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Allocation of blade surface area to meiospore production in annual and perennial representatives of the… Klinger, Terrie 1985

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ALLOCATION  OF B L A D E  SURFACE  AREA  TO M E I O S P O R E P R O D U C T I O N I N A N N U A L AND OF THE  PERENNIAL GENUS  REPRESENTATIVES  LAMINARIA  By TERRIE A.B.,  University  of California,  A T H E S I S SUBMITTED THE  KLINGER B e r k e l e y , 1979  IN PARTIAL FULFILLMENT  R E Q U I R E M E N T S FOR M A S T E R OF  THE  DEGREE  OF  SCIENCE  in THE F A C U L T Y  OF GRADUATE  DEPARTMENT OF  We  accept this to  THE  BOTANY  thesis  the required  STUDIES  as  conforming  standard  U N I V E R S I T Y OF B R I T I S H October ©  Terrie  COLUMBIA  1984  Klinger  1984  OF  In p r e s e n t i n g  t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of  requirements f o r an advanced degree at the  the  University  o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make it  f r e e l y a v a i l a b l e f o r reference  and  study.  I  further  agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying of t h i s t h e s i s f o r s c h o l a r l y purposes may  be  department or by h i s or her  granted by  the head o f  representatives.  my  It i s  understood t h a t copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain  s h a l l not be  allowed without my  permission.  Department o f The U n i v e r s i t y o f B r i t i s h 1956 Main Mall Vancouver, Canada V6T 1Y3  -6  (3/81)  Columbia  written  ABSTRACT  A l l o c a t i o n of blade for  semelparous  representatives  (Phaeophyta: L a m i n a r i a l e s ) a t each of two s i t e s i n B a r k l e y  Sound,  Vancouver  Island,  ephemera produced  and J u l y ; a maximum  vegetative  area  was  devoted  i n d i v i d u a l s were r e p r o d u c t i v e w i t h i n i t e r o p a r o u s sporophyte L a m i n a r i a  mean to at  percentage  sorus  production,  and  any  These r e s u l t s are  of  production,  least  one  31.7%  of  total  and 100% of the  sample.  The  perennial  s e t c h e l l i i produced s o r i throughout the y e a r ;  a maximum mean percentage of 30.4% of t o t a l blade  sample.  the  annual semelparous sporophyte L a m i n a r i a  s o r i between A p r i l blade  of  quantified Laminaria  The  iteroparous  was genus  B.C.  and  s u r f a c e area t o meiospore p r o d u c t i o n  area was  devoted  to  sorus  a maximum of 54% of the i n d i v i d u a l s were r e p r o d u c t i v e w i t h i n discussed  in  the  context  of  life  history  evolution.  C o n c e n t r i c r i n g s are v i s i b l e setchellii.  These  rings  were  demonstrated  p e r m i t t e d e s t i m a t i o n of i n d i v i d u a l of  L.  setchellii  at  two  sites  d i s s i m i l a r between p o p u l a t i o n s , twelve y e a r  to  age and of age s t r u c t u r e among i n Barkley  and showed  no  age c l a s s e s were most abundant  Sound.  Age  evidence  of  at  Laminaria  form a n n u a l l y , and thereby  age c l a s s was most abundant a t one s i t e  and t h r e e y e a r Bay).  i n c r o s s - s e c t i o n of the s t i p e s of  populations  s t r u c t u r e s were stability.  The  (Wizard Rock), and the two a  second  site  (Execution  - i i i-  TABLE OF CONTENTS page Chapter 1.  General I n t r o d u c t i o n  Chapter 2.  Seasonal P a t t e r n s o f Recruitment i n Laminaria  Chapter 3.  17  M a t e r i a l s and Methods  18  Results  19  Discussion  20  A l l o c a t i o n t o Meiospore P r o d u c t i o n i n ephemera  26  Introduction  26  M a t e r i a l s and Methods  26  Results  29  Discussion  31  A l l o c a t i o n t o Meiospore P r o d u c t i o n i n Laminaria  Chapter 5.  17  Introduction  Laminaria  Chapter 4.  ephemera  1  setchellii  45  Introduction  45  M a t e r i a l s and Methods  45  Results  47  Discussion  51  Age S t r u c t u r e among P o p u l a t i o n s o f Laminaria  setchellii  67  Introduction  67  M a t e r i a l s and Methods  68  Results  69  Discussion  71  - iv -  TABLE OF CONTENTS, cont.  Chapter 6.  General D i s c u s s i o n  80  Bibliography  84  Appendix 1  90  Appendix 2  91  -  v  -  LIST OF TABLES  Page  Table  Title  2.1.  Tagged cobble a t t r i t i o n  3.1.  Sampling  schedule, Laminaria ephemera.  35  4.1.  Sampling  schedule, Laminaria  55  A.l.  R e s u l t s of gametophyte c u l t u r e  rate.  25  setchellii. experiments.  96  -  LIST  Figure  OF  FIGURES  Title  Page  2.1.  Map  3.1.  V e g e t a t i v e and Cable Beach.  3.2.  v i -  of Barkley  Vegetative Execution  Sound, soral  B.C.  24  surface  area, 36  and s o r a l  surface  area,  Bay.  37  3.3.  Percentage  of soral  p l a n t s , Cable  3.4.  Percentage  of soral  plants, Execution  3.5.  Size  class  distribution,  Cable  3.6.  Size  class  distribution,  Execution  3.7.  Size class distribution, p l a n t s , Cable Beach.  reproductive  3.8.  Size class distribution, p l a n t s . E x e c u t i o n Bay.  reproductive  3.9.  4.1.  4.2.  Ratio of soral surface area.  surface  V e g e t a t i v e and W i z a r d Rock.  soral  Ratio of soral surface area.  surface  Bay.  39  Beach.  40  Bay.  41  42 43  area  to vegetative  surface  area, 56  area  to  vegetative 57  Percentage  of soral  4.4.  Vegetative  and  soral  plants, Wizard surfacea  Rock.  58  area,  Bay. of soral  59  4.5.  Percentage  4.6.  Reproductive  plants  versus  age, W i z a r d  4.7.  Reproductive  plants  versus  age, E x e c u t i o n  4.8.  S t i p e volume v e r s u s 05 A u g u s t 1 9 8 2 .  age, Wizard  S t i p e volume v e r s u s 18 N o v e m b e r 19 8 2 .  age, W i z a r d  4.9.  38  44  4.3.  Execution  Beach.  plants, Execution  Bay.  60  Rock. Bay.  61 62  Rock, 63 Rock, 64  - vii-  LIST OF FIGURES,  4.10. 4.11.  cont.  S t i p e volume versus age, E x e c u t i o n Bay, 28 October 1982.  65  S t i p e volume versus age, E x e c u t i o n Bay, 10 November  1982.  66  5.1.  S i z e c l a s s d i s t r i b u t i o n , Wizard Rock.  74  5.2.  Age c l a s s d i s t r i b u t i o n , Wizard Rock, 18 November 1982. Age c l a s s d i s t r i b u t i o n , Wizard Rock,  75  pooled samples.  76  5.4.  S i z e c l a s s d i s t r i b u t i o n , E x e c u t i o n Bay.  77  5.5.  Age c l a s s d i s t r i b u t i o n , E x e c u t i o n Bay, 10 Novmeber 1982. Age c l a s s d i s t r i b u t i o n , E x e c u t i o n Bay, pooled samples.  79  S t i p e c r o s s - s e c t i o n , Laminaria s e t c h e l l i i .  93  5.3.  5.6. A.l.  78  -  v i i i  -  ACKNOWLEDGEMENTS  S i n c e r e thanks are due Dr. R.E. DeWreede f o r h i s encouragement, guidance, and  unflagging  patience  through the c o m p l e t i o n of t h i s p r o j e c t .  a l s o due D r s . P.J. H a r r i s o n and R. comment,  and  for real  Turkington  f o r valuable  expediency i n the c r i t i c a l  discussion  and  review of t h i s t h e s i s .  The  a d m i n i s t r a t i v e e f f o r t s of Dr. K. Cole are g r a t e f u l l y  acknowledged.  Scagel  graciously  and  the  Department  of  l a b o r a t o r y use at B a m f i e l d Marine  Botany,  U.B.C,  Thanks are  Dr.  R.F.  provided f o r  Station.  Thanks t o Dr. L.D. Druehl f o r i n t e r e s t e d d i s c u s s i o n and f o r g e n e r a l  help  with kelp.  Thanks are a l s o extended t o Robin B o a l , K i t t y L l o y d , Ann L i n d w a l l ,  and S h i r l e y  Smith-Pakula.  Dr. R.E. DeWreede, Lynn Y i p , Dr. comprehensive  M.W.  Hawkes  and  a s s i s t a n c e and support i n the s u b t i d a l .  Stuart  Arkett  Additional  and welcome  support i n the f i e l d was p r o v i d e d by John V e r s e n d a a l , Herb Vandermeulen, Villeneuve,  Iddamaria  Germann,  Cabot, Ray Lewis, R i c k S c h u l l e r , Joel  Harry  gave  Serge  Goldberg, Ron Smith, R i c k Cohen, E r i c  Steve F a i n , J o e l E l l i o t ,  Adrienne F o r e s t , and  Pecchioli.  Serge V i l l e n e u v e and Dr. L.D. Druehl k i n d l y loaned the f a c i l i t i e s Institute  f o r the  Enhancement  Emery made a v a i l a b l e the  LSI-11  of the  of P h o t o s y n t h e s i s , B a m f i e l d , B.C.  Dr. Wm.J.  computer  Dept.  and  digitizer  of  the  of  Oceanography, U.B.C.  Thanks t o Iddamaria  Sharon  Germann  and  Rob  DeWreede,  Denise  Bonin  and  Mike  Hawkes,  and U l i Hoeger f o r unending kindness and h o s p i t a l i t y .  thanks t o Lynn Y i p f o r e v e r y t h i n g shared and accomplished  subaerially.  Big  -  1  -  CHAPTER 1 GENERAL  INTRODUCTION  B e n t h i c marine algae e x h i b i t l i f e strongly  from  many of the l i f e  S c i e n t i f i c treatment  been  taxonomic  a  theoretical of  algal  or  of a l g a l  phylogenetic  (but f o r e x c e p t i o n s  life histories nature,  l i f e h i s t o r i e s i n the context  group of  kelps  (order  distributed  rather  has  than q u a n t i t i v e or  Laminariales)  of l i f e  comprise  a  history evolution.  taxonomically  or  initiation  sporophyte  liberates  meiospores  gametophytes.  antheridia;  which  fertilization  i n which  germinate  Gametophytes mature t o  Members the  to  produce  produce  either  i s oogamous, and r e s u l t s i n sporophyte  ( E a i n , 1979, and r e f e r e n c e s t h e r e i n ) .  Sporophytes t y p i c a l l y complexity  are l a r g e and show v a r y i n g degrees of m o r p h o l o g i c a l  ( c f . Setchell  Laminaria  setchellii  Aresch.)  maintain  and  Gardner, 1925).  a  woody  species  (e.g. N e r e o c v s t i s l u e t k e a n a stipes.  B l a d e s may be Blades  Eisenia  (Mert.) Post,  or  multiple,  e t Rupr.) m a i n t a i n  shortened,  and  may  be  or absent  entire  arborea  Macrocystis  g r o e n l a n d i c a Rosenv.), as w e l l as most  S t i p e s may be e l o n g a t e ,  single  Rupr.,  s t i p e ; other p e r e n n i a l s p e c i e s (e.g.  (L.) C. Ag. , L a m i n a r i a  more p l i a n t  Some p e r e n n i a l s p e c i e s ( e . g .  S i l v a , Pterygophora c a l i f o r n i c a  pyrifera  dissected.  well-defined  throughout the n o r t h e r n and southern Hemispheres.  microscopic filamentous oogonia  Evaluation  of p o p u l a t i o n dynamics and r e p r o d u c t i v e  the order e x h i b i t a heteromorphic a l t e r n a t i o n of g e n e r a t i o n s ,  macroscopic  deviate  traditionally  see C l a y t o n , 1982; S e a r l e s , 1980).  s t r a t e g i e s i s t i m e l y and germane t o the study  The  which  h i s t o r y phenomena d e s c r i b e d f o r h i g h e r p l a n t s  and animals. of  history characteristics  annual slender,  entirely.  