attributes that have served to promote their use inadiverse array of experimental applications. Examples specific to Tigriopus cahfornicusalone, include evaluations of copepod feeding (Lear and Oppenheimer, 1962; Sullivan andBisalpuira, 1980; Syvitski and Lewis, 1980) and suitability as food for cultured fish stocks(Morris, 1956; Fahey, 1964), response to pollutants or thermal and osmotic stress(Chipman, 1958; Huizinga, 1971; Kontogiannis, 1973; Kontogiannis and Bamett, 1973;McDonough and Stuffier, 1981; O’Brien et al., 1988; Misitano and Schiewe, 1990;Burton, 1991), sex determination and development (Vacquier and Belser, 1965; Egloff,1966; Palmer et al., 1993), fecundity (Burton, 1985); and genetics (Ohman, 1977; Burtonet aL, 1979; Burton and Swisher, 1984; Burton 1987,1990; Brown, 1991, to list only afew examples). Indeed, all Tigriopus congeners may claim an equal diversity ofapplications, but a catalog of these is beyond the intent of this thesis.The development of Tigriopusjaponicus has been described by Igarashi (1963a,1963b), and illustrated extensively by ItO (1970) and Koga (1970). Fraser (1936b) andBozic (1960) document the natural history and taxonomy of T. fulvus, respectively, whileComita and Comita (1966) and Harris (1973) provided the benchmark studies for the eggproduction, growth, and physiology of T. brevicornis. Burton (1985) detailed the matingsystem of T. califomicus and Huizinga (1971) discussed cursorily the development of80Chapter 4: Development, Size, andFeeding 81T calfornicus and maintenance of the organism in culture. A number of studies haveaddressed related population-level responses of Tigriopus copepods in laboratory culture,including dormancy of life-history stages (Fraser, 1935; Kasahara and Akiyama, 1976),development and brood production (Igarashi, 1960; Takano, 1971, which includes severalearly citations for T japonicus), and chemically-mediated behavior (Kahan et al., 1988;Kahan, 1992 for T japonicus; and Bone, 1975; Lazzaretto et al., 1990; Lazzaretto andSalvato, 1992 for T. fulvus). A satisfactory description of the life-history ofTcalfoniicus has not been published, despite the taxonomic description of Monk (1941),studies of field populations by Egloff (1966) and Vittor (1971), and analyses ofpopulation genetics by Burton et al. (1979), Brown (1991) and several more recentstudies by Burton. Inevitably, assumptions on the species’ development are drawn fromobservations made from its congeners, which may be sufficient for most, but not all,applications. Further, experimental results have frequently been presented with referenceonly to adults, eggs, or larval stages, with little mention of the life-stages categorically soincluded. No published studies have yet addressed the development of T. ca4fornicusunder conditions truly representative of the temperate, supralittoral splashpools that arethe organism’s natural habitat.The intent of the current chapter is to provide a synthesis of the foregoing studieswith my observations on the maintenance of T cahfornicus in culture. The organism’smorphological development under laboratory and seasonal in situ regimes will beevaluated, with particular consideration of water temperatures and salinity typical of theorganism’s natural environment.MATERIALS AN]) METHODSSpecimens of Tigriopus cahfornicus (Baker) were collected from field sites inBarkley Sound (Chapter 1) into 500 mL Nalgene bottles and maintained with theChapter 4: Development, Size, and Feeding 82following technique modified from Huizinga (1971) and Omori and Ikeda (1984):Samples were transferred in their natural pooi water into 2 L Erlenmeyer flasks, theneither: 1) maintained at 18 - 20°C and 32 - 35%o to approximate summer conditions; or 2)chilled (cold room or ice bath) at 10 - 15°C and 20 - 25%o salinity to approximate winterconditions. Temperatures and salinity selected were representative of seasonalconditions for the field sites (see Chapter 1). The volumes of all stock cultures weremaintained at approximately 1.5 L by replenishment with distilled, de-ionized water(DDW) to maintain consistency in the levels of bacteria, microalgae, and salt content; aPetri dish or watch glass was placed loosely over the mouth of all flasks to prevent undueevaporation.Cultures were also inoculated every seven to 10 days with 50 mg ofWardley’sBasic Fish Flakes® or a culture of mixed bacteria’ from the Northeast Pacific CultureCollection (University of British Columbia, Vancouver), as available. While the amountof nutritive material used to support ‘summer’ and winter’ cultures was the same, theseasonal in situ splashpool water undoubtedly differed in the taxa and initial abundance ofnatural bacteria and unicellular algae present (Lee and Taga, 1988; Metaxas and Lewis,1992; Carli et al., 1993).To evaluate the organism’s development, egg sacs were removed from gravidfemales and transferred individually to six-well plates kept at room temperature or chilled;water conditions as above. All wells were examined daily with a dissecting microscope orjewelers’ glass; añer hatching or molting, a selection of individuals (150 eggs, then 50 ofeach subsequent life-history stage) were removed from each tray and examined forexternal morphology and size (diameter or maximum length). Maximum length is heredefined as the straight line distance from the rostrum to the posterior terminus of thecaudal rami, or the equivalent position on juveniles (nauplii) where these structures haveyet to develop. Molted individuals were then transferred into new wells or sacrificed for1 The species composition of this culture was unavailable at the time of this writing.Chapter 4: Development, Size, and Feeding 83detailed examination at higher magnification under oil immersion. Slides were preparedfollowing the methods of Omori and Ikeda (1984): specimens were sacrificed with lacticacid, and stained for 30 to 60 mm in diluted chlorazol black E. Specimens were thenrinsed in benzyl alcohol and DDW and transferred to a drop of glycerin for dissection,mounted in Aquitex and preserved on a flat microscope slide with the coverslip sealedwith Artmatic clear nail polish.Tigriopus ca4fornieus individuals were collected concurrently from splashpoolpopulations in Barkley Sound and examined for abundance and maximum length of: 1)eggs (including brood size); 2) nauplii (stages N-I to N-VI inclusive); 3) copepodites(stages C-I to C-IV); and 4) mature adults (stages C-IV to C-VI, including gravidfemales). Samples were drawn randomly in July and October of 1994 and January andMay of 1995 from pools retaining the above temperature and salinity ranges over at leastthree consecutive days. All individuals were either narcotized in 10% carbonated water(Gannon and Gannon, 1975) to facilitate vital examination with a dissecting microscope,or sacrificed for detailed examination using a compound microscope at highermagnification, usually within 12 h of collection.RESULTSThe results of Tigriopus californicus life-history stage development and durationare summarized in Table 4.1. Eggs begin as green spheres, becoming. red or dark orangewith maturation as the eye develops. Egg sacs are carried in a single brood sac by thegravid female, and eggs usually hatch within 24 h of deposition or removal from thefemale (slowed by 12 to 24 h in the solution at 10 - 15°C, see Table 4.1). Theseobservations coincide with the observations ofKahan et al. (1988) for T japonicus andHuizinga (1971) for T calfornicus; but is much more rapid than either the 2.4 days (at23°C) to 8.2 days (at 10°C) noted by Egloff (1966) for T ca4fornicus.Chapter 4: Development, Size, and Feeding 84TABLE 4.1. Development of Tigriopus cahfornicus in laboratory culture. Summer denotescultures at 18 - 20°C, 30 -32%o salinity; winier denotes cultures at 10 - 15°C; 20 - 25%osalinity. Supporting media for all treatments was 1.5 L of natural pool water, replenishedwith distilled, de-ionized water and inoculated with fish flakes or mixed bacterial culture.Parentheses indicate number of specimens observed of each life-history stage. Description ofmorphology sensu Coull (1982).Life-HistoryStageNauplius stagesN-I summer(32) winterN-TI summer(28) winterN-HI summer(26) winterN-TV summer(22) winterN-V summer(25) winterN-VT summer(25) winterCopepodite StagesC-I summer(18) winterC-TI summer(15) winterC-ITT summer(19) winter(20) summerwinter 1-2C-VT summer 28+(45) winter 28+(40) summer 28+winter 28+Urosome develops anteriorallyFirst setae on proto-urosomeBegins (observable) feeding andswimmingEnlargement of body;Lateral prosome setae bifurcateUrosome segmentation evidentUrosome segmentation advancesP1, P2 appendages appear5 somites + caudal rami;P3 appendages appear6 somites + caudal rami;P1 to P3 appendages complete7 body somites + caudal rami;P1 to P4 appendages complete;PS appendages appear8 somites + caudal ramiSexual dimorphism occurs;Males develop larger Alantennules and larger body size;Female P1 may be larger, moredeveloped, female PS appendagefused, modified for egg clutch;11 somites + caudal ramiStage Days BodyDuration After Egg Diameter(Days) Deposition (gm)egg summer 1 < 1 50 - 80 Green color becomes red due to(56) winter 2 1-2 50 - 90 microflora and eye developmentDevelopment11112-3311112-332-33-42-33.-42-33-42-33-411-22334677889101213161520182420282130213030+30+30+30+40 - 8040 - 8050 - 10050 - 100100 - 150100 - 150150-200150-200200 - 300200 - 300200 - 300200 - 300430-460400 - 420520 - 550500 - 530650 - 700630-660740 - 760730-7601100 (males)10001000 (females)880 - 10001400 (males)13001100 (females)1000- 1100C-TV(15)C-V(23)summerwintersummer‘winterFemale C-VT molt may not occurwithout fertilization of C-VChapter 4: Development, Size, and Feeding 85Clutch size was seen to be highly variable in all seasons, particularly in fieldpopulations (Figure 4.1). The observed range in clutch size was 12 to 56 eggs. Clutchsize for laboratory cultures (52 individuals) was 20 ± 4.2 eggs (mean ± SE.) at10 - 15°C and 26 ± 8.1 eggs at 18 - 20°C (mean values rounded to the nearest wholeindividual). Gravid females from field populations (an additional 87 individuals) had amean clutch size of 23 ± 6.5 eggs at 10 - 15°C, and 37 ± 10.2 eggs clutch4 in poolssampled in July and August (61 individuals). Non-viable progeny accounted for 10±9.1% of all eggs (n = 1092) at the lower temperature/salinity and 10.8 ± 7.8% (n = 1837)at the higher temperatures and salinity.As indicated in Table 4.1, development of T. cahfornicus nauplius stages ismarked principally by the behavior exhibited, a six-fold increase in size (diameter), and theonset of segmentation of the urosome. The nauplii are nearly transparent except for theeye spot at the N-VI stage. Feeding on particulate matter is not observed prior to the NIII stage, although absorption of dissolved materials through the cuticle or feeding oninternal reserves may be possible. Self-directed swimming (auto-locomotion under non-turbulent conditions) is also not observed prior to the N-HI stage, which may enhance thesusceptibility of the organism to cannibalism or predation during its early life-history.There was also no appreciable difference in the size and morphological development ofnauplii under “summer” versus “winter” culture conditions, however the net developmentof T. cahfornicus from egg through stage N-VT is slowed by 2 days overall at the lowertemperature/salinity range. The net size of the organism at the N-VI stage remainedwithin the 200 to 300 lIm size range under both rearing regimes.Development of the copepodite stages C-I through C-TV is externally evident bysegmentation of the metasome and urosome, with an increase in body length of 50 to 100p.m and the appearance of an additional pair of swimming legs (appendages to P5) ateach molt. Copepodite development was also observed to be slower at the lowertemperatures, adding approximately 1 day to each interval between molts for a netChapter 4: Development, Size, and Feeding 86difference in development time of more than a week from egg to maturation, the C-VIstage. The observations additionally suggest that the stage C-V female may not molt intothe C-VI stage unless it is fertilized by the male, contrary to the observations of Harris(1973) and Burton (1985). Further, C-V females are usually clasped soon after they molt,and riding may be inhibited if the male cannot clasp the female or implant thespermatophore after the cuticle has hardened. Only trial-and-error attempts at couplingby the male or a chemical secretion associated with the molt may indicate receptivity ofthe female to clasping. Overall body length of all life-history stages was seen to be morevariable at the lower temperature range and in field populations, but did not differsubstantively from the size ranges observed in culture (Figures 4.2 and 4.3). Wheredifferences in length were noted, cultured organisms were generally shorter in length thanthe field specimens, an artifact that may indicate differential food availability, or variationin the overall body size or volume not indicated by a single linear axis.From the description of Coull (1982), TigrEopus ca4fornicus exhibits a fusiformcompressed body form at maturity; sexual dimorphism occurs at the C-IV stage, when theorganism can be sexed by a larger, geniculate A1 antennule in the male, and a moreintricate P5 swimming appendage in the female, where the basis and endopodite are fusedand may protect or serve as an attachment point for egg sacs. The P1 appendage mayalso be larger and more setated in the mature female. Characteristic of the generalizedharpacticoid plan (Coull, 1982), articulation with the urosome occurring between the fifthand sixth body segments (somites) and the fully-developed A1 (antennules) are biramousand eight segments in length. The prosome is broader than the urosome and consists ofthe cephalo-thorax (the three fused, anterior-most somites) and the metasome (the nexttwo body segments, which are generally smaller and restricted in their articulation). Afurther six somites comprise the urosome in advance of the caudal rami, and the rami maybe apparent as early as the C-I stage.dD00rChapter 4: Development, Size, andFeeding 87Figure 4.1. Seasonal Brood Size of Tigriopus cahfori*us50454035302520151050January April May June JulyMonth of SamplingAugust OctoberFIGURE 4.1. Seasonal brood size in TigrEopus cahfornicus. Mean brood size for 52gravid females samples from laboratory culture and 87 additional females collected fromfield populations during the months indicated. Pools were selected with temperature andsalinity parameters representative of seasonal mean. Note that data are only available forfour months for laboratory cultures, compared to seven months for pool samples. Errorbars indicate ± I SE.rl)I602Chapter 4: Development, Size, and Feeding 88Figure 4.2. Tigriopus californicus Overall Body Lengthat 18 -20 Degrees Celsius; 100% Sea WaterIn PoolIn Culture1600-1400120010008004002000-Egg N-Ill stageLife-History StageFIGuRE 4.2. Overall body length of TigrEopus calfornicus at 18 - 20°C; 100% sea water(30 - 32%o salinity). For illustration, only the median nauplius (N-Ill) and copepodite (CIII) stages are presented. Error bars indicate ± I S.E. of the mean values for n 150eggs and n = 50 individuals of each subsequent stage.Chapter 4: Development, Size, and Feeding 890IIEgg N-Ill stage C-Ill stageLife-History StageFigure 4.3. Tigriopus ca1fornicus Overall Body Lengthat 10 - 15 degrees Celsius; 65% Sea Water1600-1400Tn Pool•Jn Culture10008002000Female MaleFIGURE 4.3. Overall body length of Tigriopus californicus at 10 - 15°C; 65% sea water(20- 25%o salinity). For illustration, only the median nauplius (N-ffl) and copepodite (CIII) stages are presented. Error bars indicate ± 1 S.E. of the mean values for n = 150eggs and n = 50 individuals of each subsequent stage.Chapter 4: Development, Size, and Feeding 90From Table 4.1 and Figures 4.2 and 4.3, the net size of the mature individualsdiffered little between the two temperature/salinity ranges in laboratory culture. Culturespecimens also did not differ significantly from field specimens collected concurrentlyduring the summer and winter (Student’s t-test at a= 0.05, P <0.20).DIscussIoNCulture Maintenance: Huizinga (1971) maintained T. californicus in 20 cmfinger bowls, in natural sea water, for one week. As nutritive media, 150 mg of blendedPurina Rat Chow® was added every four to seven days; the fluid medium was diluted to1300 mL with prepared sea water, covered and left at room temperature. Evaporatedwater was replaced by distilled water, while cultures were split every two to three weeksinto sub-samples containing approximately 500 adults and topped up to 1300 mL withartificial sea water. In marked contrast to Huizinga’s custodial method, Fraser (1935)reports the retention of T. fulvus in a sealed jar of natural pooi water for more than a year,and observed activity of the organism days to months after the vessel was re-opened.Considering the generally high surface-area-to-volume ratio of the copepod’snatural habitat, retaining a large interface with the air is essential to provide adequateoxygenation to cultures, particularly those with dense populations. Interruption of thisinterface, as by oil contamination, has been shown to be deleterious to T. cailfornicuscultures (Kontogiannis and Barnett, 1973). Using 2 L Erlenmeyer flasks, coveredloosely with a watch glass to prevent evaporation, and replenished gradually with filterednatural sea water at Ca. 32% salinity has yielded the most success for the cultures usedfor the current study. Such an arrangement provides a generous air/sea water interfacewhile reducing the evaporative loss and occupying a minimum of shelf or bench space.The use of DDW or SOW may be desirable in some applications (including the currentone) to maintain the physico-chemical constancy of the solution, however I have not hadChapter 4: Development, Size, and Feeding 91success in supporting T. californicus cultures for any duration using these more ‘sterile’solutions. Cultures have frequently been lost in media that has become too clean (i.e.,lacking appreciable microflora).From the above results, T. cahfornicus cultures seem to sustain themselvesequally well at room temperature or under refrigeration and a linear correlation betweenrearing temperature and body length or brood size is not apparent. Takano (1971) foundsunlight and storage temperatures in excess of 28°C to be harmful for cultures of T.japonicus, and suggests aeration and/or changing the water frequently under theseconditions. Huizinga (1971) noted that high ambient light levels caused a filamentous redalga to form that was deleterious to T. californicus. I have observed no ill effects oncultures retained under standard fluorescent lighting under either constant light or a 12:12or 16:8 light:dark cycle.Feeding: Published accounts of nutritive media for Tigriopus include unicellularalgae, dried shrimp powder, mulberry leaves, rat food, and bacteria (Table 5.2). Invirtually all examples, the “food” provided is not natural to the copepod’s habitat, earningthe organism the (likely erroneous) designation of a “generalist feeder.” Tigriopuscalifornicus wifi feed on any number of items, from commercial fish food to mixedbacterial culture to multigrain bread - any living substance which promotes the formationof bacteria (cf. Robinson, 1957; Harding, 1974). For this reason, cultures should beprovided with nucleating materials that promote bacterial growth, kept slightly cloudy anddecidedly non-sterile without allowing so much bacterial growth or accumulation ofnitrogenous wastes that conditions become inhospitable. These observations concur withHuizinga (1971), who noted that T. californicus cultures are tolerant to overfeeding andputrescence.Gilat (1967) referred to T. brevicornis as a filter-feeder, without any apparentresults to support this claim (noted by Hicks and Coull, 1983). Morris et al. (1980, p.632) state that T. californicus “can filter feed to some extent, like most free-livingChapter 4: Development, Size, and Feeding 92TABLE 4.2. Food items used for culture of Tigriopus congeners. Additional referencesfor the use of food items for Tigriopus cultures are tabulated in the review of Hicks andCoull (1983, p. 138).Study Tigriopus species Food Provided (as cited)Fraser, 1936b T. fulvus Nitzschia closteriumTakeda, 1939 T. japonicus dried, powdered shrimpHanaoka, 1940 T. japonicus diatomsProvasoli et al., 1959 T. japonicus Rhodomonas + IsochrysisPlatyrnonas + bacteriaChroOmonas + vitaminsLear and Oppenheimer, 1962 T. californicus Platymonas (—Tefraselmis)Vacquier and Belser, 1965 T californicus Platymonas (=Tetraselmis)Comita and Comita, 1966 T. brevicornis Phaeodactylum triconutumEgloff, 1966 T. californicus Platymonas (=Tetraselmis)Shiraishi, 1966 T. japonicus bacteria-free algaeKoga, 1970 T. japonicus Chiorella, beer yeast, processedtrout foodHuizinga, 1971 7’. cahfornicus Purina Rat Chow,Chiorococcum, Oscillatoria,Oxyrrhis, EuplotesTakano, 1971 T. japonicus Cyclotella, Phaeodactylum,NitzschiaHarris, 1973 T. brevicornis centrifuged natural sea water(35%o,500p.gNfL)Rothbard, 1976 T. japonicus Ulva petrusaWatanabe et at, 1978 7’ (/aponicus) bake?s yeast, soy cakeO’Brien et a!., 1980 7’ californicus fish foodLee and flu, 1981 T. japonicus ChiamydomonasVilela, 1984 T. brevicornis Plalymonas (=Tefraselmis),Nannochioris, fish flakes,vegetablesKahan et at., 1988 T. japonicus wheat germ, natural algae.Lee and Taga, 1988 T. japonicus Acinetobacter bacteriaLazzaretto et al., 1990 T. californicus boiled wheat, unicellular algaeT. fulvusT. brevicornisPavilion et al., 1992 T. brevicornis Tetraselmis cordiformisPalmer et al., 1993 T. californicus Isochrysis, fish food.Chapter 4. Development, Size, and Feeding 93copepods, but is primarily a browser [oni algae and detritus.” The description of filter-feeding is used again by Huizinga (1971) and Harris (1973), although the latter referencediscusses filtration only in regard to removal of phytoplankton cells. In comparing thefeeding appendages of T. cahfornicus with those ofAcartia tonsa, Egloff (1966) assertsthat T. calfornicus cannot be a filter feeder, since the plumose setae of its mandibularpaips and first maxillae are poorly designed for generating feeding currents or strainingwater. From Egloff (1966, p. 11) the coxa ofT calfornicus has a strong cutting edge,with a small basipodite and a long endopodite; a similar clarification is made by Ito(1970), and Sullivan and Bisalputra (1980) also suggested that the setae of the mandiblesof T cahjornicus fhnction in mastication, rather than filtration. Syvitski and Lewis(1980) describe T ca4fornicus feeding on particles 0.5 to 50 urn in diameter, some 20times smaller than previously noted for the organism, however at the low Reynold’snumbers typically experienced by these microcrustaceans, setae on feeding appendagesmay indeed operate more akin to paddles than filtering sieves. In stock culturepreparations, natural sea water is typically filtered at 0.45, which would prevent thepassage of most particles of this size range into the stock cultures. Fraser (1 936b) and ItO(1970) provide more appropriate descriptions of Tigriopus feeding, the latter studydescribing surface browsing as the means of feeding in T japonicus. From the excellentreview of Hicks and Coull (1983), food acquisition in Tigriopus species might bestcompare to the prey-crusher variety of feeding described in Marcotte (1977).A census of the gut contents of T cahfornicus by Egloff (1966) revealed thedietary items to be (in order of abundance and not further specified): 1) diatoms; 2) greenand cyanobacteria; 3) filamentous green algae; and 4) nauplii and copepoditeexoskeletons. Huizinga’s (1971) census of gut contents includes: 1) the green algaChiorococcum; 2) the cyanobacterium Oscillatoria; 3) the dinophyte Oxyrrhis; and 4) theprotozoan Euplotes, with each having been cultured on the blended commercial rat foodprovided as a nutritive media.Chapter 4: Development, Size, and Feeding 94With any census of gut contents, the designation of “preferred” food must betempered with considerations of relative abundance or possibly noxious taste of alternatedietary items. Although T cahfornicus is capable of cannibalism, only diatoms andbacteria alone may be fed upon preferentially, while the remaining materials are ingestedby happenstance. The amount of detritus, macroalgae, and other copepods that areconsumed will therefore correspond with the amount of sediment or detrital materialpresent, and the density of the copepod population. Egloff(1966) proposes cognitivepredation by female T. caflfornicus on its own nauplii, and Lazzaretto and Salvato (1992)discuss cannibalism in T. fulvus at higher population densities (in excess of 20 individualsIn contrast to several feeding studies that suggest mixed algae is the staple foodresource of harpacticoids (e.g., Lear and Oppenheimer, 1962; Shiraishi, 1966; Battaglia,1970; Vilela, 1984), marine bacteria alone may provide a sufficient food resource forTigriopus species in situ, in accordance with the laboratory results of Provasoli et al(1959); Gilat (1967); Hanaoka (1973); Itoh (1973); Rieper (1978; 1982) and Carli et al.(1993). Lee and Taga (1988) found iO6 cells• mL1 ofAcinetobacter spp. to be ideal forthe development of all life-history stages of T. japonicus, a bacterial concentrationrepresentative of bacteria levels in the splashpools for that study (see General Discussion).Alternately, Itoh (1973) provided an estimate of 0.31 - 1.02 ig dry bacteria day-1 for Tjaponicus, while Rieper (1978) provided a more general estimate for harpacticoids of2.06 - 7.07 tg dry bacteria day or 1 - 3.5 igC copepod1 day. From Khalov andYerokhin (1971) and Carli et al. (1993), the bacteria found naturally in pools and inassociation with the cuticle of the copepods may also assist in the uptake of dissolvedorganic matter through the cuticle (but see Anderson and Stephens, 1969).Development ofLfe-History Stages: Tigriopus ca4fornicus apparently exhibitsthe “typical” harpacticoid development (Hicks and Coull, 1983), molting through sixnauplius and six copepodite stages (including the adult) after hatching from the egg.Chapter 4: Development, Size, and Feeding 95Although Harris (1973) identifies six copepodite stages for. T brevicornis, Huizinga(1971) identifies only four naupliar and four copepodite stages plus the adult stage for T.californicus. Sexual dimorphism based externally on the A1 antennule (males) andflattened P5 baseoendopodite (females) agrees with the distinction provided by Monk(1941), Egloff (1966), and the observations of Burton (1985).Egloff (1966) also suggested that body size and coloration may be used todifferentiate the sexes of T. cahfornicus, however these characters are likely dependenton the diet and thermaL’haline history of the culture. In the advanced life-history stages(copepodites and mature adults), the characteristic orange or reddish coloration of T.calforiîicus has been observed to coincide with the florescence of microflora in the gut(cf Rieper, 1982). Though the organism does not begin feeding until the N-ill stage, itmay be possible that some of the microflora is transmuted to the egg sacs as they ripen bythe female.While I have observed very little variation or net difference in final body lengthbetween summer and winter conditions, changes in osmotic conditions may produceswelling or shrinkage of the copepod’s cuticle, thus changing the body’s size or volume.Preparation techniques may also promote shrinkage or distention of specimens, and so atechnique which considers changes in the overall body size or body volume (e.g., Wulif,1972) would be more appropriate than recording length parameters if a more detaileddetermination of somatic growth is intended.The use of a range of 2 to 5°C for each culture is justified in being morerepresentative of microscale changes in pool temperatures in situ, rather than the typicalmethod of holding this variable constant. The thermal or saline ‘history of the pools (i.e.,conditions prior to the time of sampling which may have been greatly dissimilar to thethose used for culture), if present, appear to have had little effect on the net size or rate ofdevelopment of the cultures ultimately produced. While closely representative of theseasonal conditions in Barkley Sound, the range of temperatures used in the current studyChapter 4: Development, Size, and Feeding 96to differentiate summer and winter cultures may not have been distinct enough to promotedifferential growth rates or body length.An overall slowing of development was observed at the lower temperatures(9 days overall at 10 - 15°C), but did not record increased incidence of egg mortality witheither temperature or culture source. Egloff (1966) noted enhanced egg mortality at lessthan 10°C and greater than 25°C, which are potential but infrequent temperature extremesin our field sites. The total development time (egg to adult) for T cahfornicus calculatedby Huizinga (1971) is 18 - 21 days at 23°C; Egloff (1966) reported 16.5 days at 23°C and27.5 days at 15°C. With no further information on salinity and food conditions of culturein Egloffs study, I can claim only comparable results with respect to overall generationtime.Despite the relative consistency of egg hatching time, the determination of broodsize and the potential mechanism for hatching are yet unclear. Provasoli et al. (1959)suggested that hatching in T californicus and T japonicus may be induced by light;Kahan et al. (1988) proposed the transmission of chemical messengers from the female inT japonicus. The potential for differential egg viability or sex ratio from natural egg sacdeposit relative to ‘forced hatching has not, to my knowledge, been studied. Egg sacswill usually hatch within 24 hours when deposited from live females, Sacs are droppedfrom sacrificed individuals almost immediately, with the eggs again hatching within 24hours (Vacquier and Belser, 1965; Kahan et al, 1988). Egloff(1966) described a methodfor egg examination by dissolving the sac in a solution of 20 - 30% Chlorox bleach(sodium hypochiorite), but in practice, any solution applied to the sac will likely be carriedto the eggs and may affect their viability; I have found that the brood sac is best removedfrom the gravid female using micro-forceps. To avoid damaging the egg sacs, Kahan etal. (1988) sacrificed adult female T japonicus by mechanical injury to the head; theseauthors also describe a method for specimen preparation for scanning electronmicroscopy (SEM) analyses. Egloffs (1966) results for the time required for eggChapter 4: Development, Size, and Feeding 97hatching (2.4 to 8.2 days) are .quite different from the current results, which may either bedue to 1) the means of separating the egg sac; or 2) Egloff presenting his data as the totaltime from insemination, not the time of egg sac formation.The duration of each N-stage is approximately one day, with the exception of theN-Ill and N-Vl stages, which are of slightly longer duration. The current study usedequal initial numbers of nauplii for both “winter” and “summer” cultures, however Leeand Hu (1981) achieved their highest mean number ofT. japonicus nauplii (36) at asalinity of 30. 7%o. Upon molting to copepodite stages, the duration for each stageincreases to two to three days, and often three to four days at 10 - 15°C. From Table 5.1,the formation of an additional somite and the onset of an additional pair of swimmingappendages is indicated for stages C-I to C-HI, with sexual dimorphism occurring at theC-IV stage. The range of body lengths observed in the current study agrees generallywith the sizes provided in Ward and Whipple (1959): 0.94 - 1.1 mm for males, 0.96 - 1.4mm for females, although I find the C-VI males to most usually have a longer (andgenerally larger) prosome and urosome than the female Longevity of the C-VT adults inculture has not been accurately established, but appears to depend principally on thequality of the support media, notably the amount of bacteria present and the avoidance ofaccumulated wastes. Adults isolated from my stock cultures have survived for more than30 days, and Vittor (1971) estimates a lifespan of 100 to 140 days for T ca4fornicus at20°C.Brood Size: The mean brood size obtained within either temperature range (20 ±4.2 eggs at 10 - 15°C; 26 ± 8.1 eggs at 18 - 20°C) is considerably lower than results ofComita and Comita (1966), who derive a first brood average of 32 at 11 °C in T.brevicornis. Harris (1973) records a brood size of 27.5 eggs• clutch at 10°C and 28.3eggs clutch at 20°C for the same species, though a change in brood size with rearingtemperature is not indicated. For T ca4fornicus, the current results from cultureapproximate more closely mean value of 18 eggs• clutch-1 provided by Huizinga (1971)Chapter 4: Development, Size, and Feeding 98and the median value of 20 eggs clutch1 reported by Vittor (1971, p. 40) for T.cahfornicus in “100% sea water” at 20°C. While his observed brood sizes were alsohighly variable, Vittor’s (1971) results do not indicate that brood size is enhanced withhigher food abundance; increased energy reserves for reproduction may instead beinvested in the production of a greater number of brood sacs. Egloff(1966) found in situbroods for T cahjornicus to range from 15 to 140 eggs with a mean of 46 and mode of32, which again might be attributed to differences in food availability, or a difference inthe brood sacs enumerated. Comita and Comita (1966) observe an increase in clutch sizefrom the first through the third broods; while I removed the first observed egg sac fromlaboratory culture females, it could not be determined which brood was removed fromgravid females sampled from poois.Mating: Burton (1985) sufficiently summarized the mating system inT calfornicus, and notes that males may clasp C-Il to C-V females for up to a weekbefore the female’s terminal molt. Females are noted to mate only once, as there is noevidence of sperm displacement, while males were observed to inseminate an average of2.5 ± 0.8 females in 72 hours (Burton, 1985). Given a lifespan of 50 to 80 days for theadult (also from Vittor, 1971), it is conceivable that some 300 progeny could be producedfrom a single insemination (calculations by Burton, 1985), which compares to the total of301 eggs produced from a single T brevicornis female, calculated by Harris (1973).In many samples, T cahfornicus is seen to be almost entirely clasped into matingpairs. Clasping for a duration longer than is needed for sperm transfer is not uncommonin crustaceans (e.g., Manning, 1975; Shuster, 1981; Thornhill and Alcock, 1983), andBurton (1985) noted that, since clasping is done with the antennae, feeding may stilloccur in the male and the female while in the riding position. There may be a tremendouscost associated with long-term clasping, but the ability of males to mate several times,while the females mate only once, will produce a low frequency of available females andfinding the most mature female will consequently reduce the amount of time invested inChapter 4: Development, Size, and Feeding 99mating. Mate guarding is frequently noted to occur in situations where there is a paucityof potential mates and is supported by observations of two or more males attempting toclasp a single female. The observation that males clasp ‘females’ as early as the C-Il stage,suggests (though does not confirm) that male copepods can distinguish females before thesexually dimorphic C-TV stage. The cost to the male then becomes not the production ofsperm, but the reproduction missed while remaining clasped to an unreceptive female untilthe C-V molt. It is also not known how often males may clasp mistakenly an immaturecopepodite that develops into another male or whether clasping affects the sexdetermination.Bozic (1960) suggested that fertilization of the female must occur immediatelyafter the terminal molt, but Egloff (1966) and Burton (1985) revise this, and observe thatfertilization may occur any time after the terminal molt. Harris (1973) observed a delay ofsix days between the female molt from the C-V stage to the adult, and the onset of eggproduction in T. brevicornis. Given the above conditions, the availability of mature,unfertilized females is likely rare, and Burton (1985) noted that if fertilization occurs priorto the terminal molt, non-viable eggs are produced. My observations as well as those ofM. Spaeth (pers comm.) suggest that the terminal, C-V to C-VT molt may not occur in T.calfornicus females unless fertilization occurs. This observation, as well as furtherclarification of the effect of differential temperature and salinity on body volume and theproduction of successive broods is here proposed as an avenue for future study.CONCLUSIONSTigriopus californicus was observed to develop through the “typical” harpacticoidlife-history of six naupliar and six copepodite stages, which somewhat revises and clarifiesearlier descriptions, including that of Huizinga (1971). Development of nauplii (stagesN-I through N-VT) occurred in 10 days under ‘summer’ conditions and 12 days under‘winter’ conditions; copepodite development (stages C-I through C-VT) was similarlyChapter 4: Development, Size, andFeeding 100delayed from 11 to 18 days at the lower temperature/salinity. Total generation time (eggto adult) was 21 days for the higher temperature/salinity values, and 30 days at the lowervalues, although no net difference in body length was observed. Clutch size was 20±4.2eggs (mean± SE.) at 10- 15°C and 26 ± 8.1 eggs at 18- 20°C. for gravid females inculture; field specimens had a mean clutch size of 23 ± 2.5 eggs at 10 - 15°C, increasingto 37±4.2 eggs• c1utc1r during the summer months (July and August), and possiblyindicative of the quality and supply of food available in situ. Non-viable progenyaccounted for 10± 8.1% and 10.8 ±7.8% of all eggs under ‘summe? and ‘winte?conditions, respectively.CHAPTER 5: SEAsONAL ABUNDANCE AND POPULATION FLux OF TIGRIOPUSCALIFORW1CUS IN BARKLEY SOUNDINTRODUCTION“Chaos often breeds life, when order breeds habit.”— HENRY ADAMS (1907)Sampling considerations endemic to the study of oceanic or fresh water planktonpopulations are equally applicable to the study of microcrustacea in isolated coastal areassuch as estuaries, salt marshes, seagrass beds and coastal pools. Such generalconsiderations include: spatial heterogeneity (Barnes, 1949; Wiebe, 1970; Smith et al.,1976; Mackas et al., 1980; Beers et al., 1981), organism response and behavior (Forwardand Cronin, 1980; Harris and Morgan, 1986; Lampert, 1989; Hough and Naylor, 1992;Haney, 1993; Lampert, 1993), atmospheric and hydrological effects (Brooks, 1979;Calaban and Makarewicz, 1982; Kimmerer and McKinnon, 1987), sampling scheme andsampler design (Beers et al., 1967; Omori and Hamner, 1983; reviewed in Powlik et al.,1991). A number of studies have utilized the natural abundance, small size, andcomparatively short generation time of copepod populations within these smaller anddiscrete habitats to model or estimate processes for meiofaunal populations, including:distribution and migration, life-history strategies, feeding and excretion, production,growth, aging, and decay (Egloff, 1966; Vittor, 1971; Heip and Smol, 1976; Feller, 1980;Palmer, 1980; Thistle, 1980; Kimmerer and McKinnon, 1987; PaffenhOfer and Stearns,1988; Kern, 1990; White and Roman, 1992; Dybdahl, 1994).Egloff (1966) suggested that results on the population structure, age, sex ratio,and density-depended behaviors observed in splashpool copepoda may be extended in101Chapter 5: Abundance and Population Flux 102application to pelagic plankton assemblages. However, the designation of true ‘replicate&among littoral pools is made more difficult by localized differences in tidal elevation,exposure to wave wash, pool water properties, resident meiofauna, vegetation and shoredebris (Metaxas and Scheibling, 1993). Moreover, the smaller, isolated volume of coastalpools enhances the effects of oxygen production, changes in pH, bacterial activity ondetrital material or accumulation of chemical exudates, toxins or pollutants, andpotentially noxious wastes. Even minor changes in any of these parameters may have asubstantive effect on the entire volume of the pool, and the action of a single wave orstorm event may potentially replenish or decimate the entire population of a pool (Vittor,1971; Dethier, 1980, and the preceding chapters) Battaglia (1970) additionally cautionedthat any models or population studies derived from such a specialized, highly variablehabitat will not easily translate to speculation about less specialized or extreme habitats.As isolated (or semi-isolated) vessels for mensurative or manipulative studies ofaquatic ecology in situ, splashpools and fresh water rockpools are without comparison fortheir ease of access, demarcation of the water mass to be sampled, and provision of astable work platform. These benefits are counter-balanced by other factors thatcomparatively affect smaller water masses to a much greater extent, including: heating bysolar radiation, cooling by wind, evaporation, and dilution by precipitation (Morris andTaylor, 1983; Thiéry et al., 1995), eutrophication produced from stagnation, the depositof debris, or nitrification from animal excreta (Ganning and Wulif, 1969), habitatcomplexity (Hicks, 1980; Coull and Wells, 1983), or the enhanced number and diversityof competing, grazing or predating organisms (Fraser, 1936; Barnes, 1949; Guberlet,1956; Lubchenko, 1978; Kozioff, 1983: Lampert, 1993).The descriptions of Tigriopus development in laboratory culture far exceed thosestudies addressing population density, growth, and extinction of field populations ofsplashpool copepods (see previous chapters). Population are reported, usuallyonly as individuals mL1 or L, with little further detail provided. As with most ofChapter 5. Abundance and Population Flux 103ecology, early studies of Tigriopus field populations (e.g., Igarashi, 1959, 1960) wereprimarily qualitative in their observation, or provided only anecdotal accounts of fieldconditions (but see Fraser, 1936 a, 1 936b). Later studies sought to relate the response ofTigriopus populations - usually in the laboratory- to broader ecological paradigms of theday, including the expression of sex ratio (Vacquier and Belser, 1965; Egloff, 1966),population structure and strategy for growth (Vittor, 1971; Harris, 1973), or the influenceofpredation on intertidal distribution (Dethier, 1980). More recently, Dybdahi (1994,1995) addresses the extinction of T. cahfornicus populations as it pertains to foundereffects and re-colonization, but bases his calculations on several inapplicable assumptions.A reliable, predictive estimate for the growth and decline of Tigriopus field populationshas not been published.The foregoing studies and discussion in this thesis have sought to provideparameters (or ranges of parameters) that are descriptive of the seasonal conditions foundin the supralittoral splashpool of southeastern Barkley Sound. For the most part, thesedata were collected during short (one-to-two week) sampling intervals, providing a‘snapshot’ of extant conditions throughout the year (Figure B 1; Appendix C). However,given the ephemeral and highly variable physical and chemical conditions present in thesepools, it would be instructive to determine how representative these observations are ofthe conditions experienced by T calfornicus field populations for the remainder of theyear.The intent of the current chapter is to present data on the seasonal density and agestructure of T. californicus populations in Barkley Sound, considering not only the natureof the habitat itself (Chapter 1), but more