UBC Theses and Dissertations
Ecology of Tigriopus californicus (Copepoda, Harpacticoida) in Barkley Sound, British Columbia Powlik, James John
The thesis addresses several aspects of the habitat characters and population attributes of the splashpool copepod, Tigriopus californicus (Baker) in Barkley Sound, British Columbia. Overall, 90.1% of pools containing T. californicus were found at 3.0 to 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 1 to 139%; hydrogen ion concentrations (pH) of 6.1 to 9.5; and oxygen levels of 1.1 to 13.7 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 macroalgae including Enteromorpha compressa, Scytosiphon lomentaria and its Ralfsia-lilce alternate phase. Incidental invertebrates and vertebrates that may act as potential agents of dispersal for T. californicus and its congeners are also listed and discussed relative to the world-wide biogeography of the genus. In an analysis of the copepod’s association with chlorophytic macroalgae, pools and laboratory microcosms containing the alga Cladophora trichotoma retained fewer surviving 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 the establishment of copepod populations. In a second experiment, apparently dead Tigriopus cahfornicus were enlivened following re-hydration with either fresh or sea water, with gravid females and adult males demonstrating the greatest response (10.7 ± 8.5% recovery overall). Development and body length were also compared under conditions representative of 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 in culture; field specimens had a mean clutch size of 23 ± 6.5 eggs in winter (January), increasing to 37 ± 10.2 eggs • clutch⁻¹ in summer (July and August). Population density ranged from 217 ± 401.7 individuals • L⁻¹ in winter to 835 ± 1750.6 individuals • L⁻¹ in summer, exceeding 20,000 individuals L⁻¹ in some pools. A synthesis of these results with previous studies is provided, including suggested parameters for estimating population flux.
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