or  variously  produced by annual s p e c i e s are u s u a l l y m a i n t a i n e d  f o r the  - 2 -  d u r a t i o n of the season, w h i l e b l a d e s produced by many of the p e r e n n i a l (e.g. L a m i n a r i a s e t c h e l l i i ,  species  Pleurophycus g a r d n e r i ) a r e deciduous; t h a t i s , new  b l a d e s are formed a n n u a l l y and remnants of o l d b l a d e s are not r e t a i n e d . growth i s i n d e t e r m i n a t e i n most  species.  Meiosporangia are produced i n (Laminariaceae)  or  Lessoniaceae). divisions  on  From  16  blades  Paraphyses and u l t i m a t e l y  of meristodermal c e l l s  to  sporangial  specialized  and s p o r a n g i a are pigmented 64  sori  on  or  are  reported  sporangium  (Eain,  terminal  sporangia  from  produce  (Eain,  (Eain,  1964).  Members of the genus  thirty-two  spores  per  1979).  The r a t i o of female t o male spores produced per sporangium 1:1  mitotic  Both paraphyses  as are l i b e r a t e d meiospores  consistently  blade  (Alariaceae,  originate  (Walker, 1980; E a i n , 1979).  (ibid.),  to  the  sporophylls  spores may be produced per sporangium.  Laminaria  Blade  1979).  Spores  germinate  within  about  l i b e r a t i o n ( E a i n , 1964); t h e r e i s no evidence t h a t  is  reportedly  twenty-four  spores  remain  hours  of  planktonic  f o r an extended p e r i o d .  N u t r i e n t s are a s s i m i l a t e d a c r o s s the blade s u r f a c e from medium.  Photosynthesis  occurs a l o n g the l e n g t h of the t h a l l u s ,  of carbon f i x a t i o n may vary w i t h d i s t a n c e from the and  Kremer,  1978).  The  capacity  transition  1976;  Schmitz  and  Srivastrava,  translocation i s generally u n i d i r e c t i o n a l , Translocation  towards  surrounding though  zone  rates  (Kuppers  f o r carbohydrate t r a n s l o c a t i o n has been  r e p o r t e d f o r a number of s p e c i e s (Lobban, 1978b; Buggeln, Lobban,  the  1975;  and towards  1977;  Luning  Schmitz  et.al.,  meristematic  and  1972); regions.  r e p r o d u c t i v e r e g i o n s has not been r e p o r t e d f o r members  of the L a m i n a r i a c e a e , but may occur among some more s p e c i a l i z e d members of the Lessoniaceae  (Lobban,  1978b).  - 3 -  K e l p gametophytes are known p r i m a r i l y from l a b o r a t o r y they have o c c a s i o n a l l y been found i n the f i e l d Moe,  unpubl.).  Gametophytes  heteromorphic  (Kain,  1938;  1933;  McKay,  reproductive  at  f i l a m e n t s , each  1979;  are Cole,  Harries,  an  early,  cell  (Moss e t . a l . , 1981;  dioecious 1968;  1932).  and  sexes  H o l l e n b e r g , 1939; Female  although  Klinger  are  (Luning, 1980;  Luning  and  Dring,  Luning and  1972;  Neushul,  1978;  grow to become t u f t e d  Neushul,  the  laboratory,  f i l a m e n t o u s gametophytes may c u l t u r e d to produce  The  Luning  Hsiao and D r u e h l , 1971).  to many c e l l s b e f o r e  In  be  become  can be transformed i n t o an oogonium.  f i l a m e n t o u s t u f t s of few 1978).  Herbst,  may  Oogonium f o r m a t i o n i s dependent, i n the l a b o r a t o r y , upon temperature quality  and  normally  C l a r e and  gametophytes  s i n g l e - c e l l e d stage, or may  of which p o t e n t i a l l y  studies,  fragmented,  light  Dring,  1975;  Male gametophytes grow to  becoming  both  and  and  male  fertile and  (Luning  female  resuspended,  and  and  vegetative subsequently  multiple reproductive individuals.  p e r s i s t e n c e and r e p r o d u c t i v e b e h a v i o r of gametophytes i n the f i e l d i s  l a r g e l y unknown.  In one  e x c e p t i o n a l study, H s i a o and Druehl  (1973) o u t p l a n t e d  l a b e l e d gametophytes of L a m i n a r i a s a c c h a r i n a i n order to f o l l o w t h e i r development.  They r e p o r t e d c o n t i n u a l  the study p e r i o d of J u l y 1968, sporophytes  only  in  the  to  late  oogenesis and  June  1971,  winter  and  but  sporophyte observed  i n the e a r l y  i n i t i a t i o n for development  fall.  The  authors  sporophytes  action  embryosporophytes, r a t h e r than by  environmental  environmental  s u p p r e s s i o n of  K a i n (1964) r e c o g n i z e d gametophytes indefinite  effects  potentially gamete  on  the  limited  of  concluded t h a t e s t a b l i s h m e n t of macroscopic of  is  seasonal  by  the  gametogenesis.  that allows  production".  filamentous gametophytes Luning  and  vegetative to  growth  "become  Neushul  of  perennial  (1978)  argue  female with that  - 4 "optimal"  conditions  of  temperature  among s i n g l e - c e l l e d females, coastal  waters.  precocious  The  existence  of  a  dynamic  oogenesis lacking  in  t r a d e - o f f between  development of a s i n g l e oogonium and delayed p r o d u c t i o n of m u l t i p l e  has  implications  Charnov  and  Schaffer's  iteroparous  strategies;  f o r fecundity (1973)  of  offspring,  for fragmentation functionally  which can be argued a n a l o g o u s l y t o  discussion  briefly,  p r o d u c t i o n of fewer o f f s p r i n g ,  those  regarding  authors  f o r the case  versus  a t t r i b u t e advantage t o e a r l y  of the expanding p o p u l a t i o n .  among f i l a m e n t o u s  gametophytes  e q u i v a l e n t t o i t e r o p a r o u s organisms.  semelparity  semelparous  r a t h e r than t o delayed p r o d u c t i o n of a  gametophyte r e p r o d u c t i v e b e h a v i o r of e i t h e r  l i g h t q u a l i t y promote  but note that such c o n d i t i o n s may be  possible  oogonia  number  and  i s important  renders  such  greater  The c a p a c i t y gametophytes  The apparent p l a s t i c i t y of  i n that f a c u l t a t i v e  expression  or i t e r o p a r i t y has not been p r e v i o u s l y c o n s i d e r e d i n the  literature.  The which  a  instantaneous given  r a t e of p o p u l a t i o n i n c r e a s e  population  is  expanding  or  ( r ) d e s c r i b e s the  declining,  rate  and i s a measure of  f i t n e s s i n t h a t i t r e f l e c t s the s u c c e s s f u l p r o d u c t i o n of o f f s p r i n g by of  a  population.  members  " r " i s a f u n c t i o n of the p r o b a b i l i t i e s of s u r v i v a l and  r e p r o d u c t i o n , as d e f i n e d by the E u l e r  equation:  1(x) m(x) dx = 1 where  l(x)=the  instantaneous  probability birth  rate,  of and  Leslie-type  matrix,  the elements of the  (1)  survival dx=time  Anderson, 1980; Stearns, 1976; Lotka,  Observed v a l u e s  at  of l ( x ) and m(x)  to  age  interval  x  from  birth,  m(x)=the  T  t o T+l ( c f . Michod and  1956).  may  be  presented  as  elements  of  a  i n which p r o b a b i l i t i e s of a g e - s p e c i f i c f e c u n d i t y comprise first  row  vector,  and  age-specefic  probabilities  of  - 5 -  survival  are  listed  elements are z e r o .  on  The  the  sub-diagonal  m a t r i x may  be  solved  ( L e s l i e , 1945). f o r the  A l l other m a t r i x  dominant  i  eigenvalue, X  then:  (2)  r = lnX. The rates,  L e s l i e m a t r i x has and  1945), and the  the  has  been a p p l i e d ,  trees  (Usher, 1966).  matrix  however.  been w i d e l y used i n p r o j e c t i o n of p o p u l a t i o n  for  For  the  f o r example, to p o p u l a t i o n s of humans ( L e s l i e , The  purposes  be  at  the  d e t e r m i n a t i o n of l ( x ) and m(x)  be  age  in  p r o j e c t i o n may  increase,  stable  construction be  the m a t r i x model  distribution,  and  constraining, demands  that  consider  f o r the purposes of p o p u l a t i o n  There e x i s t , however, a number  complexity  within  the  or  dissimilar Common  to  both non-complex and  that a single ploidy  level  history,  alternate  and  that  t r a n s i e n t episodes of meiosis. parameters occurring fecundity  the l i f e  projection  Further, (l(x), within  ploidy  m(x)) the  of stage  (as the  maintained  in  " r " or X) stage  which  syngamy  prevailing  ploidy.  1981a;  Werner,  are  1979).  assumption the  life  r e s t r i c t e d to  closely the  follows  demographic  ploidy.  the  are  demographically-  i s incorporated For  which  (Mills,  throughout  ( u s u a l l y In)  of t r a n s i t i o n a l p l o i d y  stage of p r e v a i l i n g  and  i s determined by of  models  h i s t o r y models i s the  levels  sexual r e p r o d u c t i o n fitness  term of the  complex l i f e is  dynamics  (Hubbell  history,  These t y p i c a l l y  i n which s e v e r a l  history  ( u s u a l l y 2n)  projection  history.  stage-specific  to p o p u l a t i o n s of h i g h e r p l a n t s stages occur w i t h i n  of  diplontic l i f e  t a i l o r e d to insect populations with 1981b),  that  empirical  s u i t e d l a r g e l y to d i p l o n t i c organisms without complexity of l i f e  such as humans.  of  possible.  L e s l i e - t y p e models c o n s t r u c t e d are  assumptions i n h e r e n t  of p o p u l a t i o n  c a l c u l a t i o n of r a t e of  population  growth  Mortality into  diplontic  the life  -  history,  no  fecundity  occurs  in  6 -  the  stage  of  transitional  ploidy,  by  definition.  A simple example may be i l l u s t r a t i v e .  For a sexually reproducing  human,  m(x) d e s c r i b e s the number of daughters born t o a female aged x d u r i n g the time period T to T+l. The v a l u e taken by m(x) i s t h e r e f o r e the product of the f o l l o w i n g q u a n t i t i e s : 1.  number of female gametes  2.  probability  3.  p r o b a b i l i t y of f e r t i l i z a t i o n X (0.5);  4.  p r o b a b i l i t y of zygote s u r v i v a l  The stage of  produced;  of s u r v i v a l of female  to birth.  second and t h i r d terms above r e f e r t o  of  transitional ploidy  of r e d u c i n g the observed  For complex  within  "Mortality" fertilization)  of  because  importantly,  ploidy  because  at  no  as  and  point  during  the  stage  of  multiplied  by  (0.5).  Birth  of  twins  case and w i l l not be c o n s i d e r e d here.  those  p o p u l a t i o n dynamics.  i n t o the  can the a b s o l u t e number of o f f s p r i n g produced exceed the  e l a b o r a t i o n of the h a p l o i d stage i n the such  the  the v e r y s m a l l temporal window i n which they  a b s o l u t e number of m e i o t i c p r o d u c t s constitutes a special  has  fecundity.  