significantly, the processes occurring withininhabited pools, and even within the organism itself (Chapters 2, 3, and 4). Comparingthe ‘predicted’ results for population florescence or extinction to conditions observedduring the sampling intervals may then provide a measure of how representative orpredictive these observations are for determining the dynamics of field populations.ChapterS: Abundance and Population Flux 104Notes on sampling considerations for splashpools as well as the benefits and limitations ofcertain types of sampling gear will also be discussed.MATERIALS AND METHODSField Sampling. Splashpools containing Tigriopus californicus were surveyedseasonally from field sites in southeastern Barkley Sound (see Chapter 1 for field sitelocation and details of survey methods). For sampling copepods, each pool was dividedinto a numerically-assigned sextet, and a six-sided die was rolled to allow a randomized,triplicate sample. Copepods were then collected using a 30 mL graduated pipette drawnalong the pooi bottom at these randomly-assigned positions. Scouring, pumping, or moreinvolved means of sampling the poois were avoided, as this may have produced anundesirable level of disturbance.Pipette samples were stirred into a homogenous solution and split into two equalfractions: One fraction was narcotized in situ using 10% carbonated water (Gannon andGannon, 1975) and enumerated to (approximate) life-history stage using a fieldmicroscope or jeweler’s glass; the second fraction was returned to the laboratory,sacrificed, and identified to life-history stage under higher magnification (see Chapter 4).In those pools where T. californicus was found, copepods were narcotized andcounted in triplicate for: 1) male-to-female ratio; 2) ovigerous females, including 3) clutchsize; 4) immature copepodites; and 5) nauplii present, averaged where repeated countsdiffered. Pools were considered lacking T. californicus if three successive pipettescontained no copepods.In contrast to the usual sampling regime for the field sites (wherein each pool wassampled every two to three days during the sampling interval), pools selected forevaluating population density and flux were sampled each day for at least one week, orlonger, depending on time availability. It was not possible in the time available to censusall 85 tagged poois in this manner, hence a sub-sample of pools was selected by stratifiedrandom sampling from each field site in Figure 1.1 (see Results for n values used).Chapter 5: Abundance and Population Flux 105Estimating Population Size: The model provided here permits growth to theobserved population maxima of 2,000 individuals L in winter and 20,000 individualsL1 in summer. From the assumed founding population of 10 individuals (Chapter 3),two individuals (20%) will be mature females, either carrying eggs, previouslyinseminated, or inseminated within 72 hours (assumed) of introduction; 3 will be maturemales; and the remaining 5 individuals will be immature copepodites or nauplii, maturingin the first or second week following introduction. From Chapter 4, an average broodsize of 23 eggs (winter) and 37 eggs (summer) is here assumed, with an average viabilityof 90%. Based on the results of the current chapter, I use a sex ratio of 1.46(male:female) in winter and 1.36 in summer.Maximum Population Size: I suggest that values of 2000 and 20,000 individuals• L1 are representative of commonly observed maxima in winter and summer,respectively, however on at least one occasion I found natural concentrations of T.ca4fornicus in excess of 200,000 adults per liter, as calculated from a homogenous, 1/16-split sample (see Results). In application, these maxima will probably not be reached overthe period of time estimates.Population Growth: The generation time (egg to adult) of 30 days under wintertemperatures and salinity, and 21 days under summer temperatures and salinity is assumed(Chapter 4). Other assumptions used in the calculation of Tables 5.3 and 5.4 are: 1)10%mortality of nauplii molting to copepodites and a further 10 % mortality for copepoditesmolting from copepodites to mature adults; 2) a rate of development commensurate withthe results of Chapter 5 at both summer and winter temperatures; 3) an adult longevity ofat least 5 weeks; and 4) no population decimation due to biotic or abiotic factors.Frequency ofExtinction: For the current analysis, an ‘extinction’ was tallied eachtime a previously inhabited pool was found to be without T ca4fornicus duringsubsequent sampling intervals; the reverse condition was taken to indicate ‘colonization,’Estimating Population Flux: The results and discussion of preceding chaptersChapterS: Abundance and Population Flux 106provide the parameters of pooi condition, seasonal population structure of Tigriopuscalifornicus, and frequency of extinction or florescence. Where applicable, morepertinent (by season) or illustrative (by result) values from previous studies have beenused (Table 3.1). For the purposes of estimating T. caljfornicus population dynamics, thefollowing assumptions will be applied to the ‘model’ of population growth and decline:1. that the initial (founding) population is eight to 10 individuals, of various life-historystages, which is a ‘typical’ colonizing population from the results of Vittor (1971)and Dybdahl (1994). Following the results of Chapter 3, 50% of these colonizerswill be mature adults (including gravid females), with copepodites and naupliicomprising the remaining 50% and maturing within one to two weeks;2. that the male-to-female ratio initially approximates 1.47 in winter and 1.36 insummer (from the above results). The ‘expected’ ratio of 1:1 is rarely observed innatural populations (due to differential growth, mortality, or gender-specificselection by environmental conditions), and will vary according to season andrearing conditions;3. that clutch size, time of hatching, and life-history stage development occurs at thesame rate as observed in laboratory culture (Chapter 4) and is therefore estimatedprincipally from seasonal temperature and salinity. While food type and quantityare also an essential consideration, this has not been included in the currentcalculations. Data on the specific food type and abundance available tosplashpools in Barkley Sound was not collected for the current study, and asuitable description of in situ food resources for alternate, comparable field sitescould not be located in the literature;4. that mortality is based solely on the longevity of the organism itself. The influence ofdispersal agents, competition, or predation have not been included in thecalculations; andChapterS: Abundance and Population Flux 1075. that the pool volume may increase from precipitation and evaporate according toaverage climatic conditions (Chapter 3; Appendix B), but remains isolated fromwave action. Further, that the dilution or evaporation imposed no deleteriouseffects.The instantaneous rate of growth, birth, and death for T. californicus populationswas calculated using the formulae of Paloheimo (1974) and Feller (1980). Using theexponential growth equation:Nt=Nt0e7t (1)r is the instantaneous rate of increase, N is the initial abundance of T. californicus (valuesfor Day 1 in Tables 5.3 and 5.4, from a founding population of 10 individuals), and t isthe elapsed time, in days.Instantaneous birth rate (b) was then calculated as:b=ln(E÷1)ID (2)where E is the abundance of eggs (here estimated from clutch sizes under winter andsummer conditions, per Chapter 4), and D is the time of development for the eggs(assumed to be 4 days for T. californicus, from the calculations of Vittor, 1971).From Feller (1980) instantaneous death rate (d) was then calculated as:d=b-r (3)to derive the values of Table 5.5. Finally, the estimated rate of increase (r) was comparedto the observed r for 3 pools on Helby Island in the summer of 1995, as illustrated inFigure 5.1. From Paloheimo (1974, cited by Feller, 1980, p. 463) these calculationsassume a stable age distribution, constant birth and death rates, and fixed eggdevelopment. Feller (1980) suggests such assumptions, though applicable over shortintervals (ca. 1 week), may not apply over longer intervals. Hence, the comparisonillustrated in Figure 5.1 was only plotted for one week of observation.Chapter 5: Abundance andPopulation Flux 108RESULTST. califomicus Abundance: Seasonal T. ca4fornicus abundance is summarized inTable 5.1. Total density remained remarkably consistent over the year, with the exceptionof winter, when it declined to 217 ± 401.7 individuals L from a seasonal means of 757± 2014.5, 835 ± 1750.6, and 644 ± 2220.2 individuals L’ in spring, summer, andautumn, respectively (means rounded to the nearest whole individual). Winterpopulations were also more sporadic in occurrence, concentrated into one-half to one-third of the pools normally occupied in other seasons. With enhanced evaporation andsustained isolation from replenishment in the summer months, I observed populationdensities of up to 200,000 individuals L; the highest value for the current data set was21,456 ± 1750.6 individuals L1, and similar ‘maxima’ were found in autumn, spring, andsummer (Table 5.1).The adult male-to-female ratio remained consistent at 1.36 in spring and summer,increasing to 1.84 in autumn and 1.47 in winter, with several dense populations occurringin coupled (riding) pairs to a significant extent. At the highest densities, samples werecomprised virtually entirely of T. ca4fornicus, predominately of mature individuals, andwith more than 80% of the females carrying egg sacs. Clutch size ranged from 23 ± 6.5eggs female1 in winter to 37 ± 10.2 eggs female in summer.Pool Duration: From the 14-year average precipitation for the area (Table B. 1), apool of typical size of 7.01 m2 in winter and 3.38 m2 in summer (Table 1.2) , wouldreceive 6.8 x 102 L day1 and 8.9 x i0 L day in precipitation. Correcting for theaverage rates of evaporation recorded in Chapter 3, an average-sized T. californicus poolwould evaporate in 8 to 9 days in winter or 4 to 5 days in summer, assuming it is notreplenished by wave action. These and other parameters are summarized in Table 5.2.Population Growth. Tables 5,3 and 5.4 summarize the calculations of totalabundance from a hypothetical founding population of 10 individuals apportioned into theChapter 5: Abundance and Population Flux 109life-history stages derived in Chapter 3 Figure 5.1 summarizes a comparison betweendaily measurements of T. californicus density from 3 randomly-selected Helby Islandpoois and the expected rates of growth, birth and death, using equations I - 3 and themodel assumptions noted above.Population Extinction: For the current analysis, an ‘extinction’ was tallied eachtime a previously inhabited pooi was found to be without T cahfornicus duringsubsequent sampling intervals; the reverse condition was taken to indicate ‘colonization.’Overall, 12 pools were found to contain T. calfornicus during every sampling interval, 12ofthe randomly-selected poois were never observed to contain T. calfornicus, and theremaining 61 pools had intermittent or sporadic habitation. Among the five field sites,pools on Diana Island and Wizard Islet experienced the highest frequency of extinction at48 ± 18% and 33.5 ± 16.6%, respectively (mean ± s.E.). The lowest frequencies ofextinction were observed at First Beach (26.5 ± 15.2%) and Second Beach (29.8 ±7.2%, see Figure 5.2).TABLE5.1.SeasonalTigriopus cahfornicusabundance,differentiatedbygeneralizedlife-historystage.Tabulatedmeanvalueshavebeenroundedtothenearestwholeindividual.Jndividuals/LNaupliiCopepoditesMalesFemalesGravidFemalesClutchSizeInclusiveofstages:(N-ItoN-VI)(C-ItoC-Ill)(C-IVtoC-VI)(C-IVtoC-Vl)(C-IVtoC-VT)(eggs)TOTALaAutumn*mean66928915712329644range(0-100)(0-1250)(0-11,680)(0- 2160)(0-6320)(2-43)(40-20,600)se.17.5151.51248.7293.4693.94.92220.2n88888888882088Winter**mean362362425123217range(0-580)(0-300)(0-500)(0-275)(0-900)(6-29)(8-2440)s.e.117.152.4101.061.5139.73.4401.7n47474747471247Springmean2612128020712331757range(0-886)(0-5000)(0-11,722)(0-4600)(0-6528)(8-34)(10-19,182)s.e.85.4409.4757.5421.2443.73.72014.5n38438438438438475384Summer***mean3111531823513633835range(0-89)(0-5218)(0- 11,244)(0-4350)(0-6118)(22-39)(17-21,456)s.e.89.7381.7728.8422.2438.12.81750.6n44844844844844838448*=values from1994only;**=valuesfrom1995only;atotal individualsU’,excludingunhatchedeggs.=values fromboth1994and1995.Chapter 5: Abundance and Population Flux 111TABLE 5.2. Parameters used for the calculation of in situ population growth and declineof Tigriopus calfornicus. Except where specified, values used were derived in the currentstudy. Standard error (mean ± SE,) or observed range (minimum - maximum) for valuesare provided where applicable; mean values are used for the calculation of Table 5.3.Summer Value(July + August)Winter Value(January)Factor Parameter (units)Basin Volume (L) 8.9 ± 17 5.2 ± 67Surface Area (m2) 7.01 ± 12.5 3.38 ± 6.7Water Temperature (°C) 10.7 (7 - 14) 21.8 (17 - 33)Salinity(%o) 21.4±9.1 40.1± 17.2Precipitation (mm/day) 10.8 ± 5.5 2.6 ± 2.49( LI day)* 6.8 x 10-2 8.9 x i0Volumetric Flux (L /day) 1.10 1.47Pool Duration (days) 8 - 9 3 - 4Population Founding Population 3 male 3 male1 female wI clutch 1 female wI clutch1 female 1 female5 nauplii + copepodites 5 nauplii + copepoditesInitial Count 10 + clutch 10 + clutchn 28 28Sex Ratio (Male:Female) 1.47 1.36Individuals Clutch size (# eggs) 23 ± 6.5 37 ± 10.2Eggmortality(%) 10.8±7.8 10±9.1Duration as Nauplius (days) 12 10Duration as Copepodite (days) 18 11Generation Time (days) 30 21Duration as Adult (days) 35 35Natural Survival (%) 90 90Potential Mates (males) 3 3Potential Broods (females) 3 3* Average daily preciptation in millimeters over the pool surface area indicated.Chapter 5: Abundance and Population Flux 112TABLE 5.3. One week abundance and age structure predicted for Tigriopus calfornicusfounding populations. Assumptions: a founding population of 10 individuals plus averageclutch sizes of 23 (winter) and 37 (summer) from Chapter 4; 10% mortality at hatchingand nauplius/copepodite and copepodite/adult transitions; growth rate per Chapter 4 andan adult longevity of 5 weeks. No predation or decimation due to wave action is includedin the calculation. Density is tabulated as individuals L1.Time After Life-History Whiter SummerFounding Stage (January) (July + August)1 Day Males 3 3Females 2 2Copepodites 3 3Nauplii 2 2Eggs 23 37TOTAL 33 472 Days Males 3 3Females 2 2Copepodites 3 3Nauplii 23 35Eggs 0 0TOTAL 31 433 Days Males 3 3Females 2 3Copepodites 3 2Nauplii 23 35Eggs 0 0TOTAL 31 434 Days Males 3 4Females 3 3Copepodites 3 3Nauplii 22 33Eggs 0 0TOTAL 31 435 Days Males 4 4Females 2 3Copepodites 2 3Nauplii 22 33Eggs 0 0TOTAL 31 436Days Males 4 4Females 3 3Copepodites 2 3Nauplii 22 33Eggs 46 74TOTAL77 1171 Week Males 5 6Females 4 5Copepodites 1 39Nauplii 63 126Eggs 0 0TOTAL 73 176Chapter 5: Abundance and Population Flux 113TABLE 5.4. Five week abundance and age structure predicted for Tigriopus cahfornicusfounding populations. Assumptions per Table 5.3, with the proportion of life-historystages at one week equal to the results of Table 5.3. Density is tabulated as individualsL-1.Time After Life-History Winter SummerFounding Stage (January) (July + August)1 Week Males 5 6Females 4 5Copepodites 1 39Nauplii 63 126Eggs 0 0TOTAL 73 1762 Weeks Males 5 16Females 5 13Copepodites 30 20Nauplii 31 63Eggs 41 100TOTAL 112 2123 Weeks Males 23 27Females 14 21Copepodites 27 57Nauplii 37 90Eggs 62 233TOTAL 163 4284 Weeks Males 36 67Females 25 42Copepodites 33 81Nauplii 56 210Eggs 228 533TOTAL 378 9335 Weeks Males 49 100Females 33 72Copepodites 50 189Nauplii 205 480Eggs 414 1132TOTAL 751 1973Chapter 5: Abundance and Population Flux 114TABLE 5.5. Instantaneous growth, birth, and death rates for founding populations. Meanabundance (total individuals L, based on a founding population of 10 individuals) andclutch size per Tables 5,3 and 5.4 under winter and summer conditions (see Chapter 4).All calculations use time (t) in days; from Vittor (1971), an egg development time of 4days is assumed. See text for other assumptions and formulae.Time Season/Conditions Instantaneous rate Instantaneous Instantaneous(days) (per ChapterS) of increase (r birth rate b) death rate (dI Winter -0.063 0.795 0.858Summer -0.089 0.909 0.9982 Winter -0.031 0.000 0.037Summer -0.044 0.000 0.0443 Winter -0.021 0.000 0.021Summer - 0.030 0.000 0.0304 Winter -0.014 0.000 0.014Summer -0.022 0.000 0.0225 Winter 0.169 0.960 0.791Summer 0.182 1.079 0.8976 Winter 0.132 0.000 -0.132Summer 0.152 0.000 -0.1527 Winter 0.113 0.000 -0.113Summer 0.130 0.000 -0.13014 Winter 0.087 0.930 0.006Summer 0.108 1.177 1.06921 Winter 0.076 1.036 0.960Summer 0.105 1.364 1.25928 Winter 0.087 1.360 1.271Summer 0.107 1.570 1.46335 Winter 0.089 1.507 1.418Summer 0.107 1.758 1.651I 20001000Chapter 5: Abundance and Population Flux 115Figure 5.1. Calculated vs. Observed Change inTigriopus californicus DensityDaysFIGURE 5.1. Calculated versus observed change in Tigriopus calfornicus density. Usingsummertime data, the scored line indicates the predicted change in density from Tables5.3 and 5.4. Solid line represents the observed abundance, as calculated from dailysamples from 3 Helby Island pools. Discrepancies exist due to avoidance of the sampler,and the assumptions of the model (see text). Increases in predicted density (per thecalculations of Table 5.3 and 5.4) derive principally from the production and hatching ofbroods.500040003000-- - PredicteU Actual01 2 3 4 5 6 7Chapter 5:’ Abundance and Population Flux 116IFigure 5.2. Frequency of Pool Extinction with LocationFIGuRE 5.2. Frequency of copepod extinction with location. Average frequency ofTigriopus cahfornicus population extinction for all pools at each field location. For datapresentation, an ‘extinction’ event was tallied when a previously inhabited pooi was foundto have no copepods during a subsequent sampling interval. Values presented as mean ±S.E.First Bh. Second Bh. Wizard It. Helby Is. Diana Is.LocationI806040200Chapter 5: Abundance and Population Flux 117Figure 5.3. Frequency of Pool Extinctionwith Tidal Elevation- All LocationsFIGURE 5.3. Frequency of copepod extinction with tidal elevation. Average frequency ofTigriopus cahfornicus population extinction with shoreline elevation for all pools. Fordata presentation, an ‘extinction’ event was tallied when a previously inhabited pooi wasfound to have no copepods during a subsequent sampling interval. Values presented asmean ± S.E.2m-3m 3m-4m 4m-5m 5m+Tidal Elevation (m)ChapterS: Abundance and Population Flux 118DLscussIoNSampling ConsiderationsSampling Considerations: Perhaps the three most significant obstacles toestimating the microcrustacea populations in situ are: 1) accurate and representativesampling of the organism at all life-history stages; 2) an accurate determination of birthrate; and 3) an estimate of the natural longevity of each age-class, including possiblesources of mortality on juveniles as well as adults. In the first instance, at least a cursoryunderstanding of the organism’s natural history is required for the selection of appropriatesampling gear (sample volume, mesh size, number or replicates). For the derivation ofbirth and death rates, clutch size, egg viability, time of first hatching, and larval survivalcan (and Often are) estimated from organisms in culture under a variety of conditions,however the conditions under which an organism ‘thrives’ may have little or noresemblance to the natural conditions of the organism’s habitat.While T. californicus populations occur largely within the relatively small, discretevolumes of supralittoral splashpools, representative sampling of the organism at all life-history stages cannot be assumed. The organism exhibits a dive-and-cling swimmingbehavior (Egloff, 1966; Vittor, 1971), and an escape response that appears to bestimulated by shadows or microscale changes in hydrostatic pressure. Measures can betaken to prevent undue disturbance of the pools and thus the escape of individuals(particularly adults) from the sampler, however the nauplii and egg stages, which haveless-developed swimming ability, are found in association with the phytobenthos on thebottom of poois and are often much more difficult to collect.The shallow depth of most splashpools precludes the use of more traditionalsieves, nets or pumps, which cannot be properly submerged or maneuvered. Burton andFeldman (1981) collected T. californicus by scooping pools directly into plastic bottles orusing a fine mesh for low-density populations; the method most commonly described forChapter 5: Abundance and Population Flux 119culture specimen collection. Harris (1973) drew 100 mL samples using a 63 im sieve, aprocedure which may not capture all life-history stages of T ca4fornicus. Fraser (193 6a)and Monk (1941) sampled pools by siphoning water through a net or bailing the pooi ofall its water, a procedure which may be disruptive for some applications. Dethier (1980)estimates population numbers from the number of individuals passing over a miniatureSecchi disk, but this method permits enumeration only, without specimen identification toany appreciable degree.I have used, alternately, a calibrated 30-mL pipette or scoops of a 12 cm diameter(400 mL) glass preparation dish for sampling splashpools. The wider catchment area andtransparency of the glass reduces the pressure wave and visual cues produced by thesampler, at the expense of sampling close to the substratum. This latter consideration isnot incidental, as the majority of a population- especially nauphi - may subsist near thebottom of the pool and may be under-sampled unless consideration is given to the suaeeirregularities of the pool basin. The use of a large, calibrated pipette (or turkey baster) ispreferred for drawing a smaller volume of the pool, yielding a