term  m(x)  the  i n either  each of the f o r e g o i n g terms i s absorbed  transitional  models  gametes p r i o r t o  occurring  d i p l o n t i c organisms,  occur, and, more  The  events  ( i n t h i s example. I n ) .  these terms (eg. death of female  effect  gametes t o f e r t i l i z a t i o n ;  cited  kelp  life  history  renders  above i n t r a c t a b l e i n p r e c i s e l y d e s c r i b i n g k e l p  The i n t e r p o s i t i o n of an i n d e t e r m i n a t e number of  between  meiosis  syngamy a l l o w s the a b s o l u t e number of d i p l o i d  produced  t o exceed the number of o r i g i n a l m e i o t i c p r o d u c t s X (0.5),  mitoses offspring  if  these  haploid  m i t o t i c products  are u l t i m a t e l y transformed  consequence of t h i s p o s s i b i l i t y  is  the  " s u c c e s s f u l " h a p l o i d genotype p r i o r t o  The  potential  population. mortality matrices  Relevant can  be  on the net r e p r o d u c t i v e  estimated  tenable  that  s e l e c t i v e pressures  proliferation  i n c r e a s e d by  by  For d i p l o h a p l o n t s  changes  in  fitness  such may  as  the  result  upon f e c u n d i t y and m o r t a l i t y i n be  the  action  either  kelps  the and  stage;  stage.  Under v a r y i n g s e l e c t i v e regimes, the h a p l o i d gametophyte differentially  to  overall  it  is  from the a c t i o n of  e f f e c t e d w i t h i n e i t h e r the gametophyte or  contribute  a  c o n s t r u c t i o n of the a p p r o p r i a t e L e s l i e - t y p e  i n f i t n e s s may  may  of  r a t e s of i n d i v i d u a l s w i t h i n  change  sporophyte  important  changes i n the parameters of a g e - s p e c i f i c f e c u n d i t y  from e m p i r i c a l data.  therefore  for  An  recombination.  average f i t n e s s of a p o p u l a t i o n tends to be  of s e l e c t i v e p r e s s u r e s  to oogonia.  that  is,  sporophyte  and  diploid  (zygote-to-zygote)  fitness.  If  the p o t e n t i a l f o r p o p u l a t i o n  independently stage,  of  and  for  both stages  L e s l i e f o r m u l a t i o n are met. then  be  some product  exists  within  the  In  stage  i n a d d i t i o n to the p o t e n t i a l f o r i n c r e a s e w i t h i n the  then the c o n s t r u c t i o n of l i f e  possible  increase  tables  independently, The  should  be  i f the q u a l i f y i n g assumptions of  the  observable  and  Leslie  matrices  2n  r a t e of p o p u l a t i o n i n c r e a s e  of the p r o b a b i i t i e s of the two  should  independently-constructed  matrices.  I n t e r s p e c i f i c v a r i a t i o n i n the l i f e well  documented  (Laminaria J.  Ag.)  perennial  (Luning,  1980;  Kain,  h i s t o r y of 1979).  the  kelp  Sporophytes may  ephemera S e t c h e l l ) , annual (Cymathere t r i p l i c a t a  s h o r t - l i v e d perennial (Laminaria  (Laminaria  setchellii Silva).  sporophyte  (Post,  be  is  ephemeral et  Rupr.)  g r o e n l a n d i c a Rosenv.), or l o n g - l i v e d It  is  reasonable  to  expect  that  - 8 -  gametophytes  of  different  parameters.  Selective  taxa  also  pressures  exhibit  should  act  variation to  in  maximize  life  history  the  average  p r o b a b i l i t y of s u c c e s s f u l r e p r o d u c t i o n by members of a p o p u l a t i o n , and f o r the kelps,  such  maximization  populations  It  of  occur  within  multiplicatively  the i n d e p e n d e n t l y - c o n s t r u c t e d  r e d u c t i o n of the "complex"  seedbank: by w i s e l y sporophyte  matrix  age-classified differential  chosing  their  life  seedbank  especially  matrix.  Schmidt and Lawlor (1983) have  h i s t o r y of an annual p l a n t w i t h a  sampling  time,  they  The  results  are  have  then  of X t o changes i n l i f e - h i s t o r y  in  the case  gametophyte  empirical  Fischer express  population.  determination  of  than  used  to  test  parameters.  t o the k e l p  The both  formulation, sporophyte  however, and  life  would  gametophyte  unidentifiable  of r e p r o d u c t i v e v a l u e  of f u t u r e p r o d u c t i o n of o f f s p r i n g d i s c o u n t e d  For an expanding p o p u l a t i o n , valuable  the  f o r the  i n the f i e l d .  (1931) i n t r o d u c e d the concept  the v a l u e  reduced  of an annual sporophyte a l t e r n a t i n g w i t h an  s u r v i v o r s h i p and f e c u n d i t y , and these q u a n t i t i e s a r e gametophyte stage  by  t o a column v e c t o r , and have m u l t i p l i e d t h i s v e c t o r by the  sensitivity  age-structured require  gametophyte  L e s l i e - t y p e matrices  Such a m a n i p u l a t i o n may have some l i m i t e d a p p l i c a b i l i t y history,  and  t o reduce the c o m p l e x i t i e s of k e l p p o p u l a t i o n dynamics  the sporophyte and gametophyte p o p u l a t i o n s .  justified  sporophyte  independently.  i s tempting  combining  should  the  same  N  number  d e c l i n i n g p o p u l a t i o n the converse  offspring of  produced  offspring  may be t r u e .  at  time  in  order  to  t o the p r e s e n t . T+0  are more  produced a t time T + l .  For a  - 9 -  Schaffer for  (1974) and T a y l o r e t . a l .  strictly  (1974) have independently  at each age,  subject  to  change i n r e p r o d u c t i v e e f f o r t w i t h time has no e f f e c t p r e v i o u s r e p r o d u c t i v e episodes. stage-classified  populations  Caswell with  Caswell  (1982) has  complex l i f e  maximizing f i t n e s s i s e q u i v a l e n t to  as a s p e c i a l  maximizing  the  constraints  further  shown  that,  reproductive  value  at  vegetative  are f o r c e d to accommodate age  as  (gametophyte).  well  which  as  sexual  s t r u c t u r e , stage  reproduction  Of the three models, C a s w e l l ' s may  order t o accomodate these graph  is  each et.al.  of h i s more g e n e r a l i z e d model.  l i f e history,  and  for  h i s t o r i e s of a c e r t a i n form,  t r e a t s the a g e - c l a s s i f i e d models of S c h a f f e r and T a y l o r  case  that  on o f f s p r i n g produced i n  The models of S c h a f f e r , T a y l o r e t . a l . , and C a s w e l l , when a p p l i e d kelp  that,  a g e - s t r u c t u r e d p o p u l a t i o n s , maximizing f i t n e s s i s e q u i v a l e n t to  maximizing r e p r o d u c t i v e v a l u e  stage;  argued  added parameters, by  descriptive  of  the  in  at  to  the  complexity,  least  one  stage  be m o d i f i e d most e a s i l y  construction  diplohaplontic  of  a  in  life-cycle  l i f e history  and which  remains c o n s i s t e n t w i t h the s t a t e d assumptions of the model.  Models dependent upon s t a g e - c l a s s i f i c a t i o n are a p p l i e d t o the k e l p s difficulty.  Stage  c l a s s i f i c a t i o n s have been developed  d e s c r i b e more p r e c i s e l y p o p u l a t i o n s i n which little  bearing  on  schedules  on  c l a s s i f i c a t i o n i s t h e r e f o r e meant t o kelps,  the  stage  and  perhaps two,  fecundity replace  c l a s s i f i c a t i o n which may  sporophyte/gametophyte a l t e r n a t i o n may age  structures.  strict  be  age  age and  expressly i n order classification survivorship.  classification.  invoked  complexity  Stage  For  have superimposed upon i t at l e a s t  That i s , any  age  s t r u c t u r e expressed  i n h e r e n t i n the k e l p l i f e h i s t o r y  to has  i n order t o d e s c r i b e  sporophyte or gametophyte p o p u l a t i o n s e x i s t s i n a d d i t i o n to stage The  with  by  the the one, the  complexity.  i s t h e r e f o r e not analogous t o  - 10  the  "complexities"  other  of h i g h e r  plant  and  history  limitation Williams,  theory  (Snell 1966). to  available  resources  reproduction.  and  risk  predicated  King,  individuals,  1977;  and  between  Resource  reproduction-associated increased  is  populations  and  considered  inverse  inverse  with  by-  must  thus  and  We  s o l e l y a f u n c t i o n of to  therefore  processes implies  cost  the  1966;  resources  are  partition  the  of  the  prediction  (Bell, and  1980).  growth  comparisons,  itself (Bell,  sufficient  meiospore  f u n c t i o n a l l y equivalent  The  and  kelp  t o a d i p l o n t i c organism. and  The  though to  a the  resources  adult  existence  survival of  testable  such by  documentation  prove  the  an  both of  the  existence  of  some parameters of  time being,  production,  fecundity.  t h a t sporophyte f e c u n d i t y  of  1984).  can assume, f o r the  overall  and  existence  that  survivorship i s  cost h y p o t h e s i s can be used t o e v a l u a t e  contribute  of  Cody,  processes.  fecundity  intraspecific  r e l a t i o n s h i p i s not  history.  1970;  resource  T h i s cost f u n c t i o n i s u s u a l l y e s t i m a t e d as  r e l a t i o n s h i p between f e c u n d i t y  reproduction-associated  The  amount  of  of i n d i v i d u a l m o r t a l i t y r e s u l t i n g from d i v e r s i o n of  inversely  interspecific  Bossert,  limiting  partitioning  cost h y p o t h e s i s i n t u r n a l l o w s  vary  assumption  and  alternative  from growth p r o c e s s e s to r e p r o d u c t i v e  The  the  individuals  the  cost.  on  Gadgil  That i s , a f i n i t e  available  life  insect  authors.  Life  will  -  that fecundity that  can  is  intraspecific  do  not  thus rendered  then go on to p r e d i c t  s u r v i v o r s h i p are i n v e r s e l y r e l a t e d , and  t h i s p r e d i c t i o n at both i n t e r s p e c i f i c and  kelp  i n kelps i s  gametophytes  sporophyte We  the  levels.  can t e s t  - 11 -  The  e v o l u t i o n of  delayed  maturity  has  sometimes  been  s e l e c t i o n f o r i n c r e a s e d f e c u n d i t y which may accompany a delay time-to-maturity 1970;  Tinkle,  1969).  The thus  of  the  can be  hypotheses of r e p r o d u c t i o n - a s s o c i a t e d  of  two  Bossert,  A p o s t u l a t e d i n c r e a s e i n f e c u n d i t y w i t h an a s s o c i a t e d  i f f e c u n d i t y and developmental t i m e - t o - m a t u r i t y  allow  to  i n developmental  (Ste arns and C r a n d a l l , 1981; B e l l , 1980; G a d g i l and  decrease i n developmental time i s t e s t a b l e i n the context history,  attributed  testable  predictions  to  cost and  be  made  kelp  life  estimated.  delayed  maturity  f o r populations  of k e l p  sporophytes: 1) t h a t the annual semelparous sporophyte w i l l  exhibit  a  greater  shorter  f o r the  fecundity  than the p e r e n n i a l i t e r o p a r o u s sporophyte; and 2) t h a t developmental t i m e - t o - m a t u r i t y sporophyte,  provided  i t exhibits  w i l l be  a  semelparous  g r e a t e r f e c u n d i t y than the i t e r o p a r o u s  sporophyte.  S e v e r a l authors increase  with  have argued t h a t  age  among  iteroparous  S c h a f f e r , 1974; G a d g i l and B o s s e r t , to  vegetative  effort  (Pianka  reproductive  and Parker, effort  that  increase with  by  the r a t i o  For  This  (Pianka  The r a t i o of  the sorus  kelps,  then,  production  formulation  generally  and Parker, 1975;  reproductive  tissue  permits  one  can  relative a  estimate to  third  total  testable  production w i l l  sporophytes.  s p e c i e s were chosen f o r the ephemera  should  of sorus p r o d u c t i o n t o t o t a l blade  age among i t e r o p a r o u s  Laminaria  effort  can be used as a measure of r e p r o d u c t i v e  measuring  production.  Two congeneric study.  1975).  organisms  1970).  t i s s u e per i n d i v i d u a l  ( v e g e t a t i v e ) blade prediction  reproductive  Setchell  purposes  of  a  i s a short-lived,semelparous  comparative sporophyte  - 12 -  found i n lower i n t e r t i d a l setchellii  Silva  and s u b t i d a l h a b i t a t s of the  i s a l o n g - l i v e d i t e r o p a r o u s sporophyte  h a b i t a t and d i s t r i b u t i o n . another  at  many  sites  different  not  mucilage  by the presence  ducts  Sporophyte  intermix,  each  being  restricted  described  from  collections  to  substrata.  County, C a l i f o r n i a p r i o r  i t s congeners  L.  a d j a c e n t t o one  i n B a r k l e y Sound, Vancouver I s l a n d , B.C.  L a m i n a r i a ephemera was o r i g i n a l l y Monterey  Pacific.  of roughly the same  These s p e c i e s may be found growing  p o p u l a t i o n s of the two s p e c i e s do slightly  eastern  t o 1901.  distributed  California  (Abbott  from  of a d i s c o i d h o l d f a s t ,  and  Volga  Hollenberg,  in  The s p e c i e s i s d i s t i n g u i s h e d from  from both the s t i p e and blade  reportedly  made  Island, 1976),  and  by  the  (Druehl, 1968). Alaska  to  absence  of  The s p e c i e s i s  Monterey  County,  but extends a t l e a s t t o San L u i s  Obispo County i n the south ( p e r s . o b s . ) .  L a m i n a r i a ephemera sporophytes d i s p l a y discoid  holdfast  the blade  single  formation  rather  (but sometimes d i s s e c t e d ) .  (Abbott  Sori  sorus formed Sorus  morphology.  The  i s s m a l l and w i t h o u t h a p t e r a , the s t i p e f l e x i b l e and t e r e t e ,  and  The sorus i s r e p o r t e d l y l i n e a r i n  H o l l e n b e r g , 1976; Druehl, 1968),  may i n f a c t be as broad as the w i d t h of the blade obs.).  simple  are  formed  though  soral  ( S e t c h e l l , 1901;  asynchronously on e i t h e r  patches  and  pers.  side of the b l a d e , and the  on one side i s u s u a l l y much l a r g e r than t h a t formed on the o t h e r .  formation  is  i n i t i a t e d p r o x i m a l l y t o the t r a n s i t i o n zone and proceeds  distally.  L a m i n a r i a ephemera sporophytes a r e a h i g h l y k e l p f l o r a of B a r k l e y Sound, B.C. i n March, depending sporophytes  Juvenile  upon the s i t e and  disappear  by  late  June  component  sporophytes are f i r s t  prevailing or  seasonal  early  weather July.  of the  identifiable  conditions. Sporophytes  Most may be  - 13  intertidal, substrata coarse  but  are  of  more  cobble  sand.  I n d i v i d u a l s are only  Laminaria  typical  setchellii  Pacific,  Me x i c o  found  and  i s hapterous and  throughout.  along  setchellii  exposed,  monospecific  o l d ) are found  1976).  i n both  the  of  granitic  species  of  the  t o Ensenada,  The  species  s t i p e and b l a d e .  among stands  (1968;  d e n t i g e r a ( N i c h o l s o n , 1976) and  the  commonly i n h a b i t s  and may  Druehl  rocky  shores.  former  1979) i s not  specific  a c c o r d i n g t o Druehl  stable  and  Mature  is  The  form dense canopies.  Juveniles  epithet  of a d u l t s of the s p e c i e s , but may  is  substrata i n nearly  to  2  years  a l s o occur  substrata  be  (1979).  exist (1  will  considered  permanent  plants  the p e r i p h e r i e s of p o p u l a t i o n s and on n e w l y - a v a i l a b l e adult  to  e r e c t s t i p e and l a r g e , r e p e a t e d l y d i s s e c t e d  setchellii,  wave-swept  stands,  subtidal  (Druehl, 1968)  Hollenberg,  r e s e r v e d f o r a s p e c i e s of A l a s k a n L a m i n a r i a ,  Laminaria  the  perennial  Alaska  (1957) and  Laminaria  c o n s p e c i f i c w i t h L.  confined  ramifying.  nomenclature of S i l v a  followed  often  s o f t bottoms of pebble or  on  S i l v a i s a woody-stiped  (Abbott  are  Sound.  and by the presence of mucilage ducts  The  to be  rarely  of B a r k l e y  c h a r a c t e r i z e d by a w e l l - d e v e l o p e d ,  holdfast  and  u n d e r l a i n by  d i s t r i b u t e d from Yakutat,  Baja C a l i f o r n i a ,  blade,  subtidal,  or small b o u l d e r s  pavements and o u t c r o p s  eastern  commonly  -  along  remote  from  populations.  V i s i b l e r i n g s formed by obvious  in  basal  cross-section  other woody-stiped s p e c i e s , (Eain,  1963),  radiata  (C. Ag.)  seasonal  Pterygophora J . Ag.  of  including  development of a the s t i p e . Laminaria  californica  (Novaczek, 1981).  Ruprecht  secondary  cortex  are  S i m i l a r r i n g s are common to hyperborea  (Gunn.)  Foslie  (Frye, 1918), and E c k l o n i a  - 14  The blade of L a m i n a r i a initiated  from  setchellii  -  is  deciduous.  site.  be  meristematic seasonal latter  shed e n t i r e l y , region.  initiation case,  of of  this trait  the e x i s t i n g blade may  r e t e n t i o n or l o s s of the e x i s t i n g blade and of s i t e .  There  generally  and  lose  the  A l l first  after  blade.  exisitng  A s m a l l percentage  blade  (1969; 1971)  entirely,  and  and second y e a r p l a n t s stipes.  of  older  persist  of the blade of L a m i n a r i a hyperborea.  Most  third  blade  plants  do,  temporarily  as  has r e p o r t e d a s i m i l a r ontogney f o r the  t h a t the e x i s t i n g blade of L. hyperborea occurence  independent  some p o r t i o n of the e x i s t i n g  seasonal  The  sloughed s h o r t l y  Older p l a n t s (5 and more  Luning  initiation.  this  seems t o be  bladeless stipes. renewal  In  'overwinter' as bare  r e t a i n at l e a s t  beyond i n i t i a t i o n of the new however,  zone.  until  i s , however, some age-dependent e x p r e s s i o n  among the p o p u l a t i o n s s t u d i e d .  age)  active  blade.  and f o u r t h y e a r p l a n t s a l s o shed the e x i s t i n g b l a d e . of  upon  be r e t a i n e d  blade t i s s u e s form the t r a n s i t i o n  shed the e x i s t i n g blade e n t i r e l y ,  years  is  twelve months, at which  remnants of the o l d e r blade are e n t i r e l y  population  and  leaving a bladeless stipe with a l a t e n t l y  Alternatively,  of new  i n i t i a t i o n of the new  Seasonal  blade  upon the p o p u l a t i o n  The blade develops and p e r s i s t s f o r about  time i t may  single  the m e r i s t e m a t i c r e g i o n at the t r a n s i t i o n zone, normally i n the  months of September through December, depending the  A  I t appears,  however,  i s always m a i n t a i n e d beyond new  blade  o f - b l a d e l e s s s t i p e s has not been r e p o r t e d f o r L.  hyperborea.  Small s o r a l patches are g e n e r a l l y i n i t i a t e d fronds  of  Laminaria  s y m m e t r i c a l l y on e i t h e r the  sorus  extends  in  setchellii,  and  side of the b l a d e . a  proximal  distally  usually As sorus  direction  and  form  on  well-developed  synchronously  development ultimately  and  progresses, adjoins  the  - 15  t r a n s i t i o n zone. (1971) has  In to  Not  -  a l l p l a n t s , however, produce such e x t e n s i v e s o r i .  d e s c r i b e d s i m i l a r development of s o r i  the f a l l  f o r Laminaria  blade  tissues,  functional  s o r i may  along proximal r e g i o n s of the o l d blade and d i s t a l The  observation  Laminaria  of  simultaneous  setchellii  independent  hyperborea.  months, when remnants of the o l d blade p e r s i s t  newly-formed  of  indicates  the  age  sorus  that  sorus  of the blade  on new  distal  concomitantly  r e g i o n s of the  initiation  tissues.  and are  be produced  formation  Eain  new  blade.  and o l d b l a d e s of  and  development  In the f i e l d ,  sori  are  have been  observed on f r o n d s e s t i m a t e d t o be l e s s than one month o l d .  Blade  surface  interpsecific Blade  is  deemed  the  most  with  meristodermal  Vegetative  of  parameter  for  blade,  and  mitotic  the  entire  c e l l s containing  transformations  of  and r e p r o d u c t i v e ( s o r a l ) areas a l o n g the blade  e a s i l y d i s t i n g u i s h e d and e v a l u a t e d w i t h  be  the  and u p p e r - c o r t i c a l  Sorus f o r m a t i o n i s the product  meristoderm.  can be  appropriate  comparisons of meiospore p r o d u c t i o n w i t h i n the genus L a m i n a r i a .  pigmented,  chloroplasts.  can  is  anatomy i s c o n s i s t e n t along the l e n g t h of  blade  the  area  little  ambiguity.  Fecundity  e s t i m a t e d by q u a n t i f i c a t i o n of the number of spores produced  per u n i t  sorus area.  Comparison of dry weight of the blade for  the  purposes  of  demonstrated f o r two along  the  present  tissues i s considered inappropriate  study.  Euppers  and Eremer (1978) have  s p e c i e s of L a m i n a r i a t h a t dry weight per u n i t area v a r i e s  the l e n g t h of the b l a d e ; dry weight per u n i t area may  as w e l l . reflect  Spatial energetic  and u t i l i z a t i o n parameter  in  and  seasonal  processes  i n c o n s i s t e n c i e s i n dry  present  weight  per  unit  and c o n s t r a i n t s , e s p e c i a l l y i n terms of  of carbohydrates. the  change s e a s o n a l l y  study  However, use potentially  of dry weight as a confounds  the  area  storage  comparative  processes  of  - 16 -  carbohydrate  metabolism  observations epiphytes of  t h i s  to  of  dry  t o t a l  study.  