discrete, high velocitysample of the substratum which does not damage nauplii or egg sacs, and sampleprocessing time is reduced. Irregular topography and calculations from averageddimensions can produce a high degree of error, and siphoning all the water from a pooimay be the only means to determine pool volume accurately. However, such a degree ofdisturbance to the ecosystem in order to measure a parameter noted to experience daily oreven hourly flux should also be considered.Escape response should be considered as a source of error principally in thecollection of adult specimens, since eggs and nauplii prior to the N-ffl stage do notexhibit directed swimming behavior (Chapter 4). Both Egloff (1966) and Vittor (1971)described a ‘dive and cling’ swimming response of T. caiqornicus to water agitation. Themagnitude of this response will depend on the size of the disturbance produced bysampling, and so care should be taken: 1) to avoid casting shadows; and 2) to avoidChapterS: Abundance and Population Flux 120undue agitation of the water prior to collection; Egloff (1966) used a 0.5 liter bowl andsampling at dusk to compare possible temporal variation. During several nighttimecollections (unpublished data), a flashlight beam trained directly on a swarm of Tigriopusin the water column of their pool produced neither a positive nor a negative phototaxis,possibly indicating that the intensity of the light was not sufficient to elicit phototaxis.Moreover, although T. californicus exhibit this quick-start potential, all stages appear tofatigue quickly and soon settle out when placed in deeper volumes of water. It was notdetermined whether the organism may respond similarly to changes in pressure or lightfrom the non-visible spectra.Mature (copepodite and adult) T. californicus are observed to utilize the fullextent of the ‘water column’ available in their shallow pools, with dense populations oftencoloring the water orange with ‘clouds’ or ‘swanns’ of swimming individuals. Hicks andCoull (1983) and Bell et al. (1988) found mature female copepods to also favor thesubstratum, while males and immature females may utilize the water to enhance theopportunity for pre-copulatory encounters. Feeding of all life-history stages occurs alongthe substratum as the organism browses surfaces for adsorbed bacteria or microalgae,however this does not preclude incidental filtering of materials in solution (Harris, 1973),or the uptake of dissolved organic material (DOM) across the cuticle (Khalov andYerokhin, 1971; Carli et al., 1993).Given the heterogeneity or patchiness of T. californicus populations, a random orstratified-random method for selecting sample locations is the most desirable. Withinpools, patches or aggregations of microbes do not generally predict patches of meiofaunalconsumers (Dauer et al., 1982; Montagna et al., 1983), and the results of the currentthesis (Chapter 2) do not suggest higher densities of T. californicus in association witheither macroalgae or the higher concentrations of organic matter associated withvegetation. Although temporary stratification of splashpools may occur under staticconditions (Morris and Taylor, 1983), this condition is easily disrupted by wind or waveChapterS: Abun&znce and Population Flux 121action, and it could not be determined if the organism associates with microscalethermocines or haloclines within pools’.While the dried algal material used for the experiments of Chapter 3 containedostensibly higher accumulations of T. californicus, this observation is the result ofpopulations being compacted and stranded in a comparatively restricted area due toevaporation of the pool. For this same reason, density of field populations is betterpresented as individuals per unit pool volume, rather than per unit of the volume sampled;samples recorded only as individuals mL1 or L4 may erroneously suggest a bloom ordecline in copepod abundance, when what is actually indicated is evaporation or dilutionof the pool itself. Since pooi volume can change over as little as a few hours, the methodof Chapter 1 (estimating pooi volume from averaged dimensions) should suit mostapplications. Even pumping all the water from a given pool (to derive an accurateestimate of pool volume), may not sufficiently collect all individuals from crevices in theincised bedrock and may even reduce estimates from those obtained from pools sampledwhile filled.Seasonal Abundance and Density of T. californicusIn Fraser’s (1936a) examination of the supralittoral zone, plankton densities werefound to be three to 40 times more dense than littoral collections, and comprised of onlytwo species, compared to 12 species found lower in the littoral zone. Overall, the presentcalculations of population density agree with previously published values for in situconditions (e.g., Harris, 1973; Dethier, 1980). In Barkley Sound, T. californicus appearsto reproduce throughout the year, establishing population density maxima ofapproximately 20 individuals . mL in autumn, spring, and summer. Winter populationsare not only reduced in density by as much as two-thirds (Table 5.1), but are also found infewer pools, with 7’. californicus persisting, but retaining ‘foxholes’ in a smaller number of1 This would be doubtful, given the organism’s demonstrated tolerance to temperature, salinity andpressure under laboratory conditions.ChapterS: Abundance and Population Flux 122habitable reservoirs. Proportions of the life-history stages were also consistent in thesethree seasons, while the representation of nauplii in all seasons was much lower (overallaverage = 28 ± 7.4 individuals L1) relative to copepodite and adult abundance thanwould be expected, for example, in pelagic copepod assemblages (but see Dybdahi,1989).Burton and Feldman (1981) suggested that, while complete extinction ofTigriopus populations is unlikely, regular depletion of populations may occur, either dueto wave activity or seasonal changes in climate and water properties. Dybdahl (1994)considered T calfornicus pools on the same rock outcrop as forming a metapopulation:a collection of local populations experiencing periodic extinction and re-colonization,which is especially characteristic of subdivided or fragmented habitats. He furtherreported extinction ofT ca4fornicus populations in 35% of his study poois over a periodof six to eight weeks. On occasion, I have discovered pools of T cahfornicus whichwere nearly all apparently deceased. Temperature and salinity were not anomalous inthese pools, however this does not preclude the possibility of thermal or haline shockfrom a rapid change in these parameters, or the presence of a localized, unidentifiedpollutant. These pools may also have been evaporated pools recently hydrated by runoffor wave splash (Chapter 3).In Barkley Sound, T. cahfornicus does not appear to exhibit a bloom in numbersduring any season, Although populations may become concentrated into a smallervolume by evaporation, this is not the same as an increase in absolute number. For thisreason, copepod density is more correctly recorded as individuals L per unit poolvolume. Upon finding a splashpool habitable, T calfornicus appears to increase rapidlyin density and remain there until the population is decimated, or spread to another waterdeposit, which agrees with the findings of Vittor (1971).Egloff (1966) suggested that summer populations of Tigriopus ca4fornicus areinfluenced less by storm activity and wave splash. While wave conditions may be lessChapter 5: Abundance and Population Flux 123extreme in the summer, I suggest the influence of evaporation and stagnation may becomemuch more pronounced, particularly in warmer climates. Further, even populations whichare trapped in evaporated pools do not necessarily become ‘extinct,’ as there exists thepotential for individuals to resume normal activity following re-hydration (Chapter 3).Hence, in comparing the conditions of Tigriopus-inhabited pools, parity of season andlatitude between study sites are essential considerations.The male-to-female ratio for the current study averaged 1.41 ± 0.23 for the entireyear, which compares with the findings of Egloff (1966) and Vittor (1971). Adultsfrequently occur almost entirely in clasped (though not necessarily mating) pairs, at timeswith multiple males competing for a single female. Smaller females are also sometimesdifficult to differentiate from copepodites, and this is a potential source of error inpopulation counts. Evaporation has the effect of concentrating those individuals retainedin pools, and will undoubtedly influence oxygen consumption, food resource utilization,and mating behavior among splashpool copepods. At high densities (i.e., those in excessof 20 individuals mL1), density-dependent behaviors such as inhibition of eggdeposition (Kahan et a!., 1988) or maternal cannibalism on nauplii (Lazzaretto andSalvato, 1992), a biasing effect on one or the other gender has not been demonstrated.Estimating Changes in PopulationPopulation Growth andLongevity: In order for birth rate to be determined, the:1) egg number; 2) age at first reproduction; 3) rate of brood production; and 4) sex ratiomust be known. Published accounts of population growth for Tigriopus copepods havebeen less than satisfactory (but see Harris, 1973). Morris et al. (1980, p. 632) claimed T.cahfornicus populations “can double every 6.6 days at 15°C and every 3.9 days at23 °C,” but this claim is unremarkable unless the gender and age structure of the initialpopulation is specified. Dethier (1980) calculated a population gain of 13 copepods L 1Chapter 5: Abundance andPopulation Flux 124day 1, but while this study compared experimental and control pools of equivalentvolumes, no mention is made of physical conditions.Vittor (1971) reported a generation time of 32 days at 15°C and 18 days at 25°C,with a total lifespan time of 130 ± 14 days at 15°C and 80 days at 25°C forT. californicus; Harris (1973) reported a longevity of 55 days at 15°C for T. brevicornis,and Ito (1970) a longevity of 70 days for T japonicus, values that are undoubtedly linkedto rearing conditions beyond temperature alone. Between the sexes, Egloff (1966) foundfemale T. californicus to be longer lived (by 1.9 times) than males, with this effectenhanced at lower temperatures. Under starvation conditions, females were observed tolive 3.7 times as long as males, again at lower temperatures’.From Table 4.1, the egg-to-adult generation time is more than a week longerunder “winter” temperatures and salinity, requiring 30 days for the complete developmentof the organism, compared to 21 days under “summer” conditions. Such a delay could beconsidered disadvantageous during the winter in-si, when storm activity, wave action onthe shore, and hence the potential for wash-out of pool populations may be enhanced.Igarashi (1959) noted an inverse correlation between the frequency of pool flushing andthe age and stability of Tigriopus populations; the effect of wash-out would be magnifiedon younger life-history stages (pre-N-III stage), which have less developed swimmingability (Chapter 4). Conversely, the comparatively more rapid development ofTcab/ornicus under “summer” conditions might be considered advantageous, sincesummertime pools are generally more prone to evaporation.Population Density: Egloff (1966) used triplicate samples of 6 pools to determinethe absolute size of a T. cahfornicus population. His samples ranged from 242 to 1938individuals L-1; conservative estimates, he cautions, due to the organism’s avoidance ofsampling gear. Interestingly, however, this in situ ‘maxima’ closely approximates the five1 This enhanced longevity may be explained by higher levels of polyunsaturated fats in the female, whichmay provide nutrition in the absence of food.Chapter 5: Abunthince and Population Flux 125week total for summer populations calculated here (1973 individuals L, Table 5.4).Dethier (1980) reported in situ T. calzfornicus densities as high as 2333 individuals L4(recorded as 35 individuals. 15 mL’) for spring samples, but did not differentiate theseto life-history stage. The same could be said of most studies, which either omit the size ofthe basin (pool volume), the life-history stage, or all life-history stages in the reporting ofpopulation density.Fecundity and Sex Ratio: Published accounts of sex ratio for Tigriopus copepodsare typically varied. Belser (1959) provided a figure of nearly 4.0 (75 to 80% males) inTigriopus populations (season and species not stated), while Egloff (1966) found a rangeof 1.07 to 5.0 (7- 84% males) in his field populations. Lazzaretto et al. (in press, cited in1990) note a ratio of 1:1 for T. fulvus, which is contrary to the observations of mostnatural populations. Factors contributing to fluctuations in sex ratio or life-history traitsare evaluated extensively in the theses of Egloff (1966) and Vittor (1971), respectively.Differential life span, population density, time of year and longevity of the pool are allresponsible for the observed sex ratios of field populations (see Table 5.2), however sexratios approximating 1:1 may occur in very dense populations, where nearly the entirepopulation may be conjoined in mating pairs (Chapter 4).In populations growing slowly, the percentage of males (which typically maturemore quickly than females) would be expected to increase (Egloff, 1966), which at leastin part explains the decline of sex ratio in the current study from 1.46 in winter to 1.36 insummer. Conversely, sex ratio decreases in rapidly growing populations, or those movinginto increasingly stressful conditions as more females are produced (Egloff, 1966),however the absolute density of females in a population may be more significant than thedensity of females relative to males. Although newly-established populations of lowdensity, as in recently colonized pools, would benefit from a decreased sex ratio (i.e.,having more females), this potential for population growth may not be realized, as theChapter 5: Abundance and Population Flux 126increased production of nauplii may be curtailed by increased instances of maternalcannibalism (Egloff, 1966). Egloff(1966) also found no correlation between sex ratioand population density, however more females were produced under cooler, more salineor darker conditions. He concluded that either 1) males are less resistant to stressfulconditions; or 2) male-to-female conversion is encouraged by stress (cf Vacquier, 1962;Vacquier and Belser, 1965 for response to hydrostatic pressure). The increasedproduction of males at higher temperatures reported by Egloff (1966) was not found inthe results of Vittor (1971).While insemination (and thus egg sac production) may continue to occur even atextremely high population densities, egg deposition appears to be inhibited, as indicatedby the disproportionate abundance of gravid females (and mature life-history stages ingeneral) in dense populations; it is not known for how long the eggs can be carried whilestill maintaining their viability. In general, unstable conditions and increased temperaturewill foreshorten generation time, including the time required for egg hatching (reviewed inWebb and Parsons, 1988). From studies of brood production in Tigriopus copepods(Comita and Comita, 1966; Harris, 1973; Chapter 5), egg size, viability, and clutch sizeare highly variable, but are apparently independent of rearing conditions. Many crustaceaare poikilosmotic, and during high salinity flux, energy may be shifted from reproductionto osmoregulation. Vittor (1971) noted that T calfornicus females are most fecund at150% sea water, however Lee and Hu (1981) found the highest fecundity of 7’. japonicusto occur at 27. l%o to 34.3%o (approximately 100% sea water), though this comparisonignores the potential influences of food availability and other rearing conditions. Withinsome hypersaline pools, increased fecundity may be inconsequential: Dybdahi (1995) notonly finds higher desiccation and osmotic stress in 7’ californicus pools on exposedshores (relative to sheltered locations), but also finds the proportion of females andjuveniles to be lower in these populations and suggests a higher mortality of these life-history stages. In their review of harpacticoid copepods, Hicks and Coull (1983) tabulateChapterS: Abundance and Population Flux 127(from Huizinga, 1971): 3 broods copulation-1and 18 eggs clutch-1 for T cahfornicus,which they consider low to average fecundity when compared to other species.Fluctuation in T. califomicus Populations: Burton and Feldman (1981)suggested that, while complete extinction of Tigriopus populations is unlikely, regulardepletion of populations may occur, either due to wave activity or seasonal changes inclimate and water properties. Using a vital stain, R. Burnett (pers. comm,, cited in Morriset al., 1980 p. 632) observed that the majority of individuals in T calfornicus pools may‘overturn’ within a few days, although the total density of the population remains similar.Dybdahl (1994) reported extinction ofT calfornicus populations in 35% of his studypools over a period of six to eight weeks, however these calculations do not consider theimplications presented in the current study, of desiccation-resistant life-history stages(Chapter 3) or removal by dispersal agents (Chapter 1). From the current results, the“prediction” ofpopulation extinction is virtually impossible without further addressingsuch factors as swimming behavior of T. calfornicus under dynamic conditions andquantification of the effects of pool wash-out at the organismal level..Splashpools on Diana Island and Wizard Islet experienced the highest frequencyof extinction (48 ± 18% and 33.5 ± 16.6%, respectively) and the lowest frequencies ofextinction were observed at First Beach (26.5 ± 15.2%) and Second Beach (29.8 ±7.2%. While this may suggest that exposure to breaking waves increases the frequency ofpopulation extinction, such a conclusion is not supported by Figure 5.4, since the highestfrequency of wave-produced extinction would be expected at or slightly above the meanwater level (see Figure 1.2). Given the ephemeral nature of pool conditions and thesometimes lengthy intervals between sampling, any conclusions of sustained exclusion orinclusion of T ca4fornicus also cannot be supported by these observations.Based on the above calculations and comparisons to field populations, thepredictive ability of calculated growth rates is also probably quite limited, even whenapplied to homogenous patches (inhabited pools) within a larger, heterogenousChapter 5: Abundance and Population Flux 128distribution (patchiness among pools on a given shoreline). However, as noted in thepreceding chapters, T. californicus populations appear able to increase their numbers tolevels in excess of 20,000 individuals• L1 throughout the year, regardless of pool size,tidal elevation, the percent-cover of macrofauna, or initial population number. Whilepopulations may be decimated by sudden changes in the habitat (e.g., heavy runoff, wavesplash, pollutants), the organism possesses an innate ability to bloom from a very smallpopulation of varied life-history stages, to in situ densities that are without equal incoastal or offshore assemblages of microcrustacea.CONCLUSIONSAssuming that the sampling methods used provide representative samples of theabundance and age structure of splashpool populations, calculations of T. californicusgrowth based on in vivo measurements and observations appear to provide a reliableestimation only a portion of the time. Further, pools for which the assumptions of thesecalculations may be applied, namely those pools: 1) high enough to reduce the influenceof dilution by wave splash and runoff; 2) small enough to deter colonization by potentialpredators or competitors; yet 3) large enough to resist complete evaporation are probablythe exception to the norm and are not representative of the vast majority of the localpopulations in Barkley Sound. Ironically, pools that meet all these requirements to besuitable vessels for the study of “natural” populations virtually represent open air cultureflasks, with less stringent control on abiotic variables such as water condition. For thosepools not meeting the above criteria, I suggest that small volume pools (less than about25 L) may be limited most significantly by evapor3tive processes or occasional wavesplash; larger pools may persist under stratified conditions, but food availability may notbe sufficient to support large copepod populations, especially where vegetation orsediment is scarce.Chapter 5: Abunthince and Population Flux 129Regardless of pooi volume or water conditions, T. californicus populations appearable to increase abundance to some in situ maximum, with the carrying capacity of anygiven pool, in the absence of stochastic events, probably dictated solely by the abundanceof suitable food resources. At the highest population densities, egg hatching is apparentlyinhibited and the number of individuals remains at an elevated and consistent level.Complete ‘crashes’ of populations under stable conditions is probably unlikely, howeverthermal or haline shock, or displacement of individuals by wave splash, is undoubtedly aregular occurrence. As discussed in previous chapters of this thesis and studies such asVittor (1971) and Dybdahi (1994), only a small number of dispersed individuals is likelyrequired to colonize new pools, provided pool conditions remain habitable.GENERAL DISCUSSIONThe preceding observations have sought to extend the understanding of variousaspects of the ecology of Tigriopus cahfornicus that have either not previously beendescribed or have not been quantified experimentally. Included among the presentcontributions to the organism’s natural history in Barkley Sound are: 1) a quantifieddescription of the organism’s habitat at intervals throughout the year, as well as