w i t h  weight  weight.  those  of  n e c e s s a r i l y Dry  weight  meiospore include i s  the  therefore  production. extraneous not  used  A d d i t i o n a l l y , c o n t r i b u t i o n  for  the  of  purposes  - 17 -  CHAPTER 2 SEASONAL PATTERNS OF RECRUITMENT IN LAMINARIA EPHEMERA  INTRODUCTION  The ephemera  cobble at  and  Cable  seasonal b u r i a l . unstable  Beach  is  ephemera sporophytes or  supporting  and  The seasonal  substrata  gametophyte  boulders  of  dense  overgrown  recurrence  interest.  Laminaria  and s u b j e c t t o  of s h o r t - l i v e d sporophytes Disallowing  that  on  recruitment  such of L.  occurs beyond the s e t t l i n g of meiospores, the L. ephemera  embryosporophyte must p e r s i s t f o r at l e a s t  by  of  a t E x e c u t i o n Bay were u n s t a b l e  i n the f o l l o w i n g season r e q u i r e s t h a t gametophytes not  populations  other  algae,  or  7 months.  embryosporophytes  grazed by h e r b i v o r e s , or scoured  gametophytes are g e n e r a l l y capable  of s u r v i v a l  Success  i n the dark  away.  (Kain,  Kelp  1964;  pers.  obs.).  burial  f o r extended p e r i o d s of 7 months or more, i f the o v e r l y i n g sediment  of  grain  a  size or  sufficient  to  stands  been r e p e a t e d l y  Few  or  simultaneously californica,  conceivably  no  other with  Alaria  leads  to  the sediment.  emerge  to  produce  of the substratum.  Laminaria  the  production  of  Such h i g h d e n s i t i e s of L.  species  marginata,  subsequently  uncovering  i n the f i e l d  kelp  within  is  o b v i a t e s problems of overgrowth, g r a z i n g , and  of L. ephemera.  observed  oxygenation  could  upon seasonal  Such a s c e n a r i o p o t e n t i a l l y and  permit  embryosporophytes  macroscopic sporophytes  monospecific  and  I t might be p o s s i b l e , t h e r e f o r e , t h a t gametophytes can s u r v i v e  Gametophytes  scouring,  are  nearly  ephemera  have  (pers. obs.).  i n Barkley  ephemera. and  dense,  Sound  Species  Cymathere  are  such  triplicata  as  reproductive Pterygophora tend  to  be  - 18 -  reproductive  later  i n the season than L. ephemera.  i n r e p r o d u c t i o n , when coupled w i t h seasonal b u r i a l reduces  the  probability  of  k e l p gametophytes, i f b u r i a l  overgrowth  T h i s temporal  difference  and emergence of s u b s t r a t a ,  or e x c l u s i o n of L. ephemera by  occurs p r i o r t o spore p r o d u c t i o n by  other  kelps  other  than L. ephemera.  In an attempt  t o document the  ephemera sporophyte  pattern  of  Three  questions  1) i n which months were c o b b l e s s u p p o r t i n g L. ephemera  to  cobble  when  did  Laminaria  in s i t u and monitored f o r  through November 1982).  b u r i e d and subsequently uncovered? 2) relative  seasonal  r e c r u i t m e n t , cobbles were tagged  an 18 month p e r i o d (June 1981 addressed:  observed  meiospore  were  sporophytes  production  b u r i a l ? and 3) would L. ephemera sporophytes  occur  reappear i n  the f o l l o w i n g season on cobbles which had been p r e v i o u s l y b u r i e d ?  MATERIALS AND  Thirty-nine 2.1)  on  27  cobbles were tagged and numbered i n E x e c u t i o n Bay  June 1981.  Cobbles  were of minimum dimensions  ephemera sporophytes on  some  marginata, of  cobbles,  additional  15 cm  epoxy  putty  to  the  m  , and  juvenile  and Cymathere t r i p l i c a t a .  underwater  4-5 3  at  a t the time of t a g g i n g . including  (re: Figure  i n c l u d e d i n the study were w i t h i n an area of  2 l e s s than 50 m , on a sandy bottom,  tagging  METHODS  depth.  Cobbles  for  supported a t l e a s t 5 L a m i n a r i a  Other  algal  Pterygophora  s p e c i e s were p r e s e n t californica,  Tags were f i x e d in s i t u upper  chosen  of  each  application cobble.  Five  epoxy tags were f i x e d on r o c k w a l l s b o r d e r i n g the study s i t e ;  these  were to serve as i n d i c a t o r s of tag l o s s .  surface  by  Alaria  - 19 -  F o r t y - e i g h t hours were a l l o w e d f o r c u r i n g of the a p p l i e d epoxy. s i x of the o r i g i n a l was  39 tags were w e l l - c u r e d a f t e r 48 hours,  Thirty-  and the  experiment  begun w i t h these 36 c o b b l e s .  On 29 June 1981,  and  at  approximately  r e c o v e r y of the tagged cobbles was site. of  D u r i n g these other  algal  attempted  surveys, the presence species  on  the  monthly  intervals  thereafter,  by underwater survey of the  study  or absence of L a m i n a r i a ephemera and  tagged  cobbles  r e p r o d u c t i v e c o n d i t i o n of L a m i n a r i a ephemera was  was  recorded,  and  the  of  the  have i n d i c a t e d  that  noted.  RESULTS  L a m i n a r i a ephemera sporophytes were r e p r o d u c t i v e upon i n i t i a t i o n study  (29  June  1981).  Observations  at  E x e c u t i o n Bay  meiospore p r o d u c t i o n may  b e g i n as e a r l y as A p r i l  (re:  Laminaria  Chapter  3).  No  cobbles, or w i t h i n the sporophytes subsequent  did  surveys.  californica of sand.  not  study  ephemera  area,  reappear  on  on these  On 05 August 1981,  remaining  05  and may  continue  sporophytes August cobbles  remained  1981, at  t h e r e was  and  any  evidence  time  of such tumbling p e r s i s t e d  September, 29 October,  through  and 26 November  Surveys made a f t e r 26 November 1981 This  failure  is  sand and p e b b l e .  attributed  to b u r i a l  tagged  ephemera d u r i n g the  Pterygophora  of tumbling of tagged  the  July  approximately  judged by p o s i t i o n of the tags and by o r i e n t a t i o n of s t i p e s of P. Evidence  on  L.  the h o l d f a s t s of j u v e n i l e  on some cobbles were b u r i e d beneath  On 28 August 1981,  until  subsequent  1 cm  cobbles,  californica.  surveys  of  25  1981.  f a i l e d t o r e c o v e r any  tagged  cobbles.  of the study s i t e beneath 20-30 cm of  Surveys were c o n t i n u e d through November 1982;  tagged  cobbles  - 20 -  were  not  uncovered  during  this entire period.  cobbles i s assumed t o r e f l e c t  burial  The disappearance  of tagged  r a t h e r than t a g l o s s ; epoxy tags  t o r o c k w a l l s b o r d e r i n g the study s i t e were o b s e r v a b l e throughout  applied  the 18 month  study p e r i o d .  B u r i a l was expressed  as  estimated the  as  percentage  the  rate  of  cobble  disappearance,  and  is  of tagged cobbles not r e c o v e r e d d u r i n g surveys.  V a l u e s are g i v e n i n T a b l e 2.1.  Estimated b u r i a l  November  l e s s ; b u r i a l was e s t i m a t e d t o be 69.4% f o r the  1981  was  11.1%  or  f o r every  survey p r i o r t o  survey of 26 November 1981. No tags were r e c o v e r e d d u r i n g the survey December 1981, or at any time  made  26  11  thereafter.  DISCUSSION  The b u r i a l of cobbles w i t h i n the study s i t e Most fall  cobbles exposed i n the e a r l y  sand and pebble  Summer pebble,  hydrographic again  immediately be  of  exposing  duration  in  remove  cobbles,  following b u r i a l . excess  seasonal  That  but  the  phenomenon.  exposed u n t i l  occurs.  t r a n s p o r t by water motion conditions  a  summer (June) remain  (November-December), at which time b u r i a l  from  is  Burial  the l a t e  seems t o r e s u l t  associated with winter previously-deposited  removal  may  storms.  sand  and  not occur i n the season  i s , the c y c l e of b u r i a l  and emergence  may  of one y e a r , as i n d i c a t e d by the r e s u l t s of t h i s  study.  Meiospore by  as  much  p r o d u c t i o n by L a m i n a r i a ephemera occurs p r i o r as  4  cobbles are b u r i e d deposition  may  months, assuming t h a t meiospores in  begin  November. as  early  However, as  are produced  tumbling  August,  to cobble  closely  of  cobbles following  burial,  i n J u l y and and  sand  meiospore  - 21  p r o d u c t i o n by L a m i n a r i a ephemera. and Cymathere t r i p l i c a t a  Pterygophora  g e n e r a l l y reproduce  L a m i n a r i a ephemera sporophytes (re:  Chapter  -  3) and bear  i n B a r k l e y Sound grow  minimal  release.  the  and North, 1967).  parent  sporophyte.  the  cobbles  subsequently uncovered  Data  tagged  reported  to  presented  germinate  on  cobbles  here and r e p e a t e d p e r s o n a l cobbles  are  subject  to  for  12  during  I t i s p o s s i b l e that  months  or  more  o b s e r v a t i o n , at an adjacent s i t e , emergence  sporophyte  of  this  study  were  buried  cobbles  initiation.  None  q u a n t i t a t i v e data are not  remained  proportion  viable.  of  from  sori  not  gametophytes  T h i s i s suggested by  of L a m i n a r i a ephemera sporophyte  which of  some  had  these  been b u r i e d f o r 8-12 cobbles  were  tagged,  the  development  months p r i o r however,  to and  available.  In c u l t u r e , L a m i n a r i a ephemera gametophytes are l o n g - l i v e d . germinated  but  a l l o w s only s p e c u l a t i o n r e g a r d i n g the f a t e of L a m i n a r i a  ephemera gametophytes.  upon  blades  burial.  That  buried  on  I t i s t h e r e f o r e r e a s o n a b l e t o assume t h a t  o b s e r v a t i o n s i n d i c a t e t h a t these gametophyte-bearing seasonal  densities  Sorus-bearing  the sporangium i s  most l i b e r a t e d spores of L a m i n a r i a ephemera s e t t l e and nearby  high  and no apparent means of l o n g - d i s t a n c e d i s p e r s a l .  of k e l p spores a f t e r l i b e r a t i o n from  (Anderson  at  s o r i on s i n g l e b l a d e s which are u s u a l l y r e t a i n e d  no means of f l o t a t i o n ,  Dispersal  marginata.  i n August or l a t e r .  the parent p l a n t through the p e r i o d of spore have  californica, Alaria  Gametophtyes  c o l l e c t e d i n B a r k l e y Sound have been r e t a i n e d i n c u l t u r e 2  at low l i g h t  (<50  for three y e a r s  uE/cm / s e c ) ,  or i n the dark w i t h i n t e r m i t t e n t l i g h t  ( K l i n g e r , unpubl.  obs.).  gametophyte l o n g e v i t y  i n the f i e l d ,  m o r t a l i t y .in s i t u may  be  There  though  substantially  the  enhanced.  breaks,  i s no r e a s o n t o assume reduced probability  of  gametophyte  - 22  Other possess value  algal  means in  s p e c i e s growing of  non-sexual  sand-inundated  sporophyte  initiation  sinclairii. sporophytes  of  vegetative  (1967)  sexual  t o new  has  Harkham  reported  sporophytes  species. of  in  from the l i f e  branches plant  of G.  