thephysical characters of pools within each season; 2) an experimental examination of theapparent lethality of C. trichotoma on T. californicus individuals; 3) desiccationresistance as a mechanism by which T. californicus may persist in splashpools duringtemporary intervals of evaporation; and 4) the population density and approximate agestructure of T. californicus populations throughout the year. Non-experimentaldiscussion has also be presented on: 5) the potentiality of several dispersal agents endemicto the supralittoral habitat in Baricley Sound; and 6) the development of populations fromsmall “founder” populations under temperature and salinity regimes representative ofseasonal norms.This general discussion will briefly summarize the findings of this thesis relative toprevious studies of the ecology of T. californicus and its congeners, note omissions to thepresent work, and suggest avenues of further study.SUPRAL1TTORAL HABITAT CoNDrnoNs IN BARKLEY SOUNDObservations of the supralittoral habitat occupied by T. californicus in BarkleySound are not dissimilar to the general accounts for temperate splashpools providedelsewhere, particularly with regard to general shoreline features and the predominant taxaof macroalgae present (e.g., Fraser, 1936a; Kain, 1958; Gustavsson, 1972; Sze, 1981;Dethier, 1982; Morris and Taylor, 1983; Metaxas and Scheibling, 1993). Indeed, themost striking change in splashpool composition for the field sites is the seasonal130Discussion 131succession of macroalgae described in Chapter 1. However, this “visible difference” insplashpools may only be an ancillary consideration for a given splashpools habitabilitywhen compared to: 1) the direct influence of wave action; and 2) the microflora presentwithin each season.Exposure to Wave Action: The paucity of T. calfornicus poois observed at tidalelevations less than Ca. 3 m corresponds to the regular changes in the mean water levelfor the region. Between 3 and 5 m tidal elevation (from Chapter 1, the elevation at which90% of T. ca4fornicus pools are found), metapopulations may either be decimated(washed-out) or randomly exchanged (mixed) by storm waves or the highest tides. Asobserved by Dybdahl (1994), such conditions may only exist for a few days per tidalcycle, and T. cahfornicus become established only where isolated above the mean hightide level (see Figure 1.2). Above 5 m elevation, the opportunity for splashpools to becreated and maintained is further lessened, and water deposits there are more likelyreplenished by precipitation and runoff. Similarly, Igarashi (1959) concluded that T.japonicus populations were younger and less stable in pools that were more frequentlyflushed by wave activity. Whether an increase in wave splash acts more significantly todecimate populations, or instead encourages the replenishment and genetic exchangebetween pools of a given metapopulation has not been sufficiently established for high-energy shorelines, but see Burton and Feldman (1981); Burton (1986); Brown (1991);Dybdahl (1994, 1995).The irregular, incised features of the rocky shorelines of these study sitesprecludes the designation of generalized basin types (one suggested classification isillustrated in Figure C. 1 and applied in Table C. 1). Regardless of the designation forbasin type (shape) used, any increase or decrease in the volume of pool water will changethe basic bathymetry, and in turn, the calculation of pool water volume. Although anaccurate determination of pool volume may be possible only by pumping all water out ofthe pool, this does not ensure sampling splashpool copepods any more efficiently thanDiscussion 132with the methods of Chapter 5. Regardless of the sampling technique used, a reasonableestimate of pooi volume is essential to derive Tigriopus population density within anephemeral and highly variable pool volume to avoid erroneous conclusions of populationflux based on individuals per volume sampled (Chapter 3). In contrast to oceanicsamplers, for which an accurate determination of the water volume sampled is essential,the volume of water within which the sampler is deployed is the parameter of interest forestimating population density from littoral or supralittoral pools. Further, and distinctfrom most littoral pools, splashpools generally have a closed basin, which permitsreplenishment only from the surface. The infiltration of sea water through cracks ortunnels worn in the rock (possibly carrying predators or permitting an escape route for T.californicus from inhospitable conditions) is not evident, and so the nature of the air/poolinterface becomes particularly important when considering the habitability of splashpools.Certainly the volume, surface area, temperature and salinity of a pool willinfluence the habitability of the pool for T. californicus as well, but the extreme andrecurrent flux in these parameters makes their selective influence difficult to track (but seeDybdahl, 1995). The large surface area-to-volume ratio of typical T. californicus pools inBarkley Sound (averaging 7.06, from Chapter 1) enhances the rate of evaporation butalso provides a large interface with the atmosphere, providing an ample source of oxygento support high densities of T. calfornicus and possibly counteract the activity of bacteriain isolated and stagnant poois. Additionally, the smaller volume and shallow depth ofthese splashpools serves to discourage or prevent habitation by larger predators such assculpins and anemones (Dethier, 1980).Vegetation and Food Resources: As with the physical parameters of pool water,T. ca4fornicus habitation is not apparently dependent upon any taxa of macroalgae.From Chapter 1, thriving populations of T. californicus are found in all seasons andregardless of the predominate vegetation (with the exception of C. trichotoma, fromChapter 2). Thriving populations were often found in pools containing no vegetationDiscussion 133beyond benthic diatoms and microalgae. Although the taxa and abundance of microfloracan be expected to vary with season and tidal elevation (e.g., Sze, 1981; Metaxas andLewis, 1992), an analysis of the microflora available to T. californicus in the splashpoolsof Barkley Sound was not part of the current thesis, hence an estimate of the natural foodresources available to the organism is not included here (but see below). Gibor (1956),Provasoli et al. (1959) and the studies listed in Table 4.2 are among the legions ofattempts to identify the ‘preferred’ food of Tigriopus species, but as with analyses of thetolerance of the congeners, treatments do not typically approximate natural conditions.Recent work by Carl et aL (1993) addresses T. fulvus feeding on in situ concentrations ofVibrio bacteria, and Lee and Taga (1988) present several strains of bacteria isolated fromT. japonicus pools as “effective” food, but obviously the microflora available to thecopepod will depend on season and location. The density of the ambient food resourceswill further depend on the stability of the pool and the amount of dethtus or sediment itcontains (see below).POPULATION STRUCTURE AND FLUXThe results of Chapters 4 and 5 agree favorably with previously published resultsfor T. calfornicus field populations, including Egloff (1966) and Vittor (1971). FromMacArthur and Wilson (1967, discussed in Vittor, 1971), the rapidity of organismdevelopment and extension of the reproductive interval will act to increase fecundity; inturn, fecundity is enhanced by increasing the number of clutches, rather than the numberof clutches per female. Female T. californicus may produce up to 20 broods (Vittor,1971), and with the species’ remarkable fecundity and short generation time, couldostensibly produce 10 to 15 generations per year. While the clutch size can varyconsiderably between individuals or successive broods (see Comita and Comita, 1966,and the citations in Chapter 5), whether brood production does vary substantively will bea function of rearing temperature, food availability, and population density.Discussion 134The results of this thesis suggest that this copepod reproduces throughout theyear, but ostensibly attains a maximum in situ density of ca. 20 individuals mL in allseasons but winter. In winter, the number of colonized pools may be significantlyreduced, but dense T. californicus populations may still result, even in very small poolscontaining no macroalgae. In addition, the extremely high proportion of gravid femalespresent in such populations provides a remarkable potential for repopulation, shouldredistribution occur by hydrochore or biochore dispersal. Whether redistributed randomlyby wave action (e.g., Dybdahl, 1994), trapped in a basin that ultimately evaporates, orcarried as incidental ectoparasites on other organisms, T ca1fornicus has demonstratedthe ability to recover viable populations from a very small number of colonists (Vittor,1971; Dybdahl, 1994; Chapter 3), and may procreate more successfully with intra-poolmates than via the random exchange of individuals between pools of a givenmetapopulation (Brown, 1991). Under hospitable conditions, the organism appears toflourish to an in situ maximum of ca. 20 individuals mL, whereupon egg deposition isinhibited and the cohort ages to become predominately adult males and females (possiblywithin 2 - 3 weeks, from Chapter 4).It is at this point that other density-dependent processes may become morepronounced. To extrapolate the findings of cannibalism and maternal inhibition in high-density populations ofT fulvus (e.g., Lazarretto and Salvato, 1992; Kahan et al., 1988),T californicus females apparently retain their egg sacs until the time of their eventualdeath. As mentioned in Chapter 3, dehydrated T. calfornicus do not drop their egg sacs,but hatching may occur soon after rehydration. This contrasts with the egg depositionand hatching that occurs almost immediately following sacrifice of gravid females, andmay provide a more acute indication of death in the parent. Provasoli et al. (1959) alsosuggest that hatching in T. californicus and T japonicus is induced by light, however Iam not aware of experimental confirmation of this.Discussion 135Burton and Feldman (1981) noted the difficultyin drawing conclusions aboutgenetic structure from discrete observations. They suggest that since T. californicus isfree swimming throughout its life history, dispersal might be expected, provided it is nottoo costly to the organism.’. Burton and Feldman (1981) further suggest that gene flowamong all pools on an outcrop, with similarities in gene frequencies explained by foundereffects or localized similarities in water properties and meteorological conditions.Battaglia et al. (1978) also ascribed the genetic variability of Tigriopus underconditions of continued stress to individual plasticity. This work also provides a relativelyrare genetic comparison between species of the genus - that of T. fulvus from Leghorn,Italy, with T. brevicornis from Tavvallich, Scotland, and a further comparison ofTigriopus with Tisbe species2. Battaglia et al. (1978) also noted that genetic variabilitydecreases with temporal constancy of the environment; the more exacting theenvironment, the more strategies are based upon individual flexibility, not geneticplasticity. They conclude that Tigriopus likely has a fixation of generalist alleles, ratherthan any sort of genetic homeostasis. In exchange, the organism may have a lowtolerance to biotic diversity, and be a poor competitor (Battaglia et al., 1978, and not, tomy knowledge, confirmed experimentally). This is in agreement with theoretical naturalselection in harsh or variable environments, whereby a few genotypes producing flexibleor plastic phenotypes would be favored (sensu Pianka, 1970). Bottlenecks or decimationof populations are a common occurrence under the stressful conditions of the supralittoralzone, and genetic drift or founder effects have been suggested to explain the low geneticvariability in field populations3 (Egloff, 1966; Vittor, 1971; Battaglia et al., 1978; Burtonand Feldman, 1981; Dybdahi, 1994).Egloff (1966) found a mean egg development time of 2.4 days at 23°C, 4.8 daysat 15°C and 8.2 days at 10°C for T. californicus, and calculates the total development1 Brown (1991) determined that such outhreeding apparently is costly to 7’. ca4fornicus.2 Sampling of each species, however, occurred at only one field location.Bias inherent in the sub-sampling technique may also lead to bias in conclusions about sex or age.Discussion 136time as 16.5 days at 23°C, or 27.5 days at 15°C. There is no periodicity of egg laying,and the potential for various life-history stages to be introduced to a pool at the same timemay ensure that sex ratio variability and differential age structure are continued (Egloff,1966). In general, reproductive rate increases with temperature and egg number, anddecreases with sex ratio - with the influence of the former conditions being greater thanthat of the latter (Egloff, 1966). Egloff (1966) noted that while more females meansenhanced growth of a population, predation by the females on nauplii will also increase.Hence, the absolute density of females in a population may be more significant than thefemale density relative to males (sex ratio). Certainly, newly-established populations oflow density, as in recently colonized pools, would benefit from a decreased sex ratio (i.e.,having more females). In populations growing more slowly, the percentage of males(which typically mature more quickly than females) would be expected to increase, whileconversely, sex ratio decreases in rapidly growing populations, or those moving intoincreasingly stressful conditions (discussed in Egloff, 1966).BEHAVIOR OF THE ORGANISMFeeding: The feeding of T. caljfornicus is not yet resolved. Although theorganism has demonstrated feeding on a number of items in culture, the preferred diet forfield populations has not been established. Although some studies have addressed thefeeding preference of Tigriopus species (Gibor, 1956; Provasoli, 1959; Carli et al., 1993),I suggest that T. calilfornicus is a detritivore, razing and subsisting upon the bacteria andbenthic diatoms growing on the bottom of pools.The feeding appendages of T. caljfornicus appear to be ideally oriented to providea “groove” for razing epiphytic growth from filamentous macroalgae such asEnteromorpha or Scytosiphon (L. Chatters, A. G. Lewis, pers. comm.). However, giventhe general paucity of macroflora in pools supporting thriving T. calfornicus populations(Chapter 1 and 2), it would appear that the copepod can feed equally well by browsingencrusting algae (such as Ralfsia-like crusts) or other phytobenthos attached directly toDiscussion 137the bedrock. Given this diverse potential for grazing, why T. californicus apparently doesnot browse C. trichotoma filaments is still unclear. As discussed in Chapter 2, either: 1)the filaments of C. trichotoma may not support the epiphytic growth preferred by T.califomicus; or 2) given the rapidity with which 7’. californicus populations decline whenexposed to C. trichotoma, some chemical agent that is deleterious to T. calfomicus mayindeed be responsible.Swimming: A dive-and-cling swimming response to shadows or pressuredisturbances has been observed in Tigriopus californicus (Egloff, 1966; Vittor, 1971) andfor harpacticoid copepods in general (Hicks and Coull, 1983). While the organism hasbeen observed to ‘crawl’ easily over a variety of surfaces and textures, it is doubtful thatthe behavior is sufficient to retain the organism’s position in a pool, especially duringstorm events. Wash-out of pools is noted by Igarashi (1959), Dethier (1980), Burton andFeldman (1981), but as stated above, it is not known how long T. californicus mightremain in the plankton without being culled by any number of agents.The magnitude and rapidity of the ‘dive and cling’ response of T. californicus topooi disturbance has not been tested for harpacticoids (but see Richardson, 1992). As anatural reaction to escape predation or survive wave disturbance, the dive and clingbehavior also serves to confound the accurate census of splashpool populations. Whilethe pipette method described in ChapterS still under-represents actual abundance to somedegree, it does draw material from along the substratum, making it more effective thanscoops or dipnets for sampling all life-history stages. A waterproof video camera couldbe used in a splashpool to observe the use of the water column by the various life-historystages under undisturbed conditions, provided a suitable lens and camera housing couldbe found for use on high-energy shorelines.Thigmotaxis: As noted above, the clinging behavior noted in response to pooldisturbance may also assist in the biochore dispersal of T. californicus. By clinging to thecarapaces of crabs, the gills of fish, or even the feet and plumage of shore birds, it isDiscussion 138possible that a few individuals could be dispersed far beyond the inshore circulation ofwave activity. Tigriopus calfomicus nauplii are observed to be thigmotactic whenoffered to larval fishes; 7’. californicus respond aggressively to the presence of fish, oftengrasping the gills and operculae, although the copepodite stages have been successfullyused in the diet of older fish larvae (Morris, 1956; reviewed by May, 1970). When notconsumed by fish, it is possible that this same behavior may assist in distributing thecopepods in limited numbers on migrating fish. However again, unless eventuallyreleased very close to a suitable refuge, it is doubtful that the copepod could survive longin the water column.Chemotaxis: Particularly in aquatic environments, chemically-mediated behaviormay promote either the dispersal or homing response of an organism. Although sexualdimorphism is not visually apparent in T. calfomicus until the C-IV stage, males appearable to recognize ‘potential females’ as early as the C-I or C-il stage; chemical signalingby the female may be the stimulus for these responses; male specimens do not appear torelease any signaling compounds (Lazzaretto et al., 1990). Lazzaretto et al. (1990) testedT. fulvus for 1) offspring recognition and 2) species recognition (between T. fulvus, T.californicus and T. brevicornis) and found the response to previously inhabited containerswas species specific, and that aggression of the females was noted towards non-relatednaupili (a behavior also noted by Egloff, 1966). Further, nauplil placed in mediumwithout gravid females were noted to ‘disappear,’ while late N-stage and copepoditestages did not (Lazzaretto et al., 1990).The work of Kahan et al. (1988) propose the transmission of inhibitory messagesto the egg sac in T. japonicus. This work further suggested that the ‘hook-like’ structuresleading into the egg sac, and described by Fahrenbach (1962) may be the structureconducting such messages from the mother. At high population densities (greater than 50individuals . L1), the deposition of eggs appears to be inhibited, while the number ofnauplil hatching was observed to increase over time. The laying of eggs then appears toDiscussion 139he inhibited, not promoted. In field populations, an inordinate number of egg-carryingfemales is noted, supporting this notion. However, regardless of density, eggs will hatchto nauplii within an hour once the mother is killed.Once relocated into a new pool, chemical secretions may provide an indication ofthe pool’s habitability. Bozic (1975) describes an ‘aggregation pheromone,’ wherebyTigriopus (I assume fulvus) demonstrates a preference for vessels containing waterpreviously inhabited by the same species. Dethier (1980) proposes that displaced T.californicus may be able to locate their home pool or detect refugia which previouslysustained copepod populations. I have observed T. californicus to congregate aroundpreviously-inhabited Petri dishes mounted in 25 L aquaria flooded with artificial sea water(unpublished data) and do not dismiss chemically-mediated behavior as an effective agentover short distances and under tranquil conditions. From Bozic (1975) chemicalsecretions by as few as 20 copepods have permeated smooth, solid test chambers in aslittle as 15 hours; Dethier (1980) suggests the concentration of chemical signals from adensely populated pool could be considerable. As discussed in Chapter 2, the combinationof chemical agents in a stagnant splashpool must be diverse and confusing to a potentialcolonist. For individuals washed out of a pool on an isolated outcrop, it is even moreunlikely that attractive scents could be detected by the copepod and followed successfullyback to a previously inhabited pool, given the size of the individual against that of themaelstrom.DISTRIBUTION OF THE GENUS AMONG SIMILAR HABITATSObservations of the ecosystem particular to Barkley Sound have provided severalpotential agents for dispersing T. ca1fomicus, some suggested here for the first time.The innate physical tolerance, comparatively short generation time, and high fecundity ofT. californicus would allow it to readily colonize any habitable coastal pools, withlocalized extinction and vicariance events eventually producing the current globaldistribution for Tigriopus species. From Chapter 3, only 100 to 150 T. caiqornicusDiscussion 140retained by a bird (or birds) foraging in the supralittoral zone would be sufficient toprovide dispersal in this manner. At the in situ population densities T californicus mayattain (often in excess of 20 individuals L, with a mean in excess of 750 individualsL1 over much of the year), such estimates are not unreasonable and provide an avenueworth further examination.Figure GD. 1 provides a simplified account of how T. ca4fornicus and itscongeners may have become dispersed by avian carriers within the past Ca. 8,000 years(i.e., utilizing the current coastlines and position of continental land masses in theNorthern Hemisphere). For the current discussion, Figure GD. 1 does not presume toillustrate the origin or cladistics of Tigriopus congeners, but illustrates how the copepodcould be transported incidentally along the migratory corridors of several bird species.For all practicable purposes, metapopulations of T cahfornicus may still beconsidered “genetically isolated [and] currently undergoing independent evolution,” asBurton (1986, p. 532) suggested. From the limited data available for the current thesis,the potentiality of avian carriers is put forth as reasonable speculation; gradual dispersalor punctuated instances of gene flow by avian carriers would be virtually impossible todetect without radio-tracking and recapture of the birds, and genetic or vital staincomparisons of the copepods themselves.Follow-up experimentation on the viability of these various agents is clearlyneeded, with particular attention to I) the transport ofT californicus by incidentalvertebrates and invertebrates; and 2) the potential for metapopulation dispersal bylongshore transport. Suggestions include detailing the home range of crabs, birds, orshoreline vertebrates that traverse rocky shores occupied by T cahfornicusmetapopulations. The resistance to desiccation noted in Chapter 3 provides a plausiblemechanism for the organism to survive inhospitable conditions, and perhaps evenextended air transport. Once deposited in a new pool, the re-animated individuals possessan equally remarkable potential to rapidly increase their numbers (Chapters 4 and 5), andDiscussion 141FIGURE GD.1. Proposed dispersal routes of Tigriopus congeners by avian carriers. Allcurrently extant species may well have arisen from a single locale, then dispersed andbecoming genetically isolated under the influence of local selection pressures. Squareindicates the location of the current study area.Discussion 142providing a theoretically stable colonizing population with a diversity of life-historystages.TOLERANCE OF THE ORGANISMApropos to the extreme conditions of its natural habitat, Tigriopus expressesconsiderable euryhaline and eurythermal endurance. Temperature and salinity act asselective agents on polymorphism as well as genetic variability (Battaglia, 1970). In bothfield and laboratory studies, water temperature can influence differences in the equilibriumfrequencies of genes which control polymorphism (Battaglia and Lazzaretto, 1967, ascited in Battaglia, 1970).Given this, a fundamental impetus for the series of observations and experimentspresented in this thesis is to assist the development of future laboratory studies thatprovide experimental regimes representing more closely the natural conditions found inthe habitat of T. californicus. Numerous studies using T. californicus have provided dataon the organism’s tolerance and response to a broad range of temperature and salinityregimes, but these have not necessarily been indicative of in situ conditions:Salinity: McDonough and Stiffler (1981) tested the organism’s osmoregulationover a salinity range of 60 to 300%c. Huizinga (1971) found a salinity tolerance in T.calefornicus over a range of 21.2 to 75.3%o, with ‘optimum’ activity at 42.3 to 47%. Incontrast, Takano (1968) found optimal salinity conditions for T. japonicus to be slightlyless than 100% sea water. Ranade (1957) tested the tolerance of T. fulvus over a salinityrange of 0 to 225% at 16-18 °C. Survival of individuals was reported as 60 hours at98%, 30 hours at 1 80% and 3 hours at 255%, although salinities in excess of 90%produced ‘apparent death’ in most individuals. Issel (1914) found T. fulvus to have atolerance to salinities in excess of 190% and also notes a condition of ‘apparent death,’from which the organism can awaken and regain normal activity when the water issufficiently diluted. Egloff (1966) found T. californicus to resume normal activityDiscussion 143following dilution from 334%o, and Kasahara and Akiyama (1976) reported similarobservations for T. japonicus, however Chapter 3 of this thesis has provided the firstquantified account of this response (to duration and life-history stage) and the first recordof in situ re-animation for the genus.Ranade (1957) also noted that dried splashpools replenished only by rain watercould retain populations of T. fulvus, an observation which is further discussed in Chapter3. Indeed, the response of the organism to fresh water has been less clearly documented,and may be even more deterministic to the organism’s survival than hypersalineconditions. Ranade (1957) noted T fulvus to perish in distilled water within 84 h.Igarashi (1960) tested T. japonicus over a range of 5 to 180% sea water, and found alower salinity tolerance of 3.4%o; Lee and Hu (1981) provided an even lower threshold of1.8%o for the same species, and I have found T calfornicus populations in pools with asalinity of<1%o, as determined by refractometer or measurements of conductivity.Igarashi (1960) found gravid T. japonicus to lose their eggs sacs at low salinities, as wellas a delay in spawning recruitment (relative to 80% and 100% sea water) but found noapparent correlation between salinity and sex ratio.Igarashi (1960) also found that spawning recruitment occurred earlier at 80% and100 % sea water, which compares with Takano’s (1968) results. Conversely, Egloff(1966) found a negative correlation between salinity and sex ratio, indicating that Tcalfornicus females are more tolerant to high salinities. In field populations, higher poolsalinity (from evaporation) corresponds to evaporation, which is enhanced at highertemperatures. Egloff(1966) and Vittor (1971) find more males are produced at highertemperatures (with a shorter generation time, egg to C-VI adult), hence the overall effecton sex ratio may be inconsequential, as the time of relatively higher salinity tolerance forfemales corresponds to the comparatively greater production of males. As thereproductive potential of the population is thus enhanced, individuals are also constrainedDiscussion 144to a smaller volume of water as the pooi evaporates, producing the sometimesphenomenal population densities reported in the literature and in the present thesis.The salinity of a splashpool may be quickly reduced by intense precipitation oreven normal sea water waves diluting a hypersaline water deposit, while increases insalinity may occur from 1) sea water infiltrating a pooi filled with comparatively freshwater; 2) runoff carrying salt encrustation into a pool; or 3) gradually, from evaporation.Egloff (1966) performed natural (evaporative) salinity changes, beginning at 43%o.Activity was still evident at 102%o (37 days later), but ceased at 200 % (44 days). Theexperiment was ceased at 56 days at 334%o, and the organism was re-animated by normalsea water. Egloff(1966) also experimented with T calfornicus survival after 30 minutesof exposure to desiccation at 60 and 100% relative humidity, and found egg sacs torespond best to drying, while nauplii experienced the highest mortality. I did not findeggs to respond following drying, and noted copepodites to revive the most quickly fromre-hydration, most likely from their larger surface area: volume ratio (see Chapter 3).Temperature: The small volume and high surface area of a typical splashpoolmakes it particularly susceptible to changes in temperature due to solar heating, coolingby wind, or even complete freezing. Ranade (1957) reports T fulvus heat tolerance atover 40°C. He also observed a ‘death point’ temperature at which Ca. 75% of theexperimental individuals died within a temperature change of 0.1°C. He does notelaborate further on this observation, and used only two samples. Kontogiannis (1973)described acquisition of heat tolerance in T cahfornicus from 0 to more than 30°C,including thermal shocks of 10°C. A lower temperature threshold has not been published,however in casual experimentation, I have suspended T calfornicus in ice, to have itresume normal activity once thawed. For the current field sites, it is doubtful that pooltemperatures ever exceed 30 to 35°C, however this does not lessen the influence ofevaporation from exposure. Moreover, temperature changes occur much more quickly,Discussion 145and one would expect thermal shock to be more common and more extreme than halineshock.Excepting the action of pollutants, a rapid change (cooling) in pool temperaturefrom wave splash may be the only explanation for observations of splashpool Tigriopuspopulations which appear to be all, or apparently all, dead. As with any microscalechanges in pool water condition, the small, isolated volume of splashpools leaves themparticularly susceptible to the action of pollutants. OErien et al. (1988) found T.californicus able to tolerate cupric ion activity two to three orders of magnitude greaterthan other copepods, including Acartia, Calanus, Euchaeta, Labiodocera and Metridiaspp.4 Again, while providing impressive results of what the organism can tolerate, few ofthese experiments have been devised with the intent of approximating the conditionsfound in supralittoral splashpools (i.e., what the organism does tolerate).Somewhat paradoxically, given the demonstrated hardiness of the genus topollutants and physico-chemical stress, Tigriopus congeners continue to be utilized asindicator species for pollutant studies, including population response to contaminatedsediments (LeDean and Devineau, 1985; Pacquet and Lacaze, 1988; Misitano andSchiewe, 1990; Pacquet and Lacaze, 1990; Pavillon et al., 1990), even though sedimentaccumulation is rarely observed in supralittoral pools, at least in the study sites I selectedin Barkley Sound. As noted by O’Brien et al. (1988), the use of an exceptionally tolerantorganism as an indicator species in bioassays or lethality tests can, depending on thestudy, significantly bias the recommendations derived from the observed results. Whilestill formidably suited to studies in ecology, fisheries, genetics, and use as a bioassayorganism, further empirical analyses of the organism’s response to realistic and controlledin situ environmental conditions are clearly needed if the ecology of this copepod is to bedetailed further.Perhaps not surprisingly, since copper and chlorine levels are typically much higher in splashpoo]s,due to frequent and repeated evaporation of a comparatively small volume.Discussion 146To conclude, I must extend my regards to Dr. Brian Marcotte, whom I have nevermet, for his 1977 dissertation “The ecology of meiobenthic harpacticoids (Crustacea,Copepoda) in West Lawrencetown, Nova Scotia” (Dalhousie University, Halifax, N.S.).Though addressing considerably different aspects of harpacticoid ecology, and distancedfrom the present thesis by nearly two decades and the entire breadth of this country,Marcotte’s work was instrumental in the prose and process of the current manuscript. Itis Marcotte’s work that first acquainted and attracted me to the field of harpacticoidbiology, and it remains nearly without equal as a tome that so completely discusses itssubject while paying homage to the scientific, artistic, and humanistic factors inspiringendeavors such as ours. This philosophy is embodied in the following excerpt fromMarcotte’s (1977) preamble:The world of these ancient argonauts is a thousand micron sea.It is a world of flake and stone, or crystalline herbs and truffledgardens, of thimble mountains and ever-shifting sand.It is not the pickled muds museum’s house,just as human society is not a city morgue.Rather, their world can only be understood as they would live init: sense it, explore it, eat, rest, reproduce.Meiobenthic harpacticoids are not distributed in space and time,they are space and time. Their physiology, morphology andbehavior define the dimensional space in which they live and ofwhich their evolutionary history can only hint.Meiofauna adapt not in time but embody it; size and communitystructure are the sensible beat of their clock. In short, theirphysics exists only in so far as they live, and our understanding of-them exists only in so far as we can take on their life.For this end, the present thesis begins.— B. M. MARCOTrE (1977)Appropriately, with these same words, the present thesis ends.LITERATURE CITEDAdams, H., 1907. The education of Henry Adams, p. 16Anderson, J. W. and G. C. Stephens, 1969. Uptake of organic material by aquaticinvertebrates VI: Role of epiflora in apparent uptake of glycine by marine crustaceans.Marine Biology (Berlin) 4: 243-249.Ar-rushdi, A. H., 1958. The polygenic basis of sex-ratio in Tigriopus. Proc. Xiii liii.Congr. Genetics. 2: 8 (Abstract).Baker, C. F., 1912. Notes on the crustacea of Laguna Beach. First Ann. Rep. 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The Vancouver Island coastalcurrent: fisheries barrier and conduit, p. 265-296. In: Beamish, R. 3. and G. A.McFarlane (eds.) Effects of ocean variability on recruitment and an evaluation ofparameters used in stock assessment models. Can. Spec. Publ. Fish. Aquat. Sci. 180.Thomhill, R. and I. Alcock, 1983. The Evolution ofInsect Mating Systems. HarvardUniversity Press, Cambridge. 547 pp.Underwood, A. J., 1981. Structure of the rocky intertidal community in New SouthWales: patterns of vertical distribution and seasonal changes. J. Exp. Mar. Biol. Ecol.51: 57-85.Literature Cited 160Vacquier, V. D., 1962. Hydrostatic pressure has a selective effect on the copepodTigriopus. Science 135: 724-725.Vacquier, V. D. and W. L. Belser, 1965. Sex conversion induced by hydrostatic pressurein the marine copepod Tigriopus californicus. Science 150: 1619-1621.Vilela, M. H., 1984. Production experimenis of the marine harpacticoid copepodTigriopus brevicornis Mueller, reared on various feeding regimes. Bol. Inst. Invest.Pescas Port. 11:83-115.Vittor, B. A., 1971. Effects of the environment on fitness-related life history charactersin Tigriopus californicus. Ph.D. thesis, University of Oregon, Eugene.Waaland, J. R., 1977. Common Seaweeds of the Pacjfic Coast. J. 3. Douglas Ltd.,North Vancouver.Ward, H. B. and G. C. Whipple, 1959. Freshwater Biology, 2nd ed. Edmonson, W. T.(ed.) John Wiley & Sons, New York.Watanabe, T., T. Arakawa, C. Kitajima, K. Fukusho, and S. Fujita, 1978. Nutritionalquality of living feed from the viewpoint of essential fatty acids for fish. Bull. JapanSoc. Sci. Fish. 44: 1223-1227.Webb, D. G. and T. R. Parsons, 1988. Empirical analysis of the effect of temperature onmarine harpacticoid development time. Can. J. Zool. 66: 1376 - 1381.White, J. R. and M. R. Roman, 1992. Egg production by the calanoid copepod Acartiatonsa in the mesohaline Chesapeake Bay: the importance of food resources andtemperature. Mar. Ecol. Prog. Ser. 86: 239-249.Wiebe, P. H., 1970. Small-scale spatial distributions in oceanic zooplankton. Limnol.Oceanogr. 15: 205-217.Woodin, S. A., 1978. Refuges, disturbance, and community structure: a marine soft-bottom example. Ecology. 59: 274-284.Woodin, S. A., 1981. Disturbance and community structure in a shallow water sand flat.Ecology. 62: 1052-1066.Wulff, F., 1972. Experimental studies on physiological and behavioural responsemechanisms of Nitocra spinipes (Crustacea: Harpacticoida) from brackish-waterrockpools. Marine Biology (Berlin). 13: 325-329.Zar, 3. H., 1984. BiostatisticalAnalysis, 2nd Edition. Prentice-Hall, New Jersey.718 pp.ZoBell, C. E. and E. C. Allen, 1935. The significance of marine bacteria in the fouling ofsubmerged surfaces. J. Bact. 29: 239-251.APPENDIX A: LOCATION MAPS161FIGURE A.1. Location of study pools on Diana Island. Numbers correspond to thedesignation and position of pools monitored over the duration of the study. Upper portionillustrates to the northeast portion of Kirby Point; lower section illustrates the southwestportion of Kirby Point on the western edge of the island. Thumbnail map shows relationof study site to the area described by Figure 1.1.Appendix A.• Location Maps 162FIGURE A.2. Location of study pools on First Beach. Numbers correspond to thedesignation and position of pools monitored over the duration of the study. Thumbnailmap shows relation of study site to the area described by Figure 1.1.Appendix A.• Location Maps 163PlatformSand BeachTo Bamfielil—Inlet25 mFIGURE A.3. Location of study pools on Helby Island. Numbers correspond to thedesignation and position of pools monitored over the duration of the study. Thumbnailmap shows relation of study site to the area described by Figure 1 1.Appendix A.• Location Maps 164ResidenceSand BeachTree :Gravel Backshore- -.FIGURE A.4. Location of study pools on Second Beach. Numbers correspond to thedesignation and position of pools monitored over the duration of the study. Thumbnailmap shows relation of study site to the area described by Figure 1.1.Appendix A: Location Maps 165, To First BeachTree imeBedrock PlatfoimSand Beach25 mAppendix A.• Location Maps 166FIGURE A.5. Location of study pools on Wizard Islet. Numbers correspond to thedesignation and position of pools monitored over the duration of the study. Thumbnailmap shows relation of study site to the area described by Figure 1.1.Appendix A.• Location Maps 167FIGURE A.6. Location of supplemental study pools on San Juan Island, Washington. A and Bcorrespond to the location of n 6 pools at each site, monitored hourly for changes in temperature,salinity, and Tigriopus abundance during February, 1995 Pools at each site were located withinca. 10 m of each other. The Friday Harbor Laboratories location represented a sheltered coastline,in contrast to the comparatively exposed coastline at Cattle Point. Thumbnail map illustrates theposition of the San Juan Islands group (not illustrated in Figure 1.1).San Juan IslandAPPENDIX B: WEATHER AND TIDE DATA168Appendix B: Weather and Tide Data 169TABLE B.1. Rainfall at Bamfield (in mm) 19731986*. Source: Western CanadaUniversities’ Marine Biological Station (WCUMBS), Bamfield, B.C.YEAR JAN. FEB. MAR. APR MAY JUN JUL AUG SEP OCT NOV DEC1973 507.7 199.6 304.0 59.7 216.4 124.2 46.5 17.0 89.4 384.6 428.2 605.31974 429.3 576.3 590.8 226.6 273.6 98.8 130.8 3.8 82.6 82.9 465.1 530.41975 296.7 218.7 250.2 138.9 168.2 88.9 16.0 203.2 7.9 674.4 661.7 474.01976 400.3 406.4 383.0 147.8 180.3 112.3 67.3 140.5 55.4 234.1 157.2 315.51977 185.2 367.8 330.7 130.3 220.7 59.4 60.2 67.8 84.3 322.8 502.9 268.01978 236.5 214.9 283.7 153.4 124.0 107.7 5.3 254.0 213.9 100.3 218.4 226.81979 89.9 518.2 216.7 140.5 100.8 83.3 88.9 30.5 230.4 242.3 223.3 639.31980 217.9 312.4 248.9 227.6 58.1 62.4 119.6 65.8 165.1 134.0 491.6 603.01981 128.0 319.6 238.1 388.0 136.0 195.6 284.0 56.0 222.5 425.4 389.8 382.01982 510.8 521.4 171.4 216.9 42.8 52.0 59.0 43.2 79.8 426.2 340.2 446.21983 547.4 620.6 425.4 111.8 104.0 128.2 213.6 43.2 88.8 221.6 662.6 167.41984 513.6 413.4 290.6 327.2 265.0 83.2 19.0 55.8 144.2 447.6 435.0 309.81985 76.6 175.6 247.1 202.2 66.2 49.7 8.2. 45.2 91.4 409.2 130.6 155.61986 450.6 358.0 435.2 219.0 323.2 107.4 52.0 12.0 88.8 123.6 460.2 489.6* Data for these particular years are presented as they were readily available and are often referencedfrom WCUMBS Bamfield.Appendix B: Weather and Tide Data 1701994Jan. Feb. Mar. Apr. May. Jun. Jul. Aug. Sept. Oct. Nov. Dec.