In  thereby  not  i n Laminaria among  eliminating  Newroth linearis  been  develop  reported for this  capacity for  long-distance due  sandy-habitat  risk  be a b c i s e d from  such branches may  from that  parent  aid dispersal,  sand and t h e r e f o r e conducive  reduces  propagation,  non-sexual  or  the  t o sand scour and b u r i a l .  elimates  to  linearis  in  that  reproduction,  or  r i s k of gamete or zygote  L a m i n a r i a ephemera d i f f e r s from o t h e r  s p e c i e s such as L a m i n a r i a s i n c l a i r i i ,  Gymnogongrus  the  the  germination.  vegetative  dispersal  stage  a d d i t i o n , Harkham and Newroth (1972) have noted  t o carpospore r e l e a s e , and t h a t  the  and Markham may  tetrasporophyte  l i n e a r i s which bear c y s t o c a r p s may  carpospore s e t t l e m e n t and  and  demonstrated  development'  history.  have  o s t e n s i b l y t o s u b s t r a t a t e m p o r a r i l y f r e e from  mortality  of a d a p t i v e  incumbent upon germlings i n sandy h a b i t a t s , but does reduce  history.  prior  The  may  which u n i s p o r e s l i b e r a t e d by  Gymnogongrus  tetrasporophytes  has  haptera  'direct  r i s k i n h e r e n t i n r e p r o d u c t i o n by e l i m i n a t i n g the life  Columbia  P a r t h e n o g e n e s i s among l i b e r a t e d carpospores does not a v o i d the  mortality  the  of  directly,  (1972) have proposed t h a t carpospores of and  British  (1968)  propagation  irregulare,  gametophyte  parthenogentically,  in  r e p r o d u c t i o n , which are presumably  Phaeostrophion  sporophytes g i v e r i s e microscopic  i n sandy h a b i t a t s  environments.  by  Hathieson  -  the  Phaeostrophion  species  maintains  an  irregulare, obligatory  m i c r o s c o p i c sexual stage, has no a l t e r n a t i v e means of non-sexual r e p r o d u c t i o n , and has no apparent means of l o n g - d i s t a n c e d i s p e r s a l .  - 23 -  Availability settlement. Chapter  Laminaria  ephemera  is  critical  produces  This  success.  confers  the  greatest  Columbia  the i n t e r t i d a l  summer ( r e :  and when cobbles  of  that  meiospore  meiospore  Laminaria  are  settlement  sinclairii  in  produces s o r i d u r i n g the w i n t e r months, when sand l e v e l s i n  are lowest.  i s c l e a r that  Laminaria  are lowest,  probability  S i m i l a r l y , Markham (1968) has noted  British  for successful  s o r i d u r i n g the e a r l y  3 ) , when sand l e v e l s i n the s u b t i d a l  exposed.  It  of hard substratum  the  microscopic  ephemera must p e r s i s t  sand scour and b u r i a l .  It  is  gametophyte  or  embryosporophyte  of  f o r at l e a s t  7 months i n a h a b i t a t s u b j e c t t o  conceivable  that  burial  actually  enhances  gametophyte s u r v i v o r s h i p i n sandy h a b i t a t s , by r e d u c i n g scour, and by r e d u c i n g or e l i m i n a t i n g g r a z i n g by h e r b i v o r e s seasonal  timing  of  i n the a v a i l a b i l i t y  the  potential  Laminaria  overgrowth  by  other  algae.  meiospore r e l e a s e and s e t t l e m e n t are t h e r e f o r e  both  for  and  t o the meiospores of s u i t a b l e h a r d  successful  germination  prior to b u r i a l .  ephemera i n sandy h a b i t a t s may consequently  truncated  sporophyte  persistent  gametophyte g e n e r a t i o n .  substratum  The  critical, and i n  The success of  be a t t r i b u t a b l e  to i t s  g e n e r a t i o n , p r e c i s e p e r i o d of meiospore l i b e r a t i o n , and  -  F i g u r e 2.1. Map o f B a r k l e y 3 s t u d y s i t e s : W i z a r d Rock,  24  -  Sound, V a n c o u v e r C a b l e B e a c h , and  I s l a n d , showing E x e c u t i o n Bay.  -  25  -  TABLE 2.1.  DATE 29 June 1981  PERCENT 2.77%  05 August 1981  11.11%  28 August 1981  . . 0%  28 September 1981  11.11%  29 October 1981 26 November 1981  5.55% 69.44%  T a b l e 2.1. Number o f tagged c o b b l e s n o t r e c o v e r e d i n each o f s i x s u r v e y s , e x p r e s s e d as a p e r c e n t a g e o f t h e number o f c o b b l e s i n i t i a l l y tagged (n=36).  - 26 -  CHAPTER 3 ALLOCATION TO MEIOSPORE PRODUCTION  IN LAMINARIA EPHEMERA  INTRODUCTION  Sporophytes of general  Laminaria  ephemera  annual  and  semelparous.  phenology of the s p e c i e s i n B a r k l e y Sound i s g i v e n i n Chapter  the semelparous s p e c i e s , we can p r e d i c t short  are  time-to-maturity,  addition,  according  a  to  relatively  high  arguments p r e s e n t e d  The  1.  For  fecundity  and  i n Chapter  1.  a In  a comparison of r e p r o d u c t i v e e f f o r t between p o p u l a t i o n s of L a m i n a r i a  ephemera can be made.  Fecundity number  of  spores  proportional the  among sporophytes  sorus  produced  can be  per  estimated  individual,  by  where  determination  the  the number of spores i s  to the s u r f a c e area of the sorus produced. can be measured g r a p h i c a l l y .  of  Reproductive  The s u r f a c e effort  as the r a t i o of v e g e t a t i v e t o r e p r o d u c t i v e ( s o r a l ) blade  area  of  can be e s t i m a t e d  s u r f a c e area.  MATERIALS AND METHODS  Laminaria  ephemera was r e p e a t e d l y h a r v e s t e d from each of two s i t e s  the M i l l s P e n n i n s u l a , B a r k l e y Sound, B.C. ( F i g u r e 2.1). presented of  Cable  i n T a b l e 3.1. Beach.  and meets a s o f t bottom punctuated little  wave  action,  from the n o r t h .  Dates of sampling are  An e a s t - f a c i n g promontory forms the western  T h i s r o c k w a l l extends v e r t i c a l l y  but  by rocky  h i g h surge  outcrops.  alon g  boundary  t o a depth of about 5 m, The s i t e  i s subject  to  accompanies winds from the southeast or  The two  study s i t e  sides  comprised a p a t c h r o u g h l y 3 m ,  a t 3 m depth,  limited  by r o c k w a l l , and c h a r a c t e r i z e d by small b o u l d e r s and l a r g e  on a s h i f t i n g ,  cobble  pebbly bottom.  E x e c u t i o n Bay i s s i t u a t e d between the promontories of E x e c u t i o n Rock Nudibranch to  on  Point.  and  The back of the bay c o n s i s t s of rocky pavements extending  a bottom of sand and pebble.  The study s i t e  c o n s t i t u t e d an area of about 5  2 m , at 3 m depth, among cobble and b o u l d e r s . 2 High i n i t i a l each  plant densities  of these two s i t e s  (0.98 per cm ) and  are  d i s c u s s i o n that  made  by  use  of  of the  July,  developmental juvenile (about  cm  extent  of  single  population.  "population"  No  here  genetic  or i n the  follows.  1982.  blade  f o r a twelve week  period  in  April  The sampling p e r i o d a t each s i t e was determined by the  s t a t u s of p l a n t s a t t h a t  sporophytes 1  a term  P l a n t s were h a r v e s t e d from each s i t e through  areal  a l l o w e d the s u b j e c t i v e d e s i g n a t i o n of a l l c o n s p e c i f i c  i n d i v i d u a l s w i t h i n a s i t e as members inferences  small  attained length),  site.  sufficient and  was  Sampling  was  initiated  s i z e f o r taxonomic  continued  until  when  identification  fewer  than  fifty  i n d i v i d u a l s remained w i t h i n the study area.  The  small s i z e of p r e - r e p r o d u c t i v e  compressed of  a i r driven a i r l i f t  sampler.  individuals The a i r l i f t  necessitated  a l l o w e d thorough  the h a r v e s t e d area, without l o s s of i n d i v i d u a l s of  Airlift later  sampling  was  use  smaller  size  of  a  sampling classes.  r e p l a c e d by h a n d - c o l l e c t i o n of p l a n t s i n samples taken  i n the season. 2 Each sample c o n s i s t e d of a l l p l a n t s removed from an a r e a of about  Plants  were  transported  to  the  laboratory  i n mesh bags,  1  m .  and m a i n t a i n e d i n  - 28 -  t r a y s of f l o w i n g seawater. individuals  within  Blade  each  and sorus  sample.  perimeter  Larger  plants  s m a l l e r p l a n t s were p r e s s e d and d r i e d p r i o r of  1.78%  was  calculated  was  were  were  to t r a c i n g .  the mean  of  68  traced  for  traced while  fresh;  correction  factor  A  replicates,  f o r use i n  s t a n d a r d i z i n g s u r f a c e area measurements of p r e s s e d and d r i e d p l a n t s w i t h of  all  those  fresh plants.  F i f t y p l a n t s were randomly s e l e c t e d from surface  area  means of  and  integrating  digitizing  tablet  2 0.01 cm .  Operator  mean of twenty-two  Sorus sites  e x c i s e d from  Total  vegetative  sorus s u r f a c e area were c a l c u l a t e d f o r each p l a n t by  the  area  beneath  the  traced  i n tandem w i t h an LSI-11 computer. accuracy was e s t i m a t e d t o be  perimemters,  using  a  V a l u e s were r e c o r d e d t o  + -0.19%,  calculated  as the  trials.  samples were taken from 5 mature sporophytes  (Cable  zone.  total  each sample.  Beach and E x e c u t i o n B a y ) . each p l a n t , from  from  each of  2  One p i e c e of approximately  the r e g i o n immediately  distal  t o the  study  1 cm  was  transition  P i e c e s of sorus were p r e s e r v e d i n 4% f o r m a l i n s o l u t i o n i n seawater, and  l a t e r s e c t i o n e d i n both l o n g i t u d i n a l plane  were  prepared  microscopically number  and  viewed  and t r a n s v e r s e p l a n e s ; s e c t i o n s from independently.  P r e p a r a t i o n s were examined  f o r d e t e r m i n a t i o n of number of spores per sporangium,  of s p o r a n g i a per u n i t blade  s u r f a c e area.  each  and of  F i v e o b s e r v a t i o n s were made  per p r e p a r a t i o n , on r e p l i c a t e d s e c t i o n s , f o r a t o t a l  of f i f t y  observations per  population.  One-way a n a l y s i s of v a r i a n c e was performed (1969)  subsequent  to  Bartlett's  test  a c c o r d i n g t o Sokal f o r homogeneity  of  and  Rohlf  variance.  T r a n s f o r m a t i o n of v a l u e s p r i o r t o a n a l y s i s was performed when a p p r o p r i a t e , and i s i n d c a t e d i n the t e x t .  - 29  -  RESULTS  Mean v e g e t a t i v e s u r f a c e area at Cable Beach decreased from 293.0 cm April  1982)  t o 116.6  decreased from Individual 1982)  cm  48.4  values  t o 452.4 cm  cm  2  (13 June 1982;  2  (09  April  F i g u r e 3.1).  1982)  to  Mean s o r a l  22.6  cm  9  2  (09 A p r i l  1982);  and from a s o r a l  s u r f a c e area  (13  ranged from a v e g e t a t i v e s u r f a c e a r e a of 0.2  (09  June cm  2  1982).  (09  s u r f a c e area of  April  0.1  cm  2  2 (13  June 1982)  t o 124.4  cm  (09 A p r i l  1982).  s i t e on the f o u r t h sampling date of 05 J u l y  No p l a n t s remained 1982.  Mean v e g e t a t i v e s u r f a c e area at E x e c u t i o n Bay (19  April  1982)  t o 115.7  area d e c l i n e d from 100.6  cm  cm  2  2  (05 J u l y 1982; (19 A p r i l  1982)  at the study  decreased  F i g u r e 3.2). to  40.6  cm  from  687.6  cm  2  Mean s o r a l s u r f a c e  2  (05  July  1982).  2 Individual 1982)  values  t o 999.3 cm  June 1982)  (19 May  t o 245.1  Ninety-two final  2  ranged from a v e g e t a t i v e s u r f a c e area of 0.3  cm  2  1982),  (13 June  and from a s o r a l  ( F i g u r e 3.3).  reproductive  r e p r o d u c t i v e on the f i n a l  smallest  (0.1-100.0  cm  2  of every sample at Cable Beach  ) size class  ( F i g u r e 3.5).  on  sampling of 05 J u l y  Samples from Cable Beach and from E x e c u t i o n Bay  g r e a t e s t percentage  2  (13  the  One-hundred p e r c e n t of the  r e p r o d u c t i v e p l a n t s on the common sampling date of 13 June  The  cm  1982).  sampling date of 13 June 1982  ( F i g u r e 3.4).  (19 A p r i l  s u r f a c e a r e a of 0.7  percent of the sample at Cable Beach was  sample at E x e c u t i o n Bay was  cm  1982  both showed 92%  1982.  fell  within  No p l a n t s remained  the  within  2 the l a r g e s t  (400.1-500 cm  and 13 June  1982).  ) s i z e c l a s s at the l a t e r  sampling dates of  04  May  - 30 -  The smallest  g r e a t e s t percentage of each sample at E x e c u t i o n Bay f e l l size class,  3.6).  among the  second,  third,  and  fifth  size  classes  P l a n t s were found among the l a r g e s t s i z e c l a s s e s (800.1-900.0  2 and 900.1-1000.0 cm ) only on the sampling dates  of 19 May and  At Cable Beach, many p l a n t s among the l a r g e r s i z e c l a s s e s reproductive  at  28  May  1982.  2 p l a n t s exceeded 400.00 cm .  By 05 J u l y 1982, no h a r v e s t e d  were  the  except f o r t h a t sample taken on 28 May 1982, i n which the  g r e a t e s t percentage f e l l (Figure  within  a l l sampling dates  ( F i g u r e 3.7).  (up  to  100%)  Few p l a n t s among the  2 smallest 83.3%  s i z e c l a s s (0.1-100.0 cm ) were r e p r o d u c t i v e  of t h i s s i z e  c l a s s was r e p r o d u c t i v e  a t e a r l y sampling  a t the l a t e s t  dates;  sampling date (13 June  1982). At E x e c u t i o n Bay, a maximum of 100% of the p l a n t s among some l a r g e r classes  were  reproductive  May 1982; F i g u r e 3.8).  even i n the e a r l i e s t  There were  no  samples (19 A p r i l  reproductive  individuals  size  1982 and 19 within  the  2 smallest  size  reproductive the  final  class  (0.1-100.0 cm ) on 19 A p r i l  individuals within this sampling  date  of  05  1982, and the percentage of  s i z e c l a s s remained r e l a t i v e l y July  1982,  low  until  a t which time a l l p l a n t s were  reproductive. The Beach 3.11). June Bay  mean r a t i o of sorus  increased  from  13.2%  I n d i v i d u a l values 1982)  to  s u r f a c e area (09  April  to vegetative  s u r f a c e area a t  1982) t o 19.8% (13 June 1982; F i g u r e  f o r samples from Cable Beach ranged  83.1% (13 June 1982).  i n c r e a s e d from 14.7% (19 A p r i l  Cable  from  Mean v a l u e s f o r samples from  0.3%  (13  Execution  1982) t o 31.7% (05 J u l y 1982; F i g u r e 3.11).  I n d i v i d u a l v a l u e s ranged from 1.9% (28 March 1982) t o 92.2% (05 J u l y 1982).  - 31 -  All  mature  Presumably,  sporangia  observed  contained  16 of these 32 spores were female,  No attempt was made i n t h i s study  M i c r o s c o p i c examination  32  spores  per  sporangium.  and 16 were male (Kain, 1964).  t o determine sex r a t i o of spores.  of p l a n t s from Cable Beach gave a mean  7.72 sporangia per 0.012 cm (n=50; S.D.=0.93). 5 2 4.14 X 10 sporangia per cm .  value  of  This quantity i s equivalent to  F o r p l a n t s from E x e c u t i o n Bay,  a mean v a l u e  of  8.02 sporangia per 0.012 cm (n=50; S.D.=0.77) was o b t a i n e d ; t h i s i s e q u i v a l e n t 5 2 to 4.47 X 10 sporangia per cm .  A n a l y s i s of v a r i a n c e  difference  of sporangia per u n i t l e n g t h f o r p l a n t s from  these  between  two s i t e s .  the  number  showed  no  E s t i m a t e d mean numbers of spores produced were  significant  1.32  X  10  7  2 7 2 spores per cm (Cable Beach), and 1.43 X 10 spores per cm ( E x e c u t i o n B a y ) .  A c o n s e r v a t i v e estimate minimum  mean  soral  of sporophyte  surface  f e c u n d i t y can be made by  combining  area w i t h estimates of spores produced p e r u n i t  area X 0.5.  The r e s u l t i n g f e c u n d i t y e s t i m a t e s g Beach) and 2.90 X 10 spores ( E x e c u t i o n B a y ) .  g 10  are 1.49 X  spores  (Cable  DISCUSSION  Sporophytes c o l l e c t e d from  both  Cable  Beach  and  e x h i b i t e d s e v e r a l c h a r a c t e r i s t i c s which may be expected These i n c l u d e l i t t l e time-to-maturity, population. not  expected  development  and  At l e a s t  high  of  supportive  percentage  of  from  tissues,  reproductive  p l a n t s ; these  relatively plants  tissue  t o sorus  formation.  short  w i t h i n the  are g e n e r a l l y  include a p o t e n t i a l l y  p r e - r e p r o d u c t i v e m o r t a l i t y and a low r e p r o d u c t i v e e f f o r t , judged low mean a l l o c a t i o n of blade  Bay  of semelparous p l a n t s .  two c h a r a c t e r i s t i c s were e x h i b i t e d which  of strongly-semelparous  Execution  high  by r e l a t i v e l y  - 32  The the  development of l i t t l e  plant  thallus,  -  supportive tissue  and of blade  and  i s e v i d e n t from i n s p e c t i o n of  s t i p e c r o s s - s e c t i o n s ( c f . Druehl,  S t i p e s are t h i n and b a r e l y — c o r t i c a t e d , and l a c k mucilage ducts. is  small  with  and  slight  The that  without  Individual estimated  and  IS  were f i r s t  March, 1982;  become r e p r o d u c t i v e .  By May,  sites  sori  had  produced  harvested plants (Execution  Bay),  or  much  A very h i g h plants  sori  all  and  than  that  percentage were  may  the  had  for  and  Small  3.4),  but  Sorus  can  be  ( l e s s than 10 and  at  cm  Execution  estimated an  of  92%;  incipient  (Cable B e a c h ) . to  be  individual  Beach:  5  within  of the  of  the  Sporophyte  a  Execution  initiated  not  both  and  is  population.  to 2 months.  Bay:  100%)  These data  sporophytes  and t h e r e i s no estimate do  had  necrosis  months,  r e p r o d u c t i v e at the end of the season. or 100%  from  and by J u l y , 100%  signs  disappeared  number of p l a n t s w i t h i n a p o p u l a t i o n which maturity.  tissues.  of the p l a n t s h a r v e s t e d  be as short as 1.5  (Cable  season,  indicates  other k e l p s p e c i e s .  at Cable Beach  showed  conservatively  less  within  obs.)  by 24 March, some p l a n t s at Cable Beach  plants  i n d i c a t e , however, t h a t 92%  reproductive  observed  more than 25%  Developmental t i m e - t o - m a t u r i t y  not  (pers.  not measured i n t h i s study,  ( r e : F i g u r e s 3.3  displayed  life-span i s therefore  harvested  stipe  from f i e l d o b s e r v a t i o n of the p o p u l a t i o n s .  14  probably  was  and  tissues.  s t i p e has not been r e p o r t e d f o r any  time-to-maturity  holdfast  cortication  not be h i g h l y d i f f e r e n t i a t e d from blade  area) sporophytes on  are t h i n , w i t h l i t t l e  o c c a s i o n a l f o r m a t i o n of s o r i along the  f o r m a t i o n along the  Bay  Blades  development of medullary  s t i p e t i s s u e s may  blade  haptera.  The  1968).  survive  of do  became  a v a i l a b l e f o r the to  reproductive  - 33 -  F i e l d o b s e r v a t i o n s i n d i c a t e t h a t p r e - r e p r o d u c t i v e m o r t a l i t y may be  high.  in  fact  2 ( l e s s than 2 cm blade s u r f a c e  D e n s i t i e s of very small sporophytes 2  area) were e s t i m a t e d t o be densities  were  4.3  growth to i d e n t i f i a b l e  an  early  in  the  season;  the  period  between  zygote  high  i n the season. formation  and  s u r f a c e area t o v e g e t a t i v e s u r f a c e area can be used as (Pianka and Parker, 1975).  This ratio  averaged from 13% t o 17%, w i t h one o u t s t a n d i n g mean v a l u e of 32%.  Individual  values,  of  in  such  s i z e was not q u a n t i f i e d , but i s p o t e n t i a l l y h i g h .  r a t i o of s o r a l  estimate  cm  never observed among r e p r o d u c t i v e p l a n t s l a t e r  Further, mortality occurring  The  per  reproductive  however,  therefore,  that  transformation  ranged almost  to  effort  from the  sorus  less entire  tissue;  fitness  effort.  i s not  reproductive  Two  tissue  blade  to  is  i n that  explanations  significantly  1%  enhanced  by  1966)  amount  of  reflect  increasing  a  capable  of  low average  generally  low  apparent: 1) t h a t the  allocation  of  t o , say, 90%, and t h e r e f o r e no s e l e c t i v e p r e s s u r e f a v o r s (sensu B e l l ,  which  future  can  viably  survival.  and  However,  profitably the  1980  and  1984;  sporophyte,  i n which  survival  be  produced  without  e x i s t e n c e of such a t r a d e - o f f  between enhanced sorus p r o d u c t i o n and f u t u r e s u r v i v a l ephemeral  relatively  I t appears,  a s s o c i a t e d w i t h sorus p r o d u c t i o n , and t h a t t h i s cost reduces the  sorus  jeopardizing  93%.  immediately  such an i n c r e a s e ; 2) t h a t t h e r e e x i s t s some c o s t Cody,  the  they  are  almost  developmentally  consequently,  v a l u e s of 13% and 17% are unexpected reproductive  than  beyond  seems untenable f o r the the  end  of  the p r e s e n t  r e p r o d u c t i v e episode i s z e r o .  There history  i s some evidence of both w i t h i n - and between-site v a r i a t i o n i n l i f e  traits.  At  decreased w i t h time.  both  Cable  Beach  and  E x e c u t i o n Bay, mean sorus s i z e  T h i s t r e n d i s due t o a small group  of p l a n t s w i t h i n  each  - 34 -  p o p u l a t i o n which grew very q u i c k l y , reached a l a r g e sorus.  