— — — —WINTER SPRNNG SUMMER AUTUMNJan. Feb. Mar. Apr. May. Jun. Jul. Aug. Sept. Oct. Nov. Dec.1995FIGURE B.1. Seasonal sampling intervals in 1994 and 1995. Blackened sections representsampling periods in Barkley Sound, typically of six to 18 days duration. Half-tone sectionindicates timing of supplemental data collection on San Juan Island in Washington State.Appendix B. Weather and Tide Data 171TABLE B.2. Summary of key weather conditions during sampling intervals. All valuespresented as mean values ± 1 standard error from daily weather data, as available,Detailed weather data could not be obtained for all sampling intervals, including those atFriday Harbor Marine Laboratories (Friday Harbor, WA), in February, 1995. Source:Environment Canada weather offices in Port Albemi and Vancouver, B.C.PARAMETER JULY, 1994 AUGUST, 1994 NOVEMBER, 1994 JANUARY, 1995Daily High (°C) 18.0 ± 0.7 19.5 ± 0.9 10.4 ± 0.5 9.3 ± 1.7Daily Low(°C) 9.8 ± 1.6 9.1 ± 1.3 2.5 ± 2.0 1.7± 4.6Mean(°C) 13.9±4.4 14.3±5.6 6.4±4.4 5.5±5.2POP(Probabilityof 15±5% 25±20% 65±40% 65±40%Precipitation)Actual Precipitation(mm/day) 0 0.6± 0.8 10.7± 17.4 8.8± 9.1Wind Moderate Light and Varible Shifting winds, Moderate toNorthwesterl (5 - 10 knots) Northwesterlies to Strongies Moderate 20 knots Southeaterlies(15 knots) Northwesterlies (15 - 25 knots)Sunrise 05:30 06:28 07:11 08:16Sunset 21:26 20:23 17:02 16:43HoursofSun 7.6±3.0 8.9±2.4 3.6±4.2 2.5±3.0Ultraviolet Index 6.9 ± 0.2 5.6 ± 0.5 N/A N/AAppendix B. Weather and Tide Data 172TABLE B.3. Tide conditions in Barkley Sound durmg sampling. Values (in meters)corrected for local conditions by DFO (1994, 1995) and N. J. Wilimovsky. HHW =Highest, High Water; LHW = Lower, High Water; HLW = Higher, Low WaterLLW = Lowest, Low Water. Time of highest and lowest daily tide also noted ason table (correct +1 hour for daylight time: 3/4/94 to 30/10/94; 2/4/95 to 29/10/95).Month Date 1111W LHW HLW LLWApril 1 3.5 03:25 2.7 1.5 0.5 10:221994 2 3.2 04:29 2.6 1.6 0.7 11:283 3.0 05:38 2.6 0.8 0.8 12:404 2.9 06:57 2.7 1.6 0.9 13:525 2.9 08:14 2.8 1.6 0.9 14:546 2.9 22:08 2.9 1.4 0.9 15:447 3.0 22:43 3.0 1.2 0.9 16:268 3.1 23:14 3.0 1.0 1.0 04:519 3.2 23:42 3.0 1.0 0.9 05:2910 3.0 12:17 3.0 1.1 0.8 06:0311 3.3 10:00 3.0 1.2 0.7 06:3712 3.3 00:38 2.9 1.3 0.7 07:1013 3.3 01:07 2.8 1.4 0.7 07:4314 3.3 01:37 2.7 1.5 0.7 08:1815 3.2 02:10 2.7 1.6 0.8 08:5516 3.1 02:47 2.6 1.7 0.9 09:3717 3.0 03:30 2.5 1.8 0.9 10:2618 2.9 04:24 2.5 1,7 1.0 11:2319 2.8 05:33 2.6 1.0 1.0 12:2720 2.8 20:12 2.7 1.6 1.0 13:3121 3.0 21:01 2.8 1.4 0.9 14:2922 3.2 21:45 2.9 1.1 0.9 15:2223 3.5 22:28 3.0 0.9 0.8 16:1124 3.7 23:10 3.1 0.9 0.4 04:5825 3.8 23:53 3.1 0.9 0.2 05:4626 3.1 12:56 3.1 1.0 0.0 06:3327 3,8 00:38 3.1 1.1 -0.1 07:2128 3.8 01:24 3.0 1.2 0.0 08:0929 3.6 02:12 2.9 1.3 0.2 09:0030 3.4 03:05 2.8 1.5 0.4 09:54Highest 3.8 3.1 1.8 1.0Lowest 2.8 2.5 0,8 -0.1Avg. 3.2 2.8 1.3 0.7s.d. 0.3 0.2 0.3 0.3(continued)Appendix B. Weather and Tide Data 173TABLE B.3. (continued)Month Date HHW LHW HLW LLWMay 1 3.1 04:03 2.7 1.6 0.6 10:591994 2 2.9 05:14 2.7 0.8 0.8 12:023 2.8 19:47 2.7 1.5 0.9 13:054 2.9 20:39 2,7 1.4 1.1 14:045 3.0 21:21 2.6 1.2 1.1 02:546 3.0 21:58 2.7 1.2 1.1 03:447 3.1 22:31 2.7 1.2 0.9 04:278 3.2 23:02 2.8 1.3 0.8 05:069 3.3 23:33 2.8 1.4 0.6 05:4110 2.8 12:40 2.8 1.4 0.6 06:1611 3.3 00:04 2.8 1.5 0.5 06:5012 3.3 00:36 2.8 1.5 0.5 07:2313 3.3 01:10 2,7 1.6 0.5 07:5814 3.2 01:46 2.7 1.6 0.6 08:3415 3.1 02:25 2.7 1.6 0.6 09:1316 3.0 03:10 2.7 1.6 0.7 09:5617 2.9 04:04 2.8 1.6 0.8 10:4618 2.8 18:28 2.7 0.9 0.9 05:0919 3.0 19:24 2.6 1.4 1.0 12:4120 3.2 20:17 2.6 1.2 1.0 13:4221 3.4 21:07 2.7 1.1 0.9 02:5222 3.5 21:55 2.7 1.1 0.5 03:4923 3.7 22:42 2.9 1.1 0.2 04:4124 3.8 23:29 3.0 1.1 0.0 05:3025 3.0 12:47 3.0 1.2 -0.1 06:1826 3.8 13:37 3.0 1.2 -0.1 07:0627 3.7 01:05 3.0 1.2 0.0 07:5328 3.5 01:56 3.0 1.3 0.1 08:4129 3.3 02:48 2.9 1.4 0.3 09:3030 3.1 03:44 2.9 1.4 0.6 10:2031 2.9 17:54 2.8 0.8 0.8 11:12Highest 3.8 3.0 1.6 1.1Lowest 2.8 2.6 0.8 -0.1Avg. 3.2 2.8 1.3 0.6s.d. 0.3 0,1 0.2 0.4(continued)Appendix B: Weather and Tide Data 174TABLE B.3. (continued)Month Date HHW LHW HLW LLWJuly 1 2.9 18:42 2,4 1.3 1.3 12:031994 2 2.9 19:32 2.3 1.5 1.2 01:323 3.0 20:22 2.3 1.6 1.1 02:334 3.0 21:10 2.3 1.6 0.9 03:285 3.1 21:54 2.4 1.6 0.8 04:166 3.2 22:35 2.6 1.6 0.6 04:577 3.3 23:15 2.7 1.5 0.5 05:348 3.4 23:54 2.7 1.5 0.4 06:099 2.8 13:10 2.8 1.4 0.4 06:4210 3.4 00:34 2.9 1.3 0.4 07:1511 3.3 01:15 3.0 1.2 0.4 07:5012 3.2 01:59 3.1 1.2 0.5 08:2613 3.1 15:38 3.1 1.1 0.6 09:0514 3.2 16:24 2.9 1.0 0.7 09:4815 3.2 17:14 2.7 0.9 0.9 10:3616 3.2 18:11 2.5 1.1 1.1 11:3217 3.3 19:12 2.4 1.3 0.8 01:0518 3.3 20:15 2.4 1.4 0.6 02:1619 3.4 21:15 2.5 1.4 0.4 03:2020 3.5 22:11 2.7 1.3 0.3 04:1721 3.5 23:04 2.8 1.2 0.2 05:0722 3.5 23:54 2.9 1.2 0.1 05:5223 3.0 13:01 3.0 1.1 0.1 06:3524 3.5 00:41 3.1 1.1 0.2 07:1525 3.4 01:27 3.1 1.1 0.4 07:5326 3.2 02:11 3.1 1.1 0.6 08:3027 3.0 15:30 3.0 1.2 0.8 09:0528 3.0 16:07 2.7 1.2 1.0 09:4029 2.9 16:47 2.5 1.2 1.2 10:1730 2.9 17:33 2.3 1.4 1.4 11:0031 2.8 18:28 2.2 1.6 1.2 00:36Highest 3.5 3.1 1.6 1.4Lowest 2.8 2.2 0.9 0,1Avg. 3.2 2.7 1.3 0.7s.d. 0.2 0.3 0.2 0.4(continued)Appendix B: Weather and Tide Data 175TABLE B.3. (continued)Month Date HI{W LHW HLW LLWAugust 1 2.9 19:35 2.2 1.7 1.1 01:451994 2 3.0 20:34 2.3 1.7 1.0 02:543 3.0 21:26 2.4 1.7 0.9 03:464 3.2 22:12 2.6 1.6 0.7 04:305 3.3 22:55 2.7 1.6 0.7 05:076 3.4 23:37 2.8 1.3 0.5 05:417 3.0 12:37 3.0 1.2 0.4 06:158 3.4 00:19 3.1 1.0 0.4 06:499 3.4 01:03 3.2 0.9 0.4 07:2310 3.3 14:25 3.3 0.8 0.5 08:0011 3.4 15:07 3.1 0.8 0.7 08:4012 3.3 15:52 2.9 0.9 0.8 22:2613 3.3 16:45 2.7 1.1 0.8 23:3314 3.2 17:45 2.4 1.3 1.3 11:1215 3.2 18:54 2.4 1.4 0.7 00:4816 3.2 20:04 2.4 1.5 0.6 02:0217 3.3 21:09 2.5 1.4 0.5 03:0918 3.3 22:07 2.7 1.3 0.4 04:0519 3.4 22:59 2.9 1.2 0.4 04:5320 3.4 23:46 3.0 1.1 0.3 05:3521 3.1 12:32 3.1 1.0 0,4 06:1422 3.4 00:30 3.2 0.9 0.5 06:4923 3.3 01:11 3.2 0.9 0.6 07:2224 3.2 14:10 3.1 0.9 0.8 07:5425 3.1 14:42 3.0 1.0 1.0 21:0326 3.0 15:15 2.7 1.2 1.1 21:4727 3.0 15:51 2.6 1.4 1.2 22:3728 2.9 16:36 2.4 1.6 1.2 23:3929 2.8 17:33 2.3 1.7 1.7 11:0830 2.8 18:42 2.2 1.8 1.2 00:5231 2.8 19:52 2.3 1.8 1.1 02:02Highest 3.4 3.3 1.8 1.7Lowest 2.8 2.2 0.8 0.3Avg. 3.2 2,7 1.3 0.8s.d. 0.2 0.3 0.3 0.3(continued)Appendix B. Weather and Tide Data 176TABLE B.3. (continued)Month Date 1111W LHW HLW LLWNovember 1 3.5 10:05 3.1 1.0 0.5 16:361994 2 3.7 10:46 3.2 1.0 0.2 17:233 3.8 11:29 3.8 1.0 0.1 05:184 3.9 12:13 3.2 1.1 0.0 18:565 3.9 12:59 32 1.2 0.0 19:446 3.7 13:47 3.1 1,2 0.1 20:347 3.5 14:39 3.1 1.4 0.3 21:278 3.3 15:37 3.0 1.5 0.5 22:249 3.0 16:44 2.9 1.6 0.8 23:2610 2.9 06:12 2.8 1.6 1.6 12:1111 3.0 07:15 2.7 1.4 1.0 00:3112 3.0 08:10 2.7 1.2 1.1 14:3313 3.1 08:57 2.7 1.2 1.1 15:2714 3.2 09:37 2.8 1.3 0.9 16:1115 3.3 10:12 2.9 1.3 0.7 16:5016 3.4 10:44 2.9 1.4 0.6 17:2617 3.4 11:16 3.4 1.5 0.6 18:0118 3.4 11:47 3.0 1.5 0.5 18:3419 3.4 12:19 2.9 1.6 0.5 19:0720 3.4 12:52 2.9 1.6 0.6 19:4021 3.3 13:27 2.9 1.7 0.7 20:1422 3.2 14:05 2.9 1.7 0.8 20:5023 3.1 14:47 2.8 1.7 0.9 21:3024 2.9 15:37 2.8 1.7 0.9 22:1525 2.9 05:05 2.8 1.7 1.1 23:0626 2.9 05:58 2.7 1.6 1.6 12:1127 3.0 06:52 2.6 1.3 1.2 00:0528 3.2 07:46 2.7 1.2 1.0 14:2729 3.4 08:37 2.8 1.2 0.7 15:2430 3.6 09:26 2.9 1.3 0.4 16:15Highest 3.9 3.8 1.7 1.6Lowest 2.9 2.6 1.0 0.0Avg. 3,3 2.9 1.4 0.7s.d. 0.3 0.2 0.2 0.4(continued)Appendix B: Weather and Tide Data 177TABLE B.3. (continued)Month Date HHW LHW HLW LLWJanuary 1 3.9 11:43 3.1 1.3 0.0 18:321995 2 3.8 12:32 3.2 1.2 0.0 19:163 3.7 13:21 3.3 1.2 0.2 19:594 3.5 14:10 3.3 1.2 0.4 20:425 3.3 03:13 3.3 1.3 0.6 21:246 3,2 03:58 3.0 1.3 0.9 22:067 3.2 04:43 2.7 1.4 1.2 22:518 3.1 05:31 2.5 1.4 1.4 23:399 3.0 06:22 2.3 1.3 1.3 13:1610 3.0 07:16 2.3 1.6 1.2 14:2311 3.1 08:10 2.4 1.7 1.1 15:2112 3.1 09:01 2.6 1.8 0.9 16:0913 3.2 09:47 2.7 1.8 0.8 16:5014 3.3 10:28 2.8 1.7 0.7 17:2715 3.4 11:07 3.4 1.6 0.6 18:0016 3.5 11:44 2.9 1.6 0.5 18:3017 3.5 12:21 3.0 1.5 0.5 19:0118 3.4 12:59 3.1 1.4 0.5 19:3119 3.4 13:38 3.1 1.4 0.6 20:0320 3.2 14:21 3.2 1.3 0.7 20:3821 3.3 03:10 3.0 1.2 0.9 21:1622 3.3 03:51 2.8 1.2 1.0 21:1623 3.3 04:37 2.6 1.2 1.2 11:1224 3.3 05:32 2.4 1.4 1.0 12:2525 3.3 06:34 2.4 0.9 0.9 13:4126 3.4 07:41 2.5 1.5 0.7 14:5127 3.5 08:46 2.7 1.6 0.5 15:5128 3.6 09:46 2.9 1.5 0.3 16:4229 3.7 10:40 3.0 1.4 0.2 17:2930 3.7 11:32 3.7 1.2 0.2 18:1231 3.7 12:20 3.2 1.1 0.2 18:53Highest 3.9 3.7 1.8 1.4Lowest 3.0 2.3 0.9 0.0Avg. 3.4 2.9 1.4 0.7s.d. 0.2 0.4 0.2 0.4(continued)Appendix B: Weather and Tide Data 178TABLE B.3. (continued)Month Date HHW LHW HLW LLWFebruary 1 3.6 13:10 3.3 1.1 0.3 19:371995 2 3.4 13:55 3.4 1.1 0.5 20:143 3.4 02:38 3.2 1.1 0.8 20:504 3.3 03:15 3.0 1.1 1.0 21:255 3.2 03:53 2.7 1.3 1.2 10:156 3.1 04:33 2.5 1.5 1.3 11:127 3.0 05:19 2.3 1.7 1.3 12:198 3.0 06:15 2.3 1.3 1.3 13:349 2.9 07:19 2.3 1.8 1.2 14:4310 3.0 08:23 2.5 1.9 1.0 15:3811 3.1 09:18 2.6 1.8 0.9 16:2212 3.2 10:05 2.8 1.7 0.8 16:5913 3.3 10:47 2.9 1.6 0.6 17:3214 3.4 11:27 3.4 1.4 0.6 18:0215 3.4 12:06 3.1 1.3 0.5 18:3316 3.4 12:46 3.2 1.1 0.6 19:0517 3,4 13:28 3.3 1.0 0.6 19:3818 3.4 02:00 3.2 0.9 0.8 20:1419 3.4 02:38 3.0 0.9 0.9 08:5520 3.4 03:19 2.8 1.1 0.9 09:4821 3.4 04:07 2.6 1.3 0.9 10:5022 3.3 05:03 2.4 1.5 0.9 12:0123 3.2 06:10 2.4 0.8 0.8 13:2024 3.2 07:24 2.6 1.6 0.7 14:3325 3.3 08:37 2.7 1.6 0.6 15:3526 3.4 09:40 2.9 1.4 0.5 16:2727 3.5 10:36 3.1 1.2 0.4 17:1228 3.5 11:26 3.5 1.1 0.4 17:52Highest 3.6. 3.5 1.9 1.3Lowest 2.9 2.3 0.8 0.3Avg. 3.3 2.9 1.3 0.8s.d. 0.2 0.4 0.3 0.3(continued)Appendix B: Weather and Tide Data 179TABLE B.3. (continued)Month Date HHW LHW HLW LLWApril 1 3.4 00:43 3.1 1.1 0.6 07:101995 2 3.4 01:19 3.0 1.2 0.7 07:463 3.3 01:50 2.8 1.4 0.7 08:224 3.2 02:22 2.7 1.5 0.8 09:005 3.1 02:56 2.6 1.6 0.9 09:426 3.0 03:36 2.5 1.8 1.1 10:307 2.8 04:25 2.4 1.8 1.2 11:298 2.7 05:27 2.5 1.2 1.2 12:359 2.7 06:42 2.6 1.8 1.2 13:4110 2.7 21:09 2.7 1.7 1.1 14:3611 2.9 09:01 2.8 1.5 1.0 15:2312 3.1 22:24 2.9 1.2 0.9 16:0513 3.4 23:00 3.0 0.9 0.9 04:3914 3.5 23:38 3.1 0.9 0.6 05:2215 3.2 12:21 3.2 0.9 0.4 06:0516 3.7 00:17 3,2 1.0 0.2 06:5017 3.7 00:58 3.1 1.1 0.1 07:3618 3.7 01:42 2.9 1.2 0.2 08:2419 3.6 02:30 2.9 1.3 0.2 09:1620 3.4 03:23 2.8 1.5 0.4 10:1321 3.2 04:24 2.7 1.5 0.6 11:1622 3.0 05:36 2.8 0.7 0.7 12:2523 2.9 20:13 2.8 1.5 0.8 13:3324 3.0 21:06 2.8 1.3 0.9 14:3525 3.1 21:50 2.8 1.1 0.9 15:2826 3.2 22:29 2.9 1.0 0.9 04:1027 3.3 23:03 2.9 1.0 0.8 04:5428 3.3 23:36 3.0 1.1 0.6 05:3329 2.9 18:05 2.9 1.2 0.5 06:1030 3.4 00:07 2.9 1.3 0.5 00:07Highest 3.7 3.2 1.8 1.2Lowest 2.7 2.4 0.7 0.1Avg. 3.2 2.8 1.3 0.7s.d. 0.3 0.2 0.3 0.3(continued)Appendix B. Weather and Tide Data 180TABLE B.3. (continued)Month Date HHW LHW HLW LLWJuly 1 3.2 01:42 2.9 1.4 0.6 08:211995 2 3.0 10:00 2.9 1.4 0.6 08:543 3.0 16:06 2.9 1.3 0.8 09:304 3.0 16:49 2.7 1.2 0.9 10:115 3.0 17:38 2.6 1.0 1.0 10:576 3.1 18:33 2.4 1.2 1.1 00:137 3.2 19:32 2.4 1.3 0.9 01:238 3.4 20:31 2.4 1.3 0.7 02:319 3.5 21:28 2.6 1.3 0.4 03:3210 3.6 22:23 2.7 1.3 0.2 04:2711 3.7 23:16 2.9 1.2 0.0 05:1812 3.0 12:32 3.0 1.1 -0.1 06:0513 3.7 00:08 3.1 1.0 -0.1 06:5114 3.7 00:59 3.2 1.0 0.0 07:3615 3.5 01:50 3.2 1.0 0.2 08:2016 3.3 02:42 3.2 1.0 0.4 09:0417 3.1 03:35 3.0 1.1 0.7 09:4818 3.1 17:07 2.7 1.1 0.9 10:3319 3.0 17:57 2.5 1.2 1.2 11:2220 3.0 18:51 2.3 1.4 1.1 00:4421 2.9 19:47 2.3 1.5 1.1 01:5122 3.0 20:41 2.3 1.6 1.0 02:5323 3.0 21:30 2.4 1.6 0.9 03:4624 3.1 22:15 2.5 1.6 0.7 04:3125 3.2 22:55 2.6 1.5 0.6 05:1026 3.3 23:33 2.7 1.4 0.5 05:4527 2.8 12:41 2.8 1.4 0.5 06:1728 3.3 00:11 2.9 1.3 0,5 06:4729 3.3 00:48 3.0 1.2 0.5 07:1730 3.2 01:26 3.0 1.2 0.6 07:4731 3.1 14:46 3.1 1.1 0.7 08:19Highest 3.7 3.2 1.6 1.2Lowest 2.8 2.3 1.0 -0.1Avg. 3.2 2.7 1.3 0.6s.d. 0.2 0.3 0.2 0.4Appendix B: Weather and Tide Data 181TABLE B.4. Tide conditions at Friday Harbor, Washington. Values (in meters) arecorrected for Friday Harbor Laboratories for February, 1995. HHW = Highest, HighWater; LHW Lower, High Water; HLW = Higher, Low Water; LLW = Lowest,Low Water. Time of highest and lowest daily tide also indicated from tide tables.Source: University of Washington Friday Harbor Marine Laboratory.Date HHW LHW HLW LLWFeb.l 2.7 17:23 2.2 1.3 0.0 23:592 2.7 18:59 2.1 1.1 0.3 11:533 2.6 19:17 1.9 1.0 1.0 13:434 2.5 20:21 1.8 0.8 0.6 01:135 2.5 21:38 1.7 0.9 0.7 03:266 2.4 23:24 1.7 1.2 0.6 15:267 2.4 09:3 1 2.4 1,5 0.5 17:178 2.3 00:20 1.8 1.7 0.4 18:129 2.2 11:20 2.0 1.8 0.3 19:0310 2.2 11:43 2.2 1.9 0.2 19:4811 2.3 12:42 2.2 1.8 0.1 20:3312 2.3 04:25 2.1 1.8 0.0 21:1213 2.4 04:49 2.1 1.7 0.0 21:4814 2.4 05:12 2.1 1.5 0.0 22:2315 2.4 05:35 2.1 1.3 0.0 22:57 FuliMoon16 2.5 06:00 2.1 1.1 0.2 23:3217 2.5 06:26 2.0 1.0 0.4 11:1718 2.5 06:55 2.0 0.7 0.6 12:5919 2.5 07:24 1.9 0.5 0.5 13:4520 2.5 07:56 1.9 1.0 0.4 14:4021 2.5 08:31 1.9 1.3 0.3 15:3722 2.5 09:12 2.5 1.6 0.1 16:4423 2.4 10:02 2.0 1.8 0.0 17:5024 2.4 11:06 2.2 1.9 0.0 18:5425 2.4 02:49 2.3 1.8 0.0 19:5226 2.5 03:32 2.3 1.7 0.0 20:4527 2.5 04:09 2.3 1.5 0.0 21:3428 2.5 04:42 2.2 1.3 0.1 22:16Highest 2.7 2.5 1.9 1.0Lowest 2.2 1.7 0.5 0.0Avg. 2.4 2.1 1.4 0.3s.d. 0.1 0.2 0.4 0.3APPENDIX C: SUPPLEMENTAL DATA182Appendix C: Supplemental Data 183BowlCrescentCrevasseDendriticIrregularLadleFIGURE C.1. Generalized splashpool basin types. Designations illustrate the categories ofsplashpool shape used for the descriptions of Table C. 1. Note that in some instances, thebasin ‘type’ may change according to the volume or depth of water contained within thebasin, particularly on a heavily incised or jagged bedrock platform.Appendix C: Supplemental Data 184TABLE C.1. (begins page over). Summary of pool conditions. Season indicated per thesampling intervals of Figure B. 1. Pool # indicates location (D = Diana Island; FB FirstBeach; H = Helby Island; SB = Second Beach; W = Wizard Islet) and pool number fromFigures A. 1 to A.5. Elevation = tidal elevation of pool, in meters; Basin = Basin type, perFigure Cl; Windbreak = direction of predominate windbreak(s) or higher elevationrelative to the pool; SA = pool surface area; Vol. = pool volume. Presence and census ofTigriopus californicus by generalized life-history stage based on the average result ofreplicate pipette samples. #/L = total number of T. cahfornicus per liter sampled; #/pool =total individuals per liter extrapolated to the total pooi volume. For brevity, the tabulatedvalues represent the combined, averaged values for each pool in each season, however notall pools tabulated were sampled in each season. Teal? = presence or absence ofT. ca4fornicus during sampling; Male, Female = adult stages (C-TV to C-VI); Ovig. Fem.= ovigerous females; Cop’dite stages C-I to C-IV, unidentified to gender; Naupili =stages N-I to N-VT inclusive.TABLEC.1.Summaryofpoolconditions.(Legendonpreviouspage).SeasonPool#Elev.(m)BasinWindbreakSA(m2)Vol.(L) Cop’diteNauplii#/poolSpring1994D13.7Dendriticn/a2251125nD22.9Crescentn/a0.854.25y14.3000014.3607.75D33.7Irregulars0.641.28y7.100007.190.88D45.2se2.55nD55.1s0.752.25nD63.5n212nD75.2Irregularn,e,w,s36648y57.121.421.414.300370008D85.3Crevassesw0.651.3y35.,e312y49.914.,se0.683.4y4525150501530H14.4Dendriticn,w0.53y92.821.47.135.714.314.32784H23.5Crescentsw15120y507.114.30028.660000H33.9Crescentn/a0.52nH44.5Ladlen,ne1575y14.30014.30010725H53.8Irreg./Dene0.753.75nH62.5Bowlse0.450.45y57.17.107.1042.9256.95H72.7Irregulars648nH83.9Ladles0.510nH95Bowl,Jrn510y14.20007.17.11420H104.5Irregularn0.53y42.80021.414.37.11284H114.1Irregularn0.61.8y14.3000014.3257.4H123.3Bowlsw0.84y21.4000021.4856H133.2Irregularn/a0.10.4y7.100007.128.4W13.8Irregularnw,e0.515nW23.8Irregularne1.632nW44Irregularnw0.52.5nW53.8Crevassen,s0.150.75nW64.5Irregulars216y7.10007.101136W73.8Bowle,w315y264.392.9107.1035.728.639645W83.5Irregularsw0.483.36y75402015002520I c-) 00 JI(continued)TABLEC.1.(continued)SeasonPool#Elev.(m)BasinWindbreakSA(m2)Vol.(L) Cop’diteNauplil#/poolSpring94W92.8Irregularn/a10y42.,w1050y57.121.414.3021.4028550Summer1994D13.4Dendriticn/a50300n0000000D23.2Irregularn/a0.422.1y66.633.333.30001398.6D33.7Irregulars2.2513.5nD43.9Crevassese00nD52.8Bowlse0.1891.13nD64.4Bowln0.19251.35y898.5397307.7123.170.8012107.3D75Irregularn,e,w,s218y4002251252525072000D84.4Crevasses,w0.0360.04y128065643296960460.81)93.8Irregularw0.843.36y48019016053.376.7016128D103.7Crevassene,sw0.41.2y50022024040006000D114Crevassen,s5.549.5y20010075250099000FB128Bowln/a072.1y2501257505005250F.B22.8Irregularn/a630y250125100250075000FB32.9Bowln/a6120y585.7317162.98025.70702840FB42.2Bowln/a2100y15050001000150000FB52.9Irregularn/a420y100000100020000FB62.9Irregularn/a1.57.5y140060060020000105000F1372.9Crevassen/a16nFB82.9Irregularn/a1.174.68y25012512500011700FB93.2n/a0y426.6213163.313.336.7069322.5FB102.3n318y133.310033.300023994FB112.3n/a2.515y466.7267133.366.70070005(continued)TABLEC.1. (continued)SeasonPool#Elev.(m)BasinWindbreakSA(m2)Vol. (L) Cop’diteNauplii#/poolSummer94H14.4Dendriticn,w0.480.96y7.1007.10068.16(continued)H23.5CrescentSw0.1350.41y21.,sw0.20.4y10020206000400II53.8Irreg./Dene1.13.3y220.186.786.726.76.713.37263.3H62.5Bowlse0.66nH72.7Irregulars3.535n0000000H83.9Ladles1.0521nH95Bowl,Irreg.n0.0250.03nH104.5Irregularn00nH114.1Irregularn0.3851.54nH123.3Bowlsw0.667.26y5025250003630H133.4Irregularn/a00y133.466.766.70000SB13Crevassee10420y433.426710066.7001820280SB23Irregularn9216nSB34s236y3001501252500108000SB44Irregulars24720nSB53.9Crevassew6.75540nSB64.5Irregularn0.63nSB73.8Ladlen/a4108y80035030015000864000W13.5Irregulars1.625.6y21.4000021.45478.4W22.8Irregularn226y21.4000021.45564W33.3Ladles1.29.6nW44Irregularnw2.428.8y42.9000042.912355.2W53.8Crevassen,s1.210.8nW64.5Irregulars0.356.3y14.27.17.1000894.6W73.8Bowle,w0.94.5nW73.8Bowle,w12240n(continued)TABLEC.1. (continued)SeasonPool#Elev.(m)BasinWindbreakSA(m2)Vol.(L) Cop’diteNauplii#/poolSummer94W83.5Irregular(continued)W92.8IrregularW103.9IrregularW113.9IrregularW122.5IrregularW133.5IrregularW142.2BowlW153.9Crevassen/an/a S se se nn,e,,w w n’s S s,es,ew,ew,en’s n’s n n’sn/a330y11.111.101.68y14.3001.66.4n0.62.4y14.27.17.1141120y28.521.47.10ii2.510y100000n2.816.8y766.73001000.552.75y11353452801.616y275125500.5951.79n0.20.6n0.241.44n30600n1.758.75y0.8256.6y17.1205.2n550n0.563.36n0.2252.03ii4.233.6y200751001.26y175100500.090.54y4751502251.0513.65y583.42921750.42.8y1505050120y16040400.562.8y200.166.766.700033300014.31144000340.8000319200055100020010066.71288061853101531212.5075254400025006720025001050075250256516.7505079634.12525042004040032000066.705602.8SW n/an/an/an/a e n e,wAutumn1994D13.4DendriticD23.2IrregularD33.7IrregularD43.9CrevasseD52.8BowlD64.4BowlD75IrregularD84.4CrevasseD93.8IrregularD114CrevasseD123.2BowlD135.5IrregularD143.2CrevasseD156.7DendriticD166.7DendriticD173.9CrevasseD184.6IrregularD195.4IrregularD204.8CrevasseFB12.8Bowl1505066.733.3009900Pt 00 00(continued)TABLEC.1. (continued)SeasonPool#Elev.(m)BasinWindbreakSA(m2)Vol. (L) Cop’diteNauplii#/pooln/a SW n/a n n/anen/anW ne n/an/an/a Sn,W SW n/an,Swe se S S n n n SW n/an,e,wn’s ne,sw124202.8182 01.438.581.355. y283.4117116.7425175100150755010050251005025550125250075042000500036450005001700410025252601000070200250122502507840500363000126.257.1076284752550160650150050602040600260140475175175y y n y y n n y y n y01000080120755006300000109200051480025650Autumn94FB32.9Bowl(continued)FB42.9BowlFB52.9IrregularFB63.5IrregularFB73.1CrevasseFB82.9IrregularFB93.2IrregularFB103.2DendriticFB113.2DendriticFB122.6IrregularFB132.6IrregularFB142.6IrregularFB152.2IrregularH14.4DendriticH23.5CrescentH33.9CrescentH44.1CrevasseH53.8Irreg‘DenH62.5BowlH72.7IrregularH83.9LadleH95Bowl,IrH104.5IrregularH114.1IrregularH123.3BowlH133.4IrregularH145.2DendriticH154.7IrregularH164.4IrregularH174.7Irregular25 0 0 1251.7617.6n1.59y847.64142501.837.8y425125150216n2.512.5n0.82.4y283.315077.81.518n2.54022.222.211.16799.200(continued)TABLEC.l.(continued)Autumn94H184.7Bowl(continued)H192.9Bowl?H192.9Bowl?H204.9DendriticSB12.9IrregularSB22.9IrregularSB34IrregularSB42.8IrregularSB53.1CrevasseSB64.5IrregularSB83.3BowlSB94IrregularSB103.1DendriticSB116BowlSB122.3BowlW13.8IrregularW23.8IrregularW33.9LadleW44IrregularW53.8CrevasseW64.5IrregularW73.8BowlW83.5IrregularW92.8IrregularW103.9IrregularW113.9IrregularW122.5IrregularW133.5Irregular339y350100751.053.15n1.053.15n3.7518.75n12.5687.5y10.5252y2.2524.75n22.5450n6.75540y12550250.51.5y14060600.210.63y8040400.888.8y46.7206.71.5614.04n0.724.32y200751000.240.48n8.75306.25y7.5112.5y4.9574.25y2.856n2.25361.0832.40.381.961021.4311.444.627.610503.39.91.472.94251252513650050750240625007507560000250864004005512500750309375050092812.5SeasonPool#Elev.(m)BasinWindbreakSA(m2)Vol. (L),w w W n/a SW n e,s S W ne SW S S n wnw,ene n nwn’s Se,w SW n/an/an/an/a e500020006.713.3067500002100050404109.61808060275751251255025y333.31001000133.30119988y399.913320033.333.30129568n y10025250500102000n n y536.4300172.718.245:50268200y434.318312091.440042995.7y384172124844011289.60(continued)TABLEC.1.(continued)W174.2CrevasseW184.1CrevasseWinter1995D13.4DendriticD23.2IrregularD33.7IrregularD52.8BowlD64.4BowlD75IrregularD84.4CrevasseD93.8IrregularD103.7CrevasseD114CrevasseD123.2BowlD135.5IrregularD143.2CrevasseD156.7DendriticD166.7DendriticD173.9CrevasseD184.6IrregularD195.4IrregularD204.8CrevasseFB12.8BowlFB22.8IrregularFB32.9Bowl1.354.05y1.442.88y2.2533.75nn,e1.224nse1.897.56y3210.783.90.815.67232302.5237.80.5952.98110402402.1210.0630.191.199.520.271.082.732.41.085.4n n y33.416.716.7n y33.416.716.7nSeasonPool#EIev.(m)BasinWindbreakSA(m2)Vol. (L) Cop’diteNauplii#fpoolAutumn94W142.2Bowln2401606020009720(continued)W153.9Crevassee,w1751005025005040W163.9Crevassesw n/a50500n0.281.4n1.68n0.26251.31y0.241.68n42546n2251001256000n/a S se nn,e,w,ss,w wnw,sens S s,es,ew,ew,en,sn’s n n,sn/an/an/a000170100060787.50001893.7800080160n n II n n n n n n n1.85.412540(continued)TABLEC.1. (continued)SeasonPool#EIev.(m)BasinWindbreakSA(m2)Vol.(L)T.caL?#/LMaleFemaleOvig.Fem. Cop’diteNauplii#/poolWinter1995FB42.9Bowlsw2120n(continued)FB52.9Irregularn/a3.7515nFB63.5Irregularn1.311.7nFB73.1Crevassen/a1.085.4nFB82.9Irregularne1.358.1nFB93.2Irregularn/a28y252500002000FB103.2Dendriticnw2.3811.9y5025250005950FB113.2Dendriticne10.843.2nFB122.6Irregularn/a0.40.8nFB132.6Irregularn/a0.20.6nFB142.6Irregularn/a1.715.13nFB151.5Crevasses1.22.4nH14.4Dendriticn,w3.366.72y466.766.783.3133.3116.766.731362.2H23.5Crescentsw4.246.2nH33.9Crescentn/a19y4002020003600H44.1Crevassen,sw3.1528.35y366.7100116.75066.733.3103959H53.8Irreg./Dene1.68.11.76nH62.5Bowlse0.917.28nH72.7Irregulars660nH83.9Ladles0.714nH95Bowl,Jrn0.483.84y6020040002304H104.5Irregularn1.3314.63nH114.1Irregularn0.912.73nH123.3Bowlsw1.9519.5nH133.8Dendriticn/a3.517.5nH145.2Dendriticn,e,w3.3616.8nH154.7Irregularn,s0.885.28nH164.4Irregularn1.266.3y10025075006300(continued)TABLEC.1. (continued)SeasonPool#Elev.(m)BasinWindbreakSA(m2)Vol.(L) Cop’diteNauplii#!poolWinter1995Fl174.7Irregulare,sw4.572n(continued)H184.7Bowln.w1.713.6nH192.9Bowl?w1.1210.08y1751007500017640I-I204.9Dendritice3.6421.84y10020202040021840SB12.9Irregularsw321600nSB22.9Irregularn16480nSB34Irregulare,s2.226.4nSB42.8Irregulars30450nSB53.1Crevassew4320nSB64.5Irregularne0.883.52y80402020002816SB64.5Irregularne3.2597.5nSB83.3Bowlsw0.721.44nSB94Irregulars0.8456.76nSB103.1Dendritics2.5215.12nSB116Bowln0.632.52nW12.5Irregularne10.5399nW23.8Irregularne1.632nW33.9Ladlen2.448nW44Irregularnw7.5172.5nW53.8Crevassen,s218nW64.5Irregulars0.541.62nW73.8Bowle,w1.2546.25nW83.5Irregularsw2.7669nW92.8Irregularnia4.212.6y18040600206022680W103.9Irregularn/a1.9811.88y2440420240900300580289872W113.9Irregularn/a1484y2500250021000W122.5Irregularn/a4.5613.68y75255000010260W133.5Irregulare1.12.2y12005002753001002526400W142.2Bowln0.391.95n(continued)TABLEC.1.(continued)Winter95W153.9Crevassee,w(continued)W163.9CrevasseswW174.2Crevassen,eW184.1Crevassese1.87.2n3.528n0.8128.35n1.266.3nSpring1995D134DendriticD23.2IrregularD33.7IrregularD43.9CrevasseD52.8BowlD64.4BowlD75IrregularD84.4CrevasseD93.8IrregularD103.7CrevasseD114CrevasseD123.2BowlD135.5IrregularD143.2CrevasseD156.7DendriticD166.7DendriticD173.9CrevasseD184.6IrregularD195.4IrregularD204.8CrevasseFB12.8BowlFB22.8Bowl0.352.8n22.5225n1.722.1n0.562.240.21.417.587.5n12.5125y33.333.300.280.84y133.4001.2510y233.31001000.27162y566.7167166.70.686.12n5.29158.72.25123.751714.32457i885.71186.2850100100105000041625066.766.71120.5633.300233300100133.39180.54SeasonPool#EIev.(m)BasinWindbreakSA(m2)Vol. (L)’diteNauplii#/pool1040n0.120.24n2.2513.5n00120.01y988629431885.70.10.3y35050500.241.2n161442.416.80.916.37n/an/a S se se nn,e,w,ss,w wne,swn’s S s,es,ew,ew,en,sn,s n n’sn/an/ay358016401040y266.766.766.7y33.333.3040044060515520033.366.733.344805.60002121.21y315013501000y15000450350150007056002100(continued)TABLEC.1.(continued)SeasonPool#EIev.