These l a r g e and p r e c o c i o u s p l a n t s  which were comprised predominantly  were  size,  absent  and produced a l a r g e from  of p l a n t s of s m a l l e r s i z e  later  samples,  and s m a l l e r sorus  area.  Sporophytes became plant for  a t Cable Beach were r e p r o d u c t i v e e a r l i e r  senescent size  earlier  the season,  concurrent  p l a n t s among the f i n a l and  samples  from  Cable  reproductive  effort  Rock.  The  population  a c h i e v e d a s m a l l e r mean t h a l l u s a  smaller  average  size  Beach; a g r e a t e r percentage of  size,  reproductive  g r e a t e r at  Cable  Beach,  then,  effort,  data, t o d i s c r i m i n a t e between the  Cable  s u r f a c e area t o  Execution  Bay  reproduced  e x h i b i t e d a lower average  than  fecundity  and p h e n o t y p i c e x p r e s s i o n i n d e t e r m i n a t i o n of these s i t e - s p e c i f i c  and  i n the  I t i s i m p o s s i b l e , however,  c o n t r i b u t i o n s of g e n o t y p i c  at  earlier,  and became senescent e a r l i e r  season than the p o p u l a t i o n a t E x e c u t i o n Bay. these  than mean p l a n t  (as the mean r a t i o of s o r a l  at  and Mean  sample was r e p r o d u c t i v e at E x e c u t i o n Bay than at  v e g e t a t i v e s u r f a c e area) was, on average, Wizard  season,  than those a t E x e c u t i o n Bay.  at E x e c u t i o n Bay was g r e a t e r , i n a l l samples,  roughly  Beach;  in  i n the  from  variation  traits.  -  35  -  TABLE 3.1.  CABLE BEACH:  09 A p r i l 1982  EXECUTION BAY:  19 A p r i l  1982  04 May 1982  19 May  1982  13 June 1982  28 May  1982  13 June 1982 05 J u l y  1982  T a b l e 3.1. Dates o f h a r v e s t s made a t e a c h o f two s i t e s , C a b l e Beach and E x e c u t i o n Bay.  - 36 -  CM  E  <_>  o Ci)  OJ  u O  in  400 200 100 50 20h 7  /  1  V time  F i g u r e 3.1. S e m i - l o g a r i t h m i c p l o t o f mean v e g e t a t i v e s u r f a c e a r e a ( f i l l e d c i r c l e s ) a n d mean s o r a l s u r f a c e a r e a ( o p e n c i r c l e s ) , + 1 S . E . , among r e p r o d u c t i v e p l a n t s w i t h i n s a m p l e s c o l l e c t e d f r o m C a b l e B e a c h . (09 A p r i l : n=5; 04 May: n=19; 13 J u l y : n=46; v a r i a b l e n r e s u l t s f r o m t h e v a r i a b l e number o f r e p r o d u c t i v e p l a n t s w i t h i n e a c h s a m p l e o f 50 i n dividuals) .  -  1000 ^  a  37  -  r-  500 200 100  0  o  50 00  20  AV ^ time  F i g u r e 3.2. S e m i - l o g a r i t h m i c p l o t o f mean v e g e t a t i v e s u r f a c e a r e a ( f i l l e d c i r c l e s ) a n d mean s o r a l s u r f a c e a r e a (open c i r c l e s ) , + 1 S . E . , among r e p r o d u c t i v e p l a n t s w i t h i n s a m p l e s c o l l e c t e d from E x e c u t i o n Bay. (19 A p r i l : n=2; 19 May: n=2 8 ; 28 May: n=44; 13 J u n e : n=46; 05 J u l y : n=50; v a r i a b l e n r e s u l t s f r o m t h e v a r i a b l e number o f r e p r o d u c t i v e p l a n t s w i t h i n e a c h s a m p l e o f 50 i n d i v i d u a l s ) .  -  38  -  100  80 §  60  CL  AO 20 h  ><^  V  V time F i g u r e 3.3. Percentage Cable Beach.  of  soral  plants  among s a m p l e s  from  -  39  -  100 80 60  -  AO 20  7-^  ^7-  time  F i g u r e 3.4. Percentage E x e c u t i o n Bay.  of s o r a l  plants  among  samples  from  - 40 -  80 60 40 20  60 c <_>  AO  D-  20  4020-  surface area  (cm2)  F i g u r e 3.5. P e r c e n t a g e o f p l a n t s f a l l i n g w i t h i n 1 0 0 cm s i z e c l a s s e s , f o r three samples from Cable Beach; above: 0 9 A p r i l ; m i d d l e : 04 M a y ; b e l o w : 13 J u n e , 1 9 8 2 .  -  41  -  80604020 -  4020c  20-i  20-  40 20 -  c£ ^ \r r  C?> c £ r $ c £ C?>  \P  & <\Q  C?> c£  ->  surface area (cm') F i g u r e 3.6. P e r c e n t a g e o f p l a n t s f a l l i n g w i t h i n 100 cm s i z e c l a s s e s , f o r f i v e s a m p l e s f r o m E x e c u t i o n Bay; f r o m t o p : 19 A p r i l ; 19 May; 28 May; 13 J u n e ; 05 J u l y , 1982.  -  42  -  100-|  100-, c u  60 -  !_  CU  Q.  20100  n  60207  s urface a r e a  7-  (cm2)  Figure23.7. Percentage of r e p r o d u c t i v e p l a n t s w i t h i n each 100 cm ( s u r f a c e area) s i z e c l a s s , f o r samples from C a b l e Beach. A b o v e : 19 A p r i l ; m i d d l e : 04 May; b e l o w : 13 J u n e , 1982.  -  43  -  100-1 60-  20-  100-i 60 -  20-  100  §  <u  -i  60-  CL  -  20-' 100 60 20-  100" 6020&  ^  ^  ^  c£  c£  surface area (cm2) Figure 3.8. P e r c e n t a g e o f r e p r o d u c t i v e p l a n t s w i t h i n each 100 cm ( s u r f a c e area) s i z e c l a s s , f o r samples from Execut i o n Bay. From t o p : 19 A p r i l ; 19 May; 28 May; 13 June; 05 J u l y , 1982. ?  -  cu  0.6  44  -  r  o >  £  0.4 0.2 J  09 19 APRIL  J  L  04  19 28 MAY  13  05  JUNE  JULY  time  F i g u r e 3.9. Mean r a t i o ( e x p r e s s e d as a d e c i m a l v a l u e ) o f s o r a l s u r f a c e a r e a t o v e g e t a t i v e s u r f a c e a r e a , + 1 S.D., for s a m p l e s f r o m C a b l e B e a c h ( o p e n c i r c l e s ) and f r o m E x e c u t i o n Bay (filled circles).  - 45 CHAPTER 4 ALLOCATION TO ME10SPORE PRODUCTION IN LAMINARIA SETCHELLII  INTRODUCTION  Sporophytes of L a m i n a r i a general  phenology  Chapter 1. that  the  prolonged  According  the  species  i n Barkley  t o the argument presented  iteroparous species w i l l time-to-maturity,  Fecundity number  of  s e t c h e l l i i are p e r e n n i a l and  iteroparous.  The  Sound has been p r e s e n t e d i n  i n Chapter 1,  exhibit a relatively  we  can  predict  low annual f e c u n d i t y ,  and i n c r e a s i n g r e p r o d u c t i v e e f f o r t w i t h age.  among sporophytes  can be  estimated  determination  of the  of spores produced per i n d i v i d u a l , where the number of spores  produced  i s p r o p o r t i o n a l t o the surface area of the sorus. estimated  as  the r a t i o  by  Reproductive  of v e g e t a t i v e t o r e p r o d u c t i v e  e f f o r t can be  ( s o r a l ) blade  surface  area.  MATERIALS AND METHODS  Laminaria from  each  s e t c h e l l i i was r e p e a t e d l y h a r v e s t e d  of  two  sites.  Wizard  Wizard Rock i s a s m a l l , low i s l a n d , to  west.  The northwest shore  but h i g h surge north.  The  B.C.,  and E x e c u t i o n Bay ( r e : F i g u r e  the l o n g a x i s of which runs roughly  2.1). east  accompany  winds  from  the  southeast  or  margin of the i s l a n d extends t o about 8 m depth, where i t  meets a s l o p i n g g r a n i t i c pavement. fringe,  Sound,  of the i s l a n d i s s u b j e c t t o l i t t l e wave a c t i o n ,  and s t r o n g c u r r e n t s rocky  Rock  i n Barkley  L.  from about the 0 m t i d e l e v e l  setchellii  to 4 m depth.  occupies  the  sublittoral  - 46  The  study p o p u l a t i o n comprised  upper-subtidal s i t e was  11.2  margin.  an area of roughly 12 m by 2 m  Estimated  i n d i v i d u a l s per 0.25  -  average m  2  along  d e n s i t y of L. s e t c h e l l i i  (S.D.=1.55), c a l c u l a t e d as the  the  at  this  mean  of  2 10  haphazardly  the study No  placed  0.25  m  quadrats.  A l l conspecific individuals within  s i t e were s u b j e c t i v e l y d e s i g n a t e d as members of a s i n g l e p o p u l a t i o n .  g e n e t i c i n f e r e n c e s are made here by use  of the term " p o p u l a t i o n " here  or  i n the d i s c u s s i o n t h a t f o l l o w s . E x e c u t i o n Bay setchellii  has been p r e v i o u s l y  occurs  described  in  Chapter  2.  Laminaria  along the s u b l i t t o r a l margins of E x e c u t i o n Bay,  along the margins of wash-rocks and p i n n a c l e s i n the c e n t e r of the study  population  consisted  of  at  this  site  was  Estimated  13.2  The  average p l a n t d e n s i t y f o r L.  individuals  c a l c u l a t e d as the mean of 5 haphazardly conspecific  bay.  p l a n t s growing along a 10 m by 2 m l e n g t h of  rocky pavement at the back of the bay. setchellii  as w e l l as  per 2  p l a c e d 0.25  i n d i v i d u a l s w i t h i n the study  m  0.25  m  2  (S.D.=1.48),  quadrats.  Again,  all  area were d e s i g n a t e d as members of a  single population. P l a n t s were h a r v e s t e d beginning  in  October,  1981  from  each  study  site  for  and  course stipe.  classes  were No  during  harvested u n t i l An  undisturbed  sampling  chosen.  month  period  (Execution Bay). Plants  along  removed at the h o l d f a s t or at the j u n c t u r e of the h o l d f a s t  d i s c r i m i n a t i o n was harvesting. a total  made  All  plants  between  Courses  were  of p r e v i o u s l y h a r v e s t e d  areas.  of  different  size  along the course were  i n d i v i d u a l s had been  m width was  chosen  plants  encountered  sample of more than 55  area of at l e a s t 0.5  harvested courses.  12  (Wizard Rock) and November, 1981  For each h a r v e s t , a course p e r p e n d i c u l a r to shore was this  a  obtained.  allowed between s u c c e s s i v e l y  sequentially,  in  order  to  avoid  - 47  -  Samples were r e t u r n e d to the l a b o r a t o r y and water  prior  to  processing.  For each p l a n t , the blade was  s t i p e at the t r a n s i t i o n zone. traced  onto paper.  sori;  if  The  perimeter  D i s t i n c t i o n was  and newly-generated blade present,  tissue.  sori  maintained  of  the  entire  in  flowing  removed from blade  was  made between o l d or r e s i d u a l blade  B l a d e s were examined f o r  were e x c i s e d and  these  perimeters  sea  the  the then  tissue  presence  of  were a l s o t r a c e d .  B l a d e s were d i s c a r d e d a f t e r t r a c i n g .  Fifty vegetative  traced and  plants total  d e s c r i b e d i n Chapter  The  were  soral  randomly surface  area  was  from  each  sample.  Total  c a l c u l a t e d f o r each p l a n t  as  3.  diameter at the base and  measured  chosen  and r e c o r d e d .  The  the t o t a l  l e n g t h of each s t i p e h a r v e s t e d  volume of each s t i p e was  was  c a l c u l a t e d as the volume  2 of a c y l i n d e r (volume=TTr retained  and  immediately  X height). frozen  Basal  for  portions  of  all  stipes  were  l a t e r s e c t i o n i n g , f o r purposes of  age  determination. Sorus samples were taken from 5 r e p r o d u c t i v e  sporophytes from each  study  2