(m)BasinWindbreakSA(m2)Vol. (L) Cop’diteNauplii#/pool•Spring95FB113.2Dendritic(continued)FB122.6IrregularFB132.6IrregularFB142.6IrregularFB152.2IrregularH14.4DendriticH23.5CrescentII33.9CrescentH44.1CrevasseH53.8Irreg.fDenH62.5BowlH72.7IrregularH83.9LadleH95Bowl,IrH104.5IrregularH114.1IrregularH123.3BowlH133.4Irregular1-1145.2DendriticH154.7IrregularH164.4IrregularH174.7IrregularH184.7BowlH192.9Bowl?H204.9DendriticSB12.9IrregularSB22.9IrregularSB34IrregularSB42.8Irregulars0.7n0.35n0.42n0.225sw0.66n/a0y1200700300y200100100y800400300n n y1400600133.3y1267533200y2200500800y3300800900y1267267400y450150100y2886914771.4y333.420066.7y533.320066.7y533.413366.7y20066.7133.3y1005050y7000200y27501350650y800150150y930016001200y70015010002000936000000420100003360333.3200133.3132291316.7•20016.71140033003003003520040080040019800066.7533.301418750015015750142.9942.9114.364930.566.7005834.5133.30133.311199.366.720066.73600.4500013500000396100200200151.26001500264001502001505120100050005001264815020010056700133.333.3057177.1ne1378n/a0.1050.21n/a0.420.42n/a0.982.94S0.280.56n,w3.159.45sw1.59n/a0.41.6n.sw16e0.561.12se0.53.5s0.752.25 9.8n1.75 2.1 0.6810.56n0nn,e,wn’s ne,swn’w w n/a SW2.250.1320.02160.240.160.0682.76.75 8.19360nn10.5262.5ne,s1.3217.16y333.213333.3S20300n(continued)TABLEC.!.(continued)w,n21231n/a0.280.56e,w1.47wSeasonPool#Elev.(m)BasinWindbreakSA(m2)Vol.(L)tcal.?#/LMaleFemaleOvig.1?em. Cop’diteNaupili#/poolSpring95SB5(continued)SB6SB8SB9SB10SB11Spring95Wi(continued)W2W3W4W5W6WiW8W9W10Wi’W12W13W14W15W16W17W18Summer1995D14400nne0.351.05nSw0.160.32ys0.995.94ns0.060.18y110.0090ynw,e2.856nne3.636n112.133.6nnw1.0812.96yn,s0.635.04ys0.420.42ye,w0.2434.13y•sw3.2435.64nn/a1.120driedn/a0.632.52yn/a3.4120.46yn/a3.1Crevasse4.5Irregular3.3Bowl4Irregular3.1Dendritic6Bowl3.8Irregular3.8Irregular3.9Ladle4Irregular3.8Crevasse4.5Irregular3.8Bowl3.5Irregular2.8Irregular3.9Irregular3.9Irregular2.5Irregular3.5Irregular2.2Bowl3.9Crevasse3.9Crevasse4.2Crevasse4.1Crevasse400200200966.6433266.740040002160880640375001700140060040020001006800220028001400600200e n e,w0000dried0.080.240000012802:33.333.301739.880001816040080279936145060001890000266.7133.358800100082621400400017136020020020028644000070200250150100162000045500Sw00n,e0.7811.7se0.0450.093.4DendriticD23.2IrregularD33.7Irregulardriedy600400200y1800850450n n y650350300(continued)TABLECl.(continued)Summer95D43.9Crevassee,w(continued)D52.8BowlseD64.4BowlnD75Irregularn,e,w,sD84.4Crevasses,wD93.8IrregularwD103.7Crevassene,swD114Crevassen,sD123.2Bowle,sD156.7Dendriticw,eD166.7Dendriticw,eD173.9Crevassen,sD184.6Irregularn,sD195.4IrregularnD204.8Crevassen,sFB12.8BowlnJaFB22.8Bowln/aFB32.9Bowln/aFB42.9BowlswFB63.5IrregularnFB73.1Crevassen/aFB82.9IrregularneFB93.2Irregularn/aFB103.2DendriticnwFB113.2DendriticneFB163.2Irregularn/aH14.4Dendriticn,wH23.5Crescentsw0.1950.59n0.241.2y0.242.88n14.4216n1.75512.29n0.773.08y0.362.52y31.5252y1.524y5.5121n2.5235.28n0.280.84y1.0811.88y0.150.75n2.341170.542. Cop’ditëNauplii#/pool1000048000.421.685.7511.512.2524.59.62884002001005050040015025030020010010050045020015040015050y300500y1800650700y300100150y15010050n y950500250y450250200y350250100y35015050y785026001650y1800800550y900500200n n50 200150150 50 0 50 0 0 02900 40010050 150 0 0 0 0 0 50 450 50 050504015020700007350004320001502052002700058801008190250502400237600100122850I.(continued)TABLEC.1.(continued)SeasonPool#Jflev.(m)BasinWindbreakSA(m2)Vol.(L) Cop’diteNauplil#/poolSummer95II33.9CrescentnJa0.482.4n(continued)H44.1Crevassen,sw1268.82nH53.8Irreg.IDene1.027.14nH62.5Bowlse0.43.2nH72.7Irregulars5.2521y15010050000315001183.9Ladles0.65117nH95Bowl,Irn0.280.84nH104.5Irregularn0.845.04nH114.1Irregularn0.845.04nH123.3Bowlsw0.8810.56y125065040020000132000H145.2Dendriticn,e,wL475.88nH184.7Bowln,w0.320.96nH192.9Bowl?w0.060.12nH204.9Dendriticn/a26nSB12.9Irregularsw9.6384nSB22.9Irregularn10.15253.75nSB34Irregulare,s1.3215.84y650200200200500102960SB42.8Irregulars20340nSB53.1Crevassew3.51386.1nSB64.5Irregularne0.240.24nSB73Ladlene1.656nSB83.3Bowlsw0.20.4y100020020010005004000SB94Irregulars1.086.48nSB103.1Dendritics0.060.24y13506504002505003240W13.8Irregularnw,e2.4561.25nW23.8Irregularne5.0465.52nW33.9Ladlen3.6929.52n(continued)00TABLEC.1. (continued)SeasonPool#Elev.(m)BasinWindbreakSA(m2)Vol. (L) Cop’diteNaupili#IpoolSummer95W53.8Crevassen,s1.2812.8y100505000012800(continued)W64.5Irregulars0.30.6y4002002000002400W73:8Bowle,w0.3156.62y1700950500200500112455W92.8Irregularn/a0.350.7nW103.9Irregularn/a1.125.6y0000000W113.9Irregularn/a3.7826.46y55015010010015050145530W133.5Irregulare2.162.16nW142.2Bowln0.120.12nW174.2Crevassen,e0.7210.8y105015040015050300113400W184.1Crevassese2.6431.68nAppendix C: Supplemental Data 200TABLE C.2. Summary of avian specimens examined. All specimens were examined inOctober and November, 1995, at the National Museum of Natural History, SmithsonianInstitution, Washington, D.C. All specimens were in the form of dried skins stretchedover a cotton body form. Prior to Ca. 1960, skins were typically poisoned with arsenic (P.Auger, pers. comm.); specimens are also sometimes washed in Ivory Snow ® or a similardetergent, then wrapped in sawdust. However, the precise preparation method used formost specimens was not specified.SPECIMEN NMNH TAG # COLLECTION REMARKSGenus HaemotopusH bachrnani male 157982 1897USDA Biol. Survey Granville. WAH. bachmani male 166799 June 24, 1900USDA Biol. Survey British ColumbiaH. bachinani male 366610 May 16, 1936USD1 Biol. Survey Shunagin IslandH. bachmani male 366612 June 22, 1937USD1 Biol. Survey Little Kiska, AleutianIslandsH. bachniani male 157980 June 21, 1897USDA Biol. Survey Lapush, WAH. bachmani male 588899 April 21, 1922USD1 Biol. SurveyH. bachrnani male 157983 September 15, 1897USDA Biol, Survey Destruction IslandH bachrnanifernale 61185 March 8, 1959Smithsonian Puget Sound, WAH. bachmani female 157984 May 20, 1897USDA Biol. SurveyH. bach,nani female 414655 August 13, 1909Smithsonian Coll’nsH. bachmani female 20337 August 14, 1905USDA Biol. Survey San Geronimo IslandH bachmani female 4625 San Miguel Island, CASmithsonianH. bachmani female 70650 St. Martins Island, CASmithsonianH. bachmani female 588900 April 27, 1922USD1 Biol. Survey Cannon Beach, OR(continued)Appendix C: Supplemental Data 201TABLE C.2. (continued)SPECIMEN NMNEI TAG # COLLECTION REMARKSGenus LarusL. californicus male 573002 November 15, 1974 Avitrol poisoningUSD1 Biol. Survey Mather AFB, CAL. californicus male 102867 November 24, 1884Ventura, CAL. californicus male 183618 September 15, 1901USDA Biol. Survey Mono Lake, CAL. californicus male 203352 February 14, 1906USDA Biol. Survey Lapaz Bay, MexicoL. californicus male 589438 September 3, 1933 Unidentified crustaceaUSDA Biol. Survey Muitnoma Island, ORL. californicus male 261469 October 7, 1915USDA Biol. Survey Lake Bowdoin, MTL. cahfornicus male 582796 April 14, 1984 510 gMono Lake, CA Isopoda?L. californicus male 168596 July 13, 1901Great Slave LakeL. californicus male 236797 February 20, 1915Wilmington, CAL. californicus female 4509 (no date) specimen in very goodUSNM Shoalwater Bay, WA conditionL. caIijrnicus female 557578 August 22, 1982Samoa Peninsula, CAL. californicus female 197421 December 15, 1985USNM Humbolt Bay, CAL. californicus female 589437 December 12, 1930Gold BeachL. californicus female 158042 September 20, 1897USDA Biol. Survey Oyhut, WAL. cahfornicus female 582804 April 30, 1984Mono Co., CAL. californicus female 206156 November 5, 1908USDA Biol. Survey Great Slave LakeL, californicusfernale 589434 May29, 1934USD1 Biol. Survey Clear Lake, CAAppendix C: Supplemental Data 202TABLE C.3. Pearson Product Moment Correlation of Tigriopus calfornicus life-historystage vs. density, temperature, salinity, and tidal elevation. r = Pearson (rank) correlationcoefficient; P = probability value; n = sample size; (not tested) denotes reciprocal of otherpairwise comparisons. For pairwise comparisons with P values less than 0.05, positive ornegative correlations are suggested by bold type and positive or negative r values,respectively. For pairwise values with a P value greater than 0.05, no significantcorrelation exists. Source: Jandel, 1994.Nauplii vs.Adult Adult OvigerousMales Females Female Copepoditesr 0.0137 0.0132 0.0759 (not tested)P 0.7690 0.7772 0.1028n 463 463 463Density/L Temperature Salinity Elevationr 0.0645 -0.0749 -0.0682 0.0605P 0.1660 0.1074 0.1426 0.1982n 463 463 463 454Adult Adult OvigerousCopepodites vs. Males Females Females Nauplilr 4.77E-001 8.50E-001 4.89E-001 0.0302P 1.39 E -027 6.29 E -130 4.23 E -029 0,5177n 462 462 462 462DensityfL Temperature Salinity Elevationr 6.95 E-001 0.0373 0.0138 0.0630P 8.81E-068 0.4238 0.7672 0.1807n 462 462 462 453OvigerousFemales vs.Adult AdultMales Females Copepodites Naupliir 0.9800 7.38 E -001 (not tested) (not tested)P 0.0000 1.21E-080n 463 463Density/L Temperature Salinity Elevationr 9.54 E-001 -0.0002-0.0168 0.0693P 8.47E-244 0.9971 0.7178 0.1403n 463 463 463 454(continued)Appendix C: Supplemental Data 203TABLE C.3. (continued)Adult Adult OvigerousFemales vs. Males Females Copepodites Naupliir 0.7680 (not tested) (not tested) (not tested)P 2.186E-091n 463Density/L Temperature Salinity Elevationr 0.8990 0.0424 0.0166 0.0253P 1.07E-167 0.3628 0.7210 0.5911n 463 463 463 454Adult Adult OvigerousMales vs. Females Females Copepodites Naupliir (not tested) (not tested) (not tested) (not tested)PnDensity/L Temperature Salinity Elevationr 9.60E-001 0.0212-0.0031 0.0494P 1.66 E-257 0.6487 0.9471 0.2940n 463 463 463 454DensityIL vs. Temperature Salinity Elevationr 0.0225-0.0024 0.0539P 0.6298 0.95889 0.2518n 463 463 454Appendix C. Supplemental Data 204TABLE C.4. Spearman Rank Order correlation of elevation, temperature, salinity, andpopulation density vs. Tigriopus californicus life-history stage. rs = Spearman correlationcoefficient; P = probability value; n = sample size; (not tested) denotes reciprocal of otherpairwise comparisons. For pairwise comparisons with P values less than 005, positive ornegative correlations are suggested by bold type and positive or negative rs values,respectively. For pairwise values with a P value greater than 0.05, no significantcorrelation exists. Source: Jandel, 1994.Adult Adult OvigerousElevation vs. Males Females Females Copepodites-0.0100 -0.0126 0.0882 -0.0353P 0.83 12 0.7891 0.0605 0.4540n 454 454 454 453Nauplii Temperature Salinity . DensitylLrs -0.0129 -0.1600 0.0970 -0.0415P 0.7847 0.0000 0.0389 0.3780n 454 454 463 454Adult Adult OvigerousTemperature vs. Males Females Females Copepoditesrs 0.0821 0.0576 0.0595 0,0472P 0.0778 0.2163 0.2011 0.3113n 463 463 463 463Nauplii Salinity DensityfLrs -0.0253 0.5000 0.0846P 0.5865 0.0000 0.0688n 463 463 463Adult Adult OvigerousSalinity vs. Males Females Females Copepoditesrs 0.0625 0.043 1 0.0493 -0.0093P 0. 1792 0.3549 0.2897 0.8418n 463 463 463 462Nauplil Temperature DensitylLrs -0.1600 (not tested) 0.0339P 0.0000 0.4661n 463 463(continued)Appendix C: Supplemental Data 205TABLE C.4. (continued)Adult Adult OvigerousDensityfL vs. Males Females Females Copepoditesrs 0.9500 0.9200 0.7500 0.7100P 0.0000 0.0000 0.0000 0.0000n 463 463 463 463Nauplil Temperature Salinityrs 0.2800 (not tested) (not tested)P 0.0000n 463Adult Adult OvigerousMales vs. Females Females Copepodites Naupilirs 0.9400 0.7300 (not tested) (not tested)P 0.0000 0.0000n 463 463Adult Adult OvigerousFemales vs. Males Females Copepodites Naupliirs (not tested) 0.6900 0.6600 0.1183P 0.0000 0.6000 0.0109n 463 462 463Appendix C: Supplemental Data 206TABLE C.5. Spearman Rank Order correlation of TigrEopus cahfornicus life-history stagepairwise comparisons. rs = Spearman correlation coefficient; P = probability value; n =sample size; (not tested) denotes reciprocal of other pairwise comparisons. For pairwisecomparisons with P values less than 0.05, positive or negative correlations are suggestedby bold type and positive or negative rs values, respectively. For pairwise values with a Pvalue greater than 0.05, no significant correlation exists. Source: Jandel, 1994.Adult Adult OvigeronsNauplii vs. Males Females Females Copepoditesrs 0.1233 0.1183 0.1471 0.2300P 0.0079 0.0109 0.0015 0.0000n 463 463 463 462DensityfL Elevationrs 0.2800 -0.0129P 0.0000 0.7847n 463 454Adult Adult OvigerousCopepodites vs. Males Females Females Naupliirs 0.6500 0.6600 0.4900 0.2300P 0.0000 0.0000 0.0000 0.0000n 462 462 462 462PoolNauplii Deusity/L Elevationrs 0.2300 0.7100 -0.0353P 0.0000 0.0000 0.4540n 462 462 453Ovigerous Adult AdultFemales vs. Males Females Copepodites Naupliirs 0.7300 0.6900 0.4900 (not tested)P 0.0000 0.0000 0.0000n 463 463 462PoolDensity/L Elevationrs 0.7500 0.0882P 0.0000 0.0605n 454 454Adult Ovigerous PoolFemales vs. Males Females DensityfL Elevationrs 0.9400 (not tested) 0.9200 -0.0126P 0.0000 0.0000 0.7891n 463 463 454Appendix C. Supplemental Data 207TABLE C.6. Two-way Analysis of Variance of Tigriopus californicus abundance with seasonand site location. Given the incidence of zero values in the data set, copepod abundance wastransformed by log +l. Power oftest at x 0.05 is 0.979 for season and 0.879 for location.NB: Abundance data failed tests for normality and homogeneity of variance (p <0.0001 in both instances).Source: Jandel, 1994.Source of Variance DF SS MSSeason 4 33.0 8.25Location 4 23.9 5.97Residual 454 592.0 1.30Total 462 651.5 1.41Source of Variance F PSeason 6.32 <0.0001Location 4.58 0.0012Least square means for SeasonGroup Mean Std. ErrorSpring 1994 1.013 0.254Summer 1994 0.691 0.255Autumn 1994 1.015 0.256Winter 1994 1.425 0.273Winter 1995 0.887 0.276Least square means for LocationGroup Mean Std. ErrorDiana Island 1.015 0.256First Beach 1.425 0.273Helby Island 0.69 1 0.255Second Beach 0.887 0.276Wizard Islet 1.013 0.254Appendix C: Supplemental Data 208TABLE C7. Student-Newman-Keuls multiple comparisons for seasonal Tigriopus cahfornicusabundance. Source: Jandel, 1994.Comparison A means p qAutumn vs. Winter 1.407 5 1.715Autumn vs. Winter 0.697 4 6.795Autumn vs. Spring 0.301 3 2.016Autumn vs. Sununer 0.198 2 2.106Summer vs. Winter 1994 1.209 4 1.475Summer vs. Winter 1995 0.498 3 5.089Summervs. Spring 0.102 2 0.692Springvs. Winter 1994 1.107 3 1.333Spring vs. Winter 1995 0.396 2 2.588Winter 1994 vs. Winter 1995 0.711 2 0.866P <0.05Autumn vs. Winter 1994 No(remainder not tested)Appendix C: Supplemental Data 209TABLE C.8. Student-Newman-Keuls multiple comparisons for locational Tigriopus calfornicusabundance. Source: Jandel, 1994.Comparison A means p qFirst Beach vs. Helby Island 0.73347 5 5.9444First Beach vs. Second Beach 0.53818 4 3.2633First Beach vs. Wizard Islet 0.41148 3 3.3076First Beach vs. Diana Island 0.40967 2 3.2777Diana Island vs. Helby Island 0.3238 4 3.0436Diana Island vs. Second Beach 0.1285 3 0.8365Diana Island vs. Wizard Islet 0.00 181 2 0.0 170Wizard Islet vs. Helby Islet 0.32 199 3 3.0777Wizard Islet vs. Second Beach 0.12669 2 0.8300Second Beach vs. Helby Island 0.19530 2 1.2785P < 0.05First Beach vs. Helby Island YesFirst Beach vs. Second Beach NoDiana Island vs. Helby Island Nb(remainder not tested)Appendix C: Supplemental Data 210TABLE C.9. Temperature and salinity replicate measures. Triplicate measuresfor pooi temperature (°C) and salinity (°I) readings for Barkley Sound poolsin January, 1995. D = Diana Island; FB = First Beach; H = Helby Island; W =Wizard Islet.Rep 1 Rep 2 Rep 3 Avg SDPool Temp Salinity Temp Salinity Temp Salinity Temp Salinity Temp SalinityDl 10 25.3 9 28.5 9 28,2 9.3 27.3 0.6 1.8D1O 9 30.7 9 27.1 9 30.0 9 29.3 0 1.9Dli 10 31.1 9 30.1 9 30.3 9,3 30.5 0.6 0.5D12 9 27.6 8 26.1 8 29.5 8.3 27.7 0.6 1.7D13 9 29.4 8 20.9 8 28.1 8.3 26.1 0.6 4.6D14 10 29.0 8 28.5 9 27.7 9 28.4 1 0.7D15 9 27.0 9 28.7 8 27.7 8.7 27.8 0.6 0.9D16 9 27.0 9 27.4 8 28.9 8.7 27.8 0.6 1.0D17 9 30.7 10 28.9 9 16.0 9.3 25.2 0.6 8.0D18 10 32.0 9 29.8 9 28.4 9.3 30.1 0.6 1.8D19 9 30.8 9 28.6 9 28.8 9 29.4 0 1.2D2 9 25.2 8 12.5 8 12.0 8.3 16.6 0.6 7.5D20 9 31.8 9 28.6 9 28.6 9 29.7 0 1.9D3 9 23.9 8 25.0 8 27.7 8.3 25.5 0.6 2.0D4 8 28.0 9 6.6 8 8.0 8,3 14.2 0.6 12.0D5 9 24.0 9 23.2 9 25.0 9 24.1 0 . 0.9D6 10 23.5 10 23.4 10 26.8 10 24.6 0 1.9D7 8 30.8 10 30.4 9 29.4 9 30.2 1 0.7D8 9 27.7 9 23.2 9 23.8 9 24.9 0 2.4D9 9 31.6 10 29.9 9 30.0 9.3 30.5 0.6 1.0FBi 14 29.5 10 28.8 12 28.3 12 28.9 2 0.6FBIO 10 29.8 9 27.4 10 24.5 9.7 27.2 0.6 2.7FB11 9 30.9 10 28.4 10 29.2 9.7 29.5 0.6 1.3FB12 9 27.3 12 26.5 14 24.2 11.7 26.0 2.5 1.6FB13 10 28.9 10 27.0 14 26.9 11.3 27.6 2.3 1.1FB14 14 28.2 9 28.6 10 26.4 11 27.7 2.6 1.2FB15 12 28.2 8 28.3 9 28.3 9.7 28.3 2.1 0.1FB2 11 29.1 9 29.2 12 26.1 10.7 28.1 1.5 1.8FB3 12 29.7 12 28.9 12 29.6 12 29.4 0 0.4FB4 11 30.4 9 29.8 14 28.9 11.3 29.7 2.5 0.8FB5 9 29.8 9 29.6 9 29.4 9 29.6 0 0.2FB6 9 29.5 9 28.9 10 29.1 9.3 29.2 0.6 0.3FB7 11 29.3 9 29.2 9 28.4 9.7 29.0 1.2 0.5FB8 10 29.2 9 28.4 10 29.4 9.7 29.0 0.6 0.5FB9 9 29.7 9 28.6 9 28.1 9 28.8 0 0.8(continued)Appendix C: Supplemental Data 211TABLE C.9. (continued)Rep 1 Rep 2 Rep 3 Avg SDPool Temp Salinity Temp Salinity Temp Salinity Temp Salinity Temp SalinityHi 9 11.3 11 6.3 10 5.4 10 7.7 1 3.2H10 10 16.6 11 13.4 9 13,7 10 14.6 1 1.8H11 10 16.2 10 13.5 11 14.2 10.3 14.6 0.6 1.4H12 8 16.9 11 12.6 10 13.2 9.7 14.2 1.5 2.3H13 10 27.7 11 14.5 10 14.3 10.3 18.8 0.6 7.7H14 10 16.5 9 7.6 11 6.5 10 10.2 1 5.5HiS 11 53.1 11 12.0 10 12.1 10.7 25.7 0.6 23.7H16 11 27.5 10 11.2 10 11.7 10.3 16.8 0.6 9.3H17 10 9.6 11 12.7 10 11.0 10.3 11.1 0.6 1.6H18 11 4.8 10 3.1 10 2.5 10.3 3.5 0.6 1.2H19 11 10.8 11 6.9 10 5.6 10.7 7.8 0.6 2.7H2 10 19.6 11 6.5 11 5.5 10.7 10.5 0.6 7.9H20 12 11.0 10 6.6 11 5.5 11 7.7 1 2.9H3 10 10.2 10 5.9 11 5.4 10.3 7.2 0.6 2.6H4 10 9.8 10 6.5 11 5.9 10.3 7.4 0.6 2.1H5 11 9.7 11 5.8 11 5.9 11 7.1 0 2.2H6 10 26.3 9 14.6 11 13.5 10 18.1 1 7.1H7 7 25.4 11 12.4 10 12.9 9.3 16.9 2.1 7.4H8 10 26.3 10 13.8 8 13.1 9.3 17.7 1.2 7.4H9 10 16.2 11 13.3 10 13.4 10.3 14.3 0.6 1.7Wi 9 19.7 9 3.0 10 4.0 9.3 8.9 0.6 9.4W10 9 12.6 9 13.5 10 14.7 9.3 13.6 0.6 1.1Wil 8 9.2 8 14.5 8 12.9 8 12.2 0 2.7W12 9 12.8 9 13.9 8 14.8 8.7 13.8 0.6 1.0W13 11 9.8 9 10.7 8 11.6 9.3 10.7 1.5 0.9W14 9 6.3 9 7.8 9 7.8 9 7.3 0 0.9W15 9 8.9 8 9.1 8 8.2 8.3 8.7 0.6 0.5W16 10 18.3 9 3.3 8 4.8 9 8.8 1 8.3W17 9 53.6 9 3.4 9 5.3 9 20.8 0 28.5W18 10 3.6 10 3.9 9 6.3 9.7 4.6 0.6 1.5W2 9 17.1 8 3.0 10 4.4 9 8.2 1 7.8W3 10 3.6 10 3.6 8 6.6 9.3 4.6 1.2 1.7W4 8 17.6 9 3.3 9 4.9 8.7 8.6 0.6 7.8W5 10 24.1 9 3.6 8 5.6 9 11.1 1 11.3W6 9 5.4 10 3.4 9 5.7 9.3 4.8 0.6 1.3W7 9 6.9 9 3.5 9 5.8 9 5.4 0 1.7W8 9 3.5 10 3.8 9 6.2 9.3 4.5 0.6 1.5W9 9 12.6 9 17.3 9 18.4 9 16.1 0 3.1Appendix C: Supplemental Data 212Figure C.2. 10-Minute Splashpool Temperatureand Salinity Flux - Friday Harbor• ThMP. (oC)20- - SALINITY (aloo)15 : 9.: :‘‘:• • • • • • • :0 I I I I I I I I I I I I I I I I I I I I I I1 2 3 4HOURS (Sampling at 10-minute intervals)FrnuI C.2. Ten-minute splashpool temperature and salinity flux at Friday Harbor.Summaiy of temperature and salinity thplicate measurements taken each 10 minutes fromone randomly selected pool at the Friday Harbor, Washington, study site (see Figure A.6)using the methods of Chapter 1. For clarity, error bars are not plotted.Appendix C: Supplemental Data 213FIGURE C.3. Ten-minute splashpool temperature and salinity flux at Cattle Point.Summary of temperature and salinity triplicate measurements taken each 10 minutes fromone randomly selected pooi at the Cattle Point, Washington, study site (see Figure A.6).For clarity, error bars are not plotted.Figure C.3. 10-Minute Splashpool Temperatureand Salinity Flux- Cattle Pointm20181161412•-:‘ 10. 820• ThMP. (oC)•.. • . SALINITY (Woo)0 1 2 3 4 5 6 7HOURS (Sampling at 10-minute Intervals)Appendix C: Supplemental Data 214FIGURE C.4. Six-hour splashpool temperature and salinity flux at Friday Harbor.Summary of temperature and salinity triplicate measurements taken each 6 hours from onerandomly selected pooi at the Friday Harbor, Washington, study site (see Figure A.6). Forclarity, error bars are not plotted.2016Figure C.4. 6-Hour Splashpool Temperatureand Salinity Flux - Friday HarborU• TEMP. (oC)-. U - SALINITY (Woo)0.E8400 1 2 3 4 5 6 7DAYS (Sampling at 6 hour Intervals)Appendix C: Supplemental Data 215FIGURE C.5. Six-hour splashpool temperature and salinity flux at Cattle Point. Summaryof temperature and salinity triplicate measurements taken each 6 hours from one, randomlyselected pool at the Cattle Point, Washington, study site (see Figure A.6). For clarity,error bars are not plotted.12Figure C.5. 6-Hour Splashpool Temperatureand Salinity Flux - Cattle Point.— 10E6• ThMP. (oC)--. - SALINITY (o/oo)4200 1 2 3 4 5 6 7DAYS (Sampling at 6-hour Intervals)Appendix C: Supplemental Data 216FIGURE C.6. Hourly splashpool temperature and salinity flux at Friday Harbor. Summaryof temperature and salinity triplicate measurements taken each 30 minutes from one,randomly selected pool at the Friday Harbor, Washington, study site (see Figure A.6). Forclarity, error bars are not plotted.30Figure C.6. Hourly Splashpool Temperatureand Salinity Flux - Friday Harbor2520I• SIIIrdI1510• TEMP. (oC)-. - SALINiTY (ciloo)S500 1 2 3 4HOURS (Sampling at 30-minute Intervals)5 6 7Appendix C: Supplemental Data 217FIGURE C.7. Hourly splashpool temperature and salinity flux at Cattle Point Summaryof temperature and salinity triplicate measurements taken each 30 minutes from one,randomly selected pool at the Cattle Point, Washington, study site (see Figure A.6). Forclarity, error bars are not plotted.Figure C.7. Hourly Splashpool Temperatureand Salinity Flux - Cattle Point8765S--II232I• ThMP. (cC)-. - SALINFFY (a/cc)0 1 2 3 4 5 6 7HOURS (Sampling at 30-minute Intervals)Appendix C: Supplemental Data 218Figure C.8. 12-Hour Splashpool Temperatureand Salinfty Flux - Cattle Point30s : :8: j__20 : • TEMP.(oC)“SALINITY(o1oo)‘15I.10DAYS (Sampling at 12-hour intervals)FIGURE C.8. Twelve-hour splashpool temperature and salinity flux at Cattle PointSummary of temperature and salinity triplicate measurements taken each 12-hoursfromone, randomly selected pooi at the Cattle Point, Washington, study site (see Figure A.6).For clarity, error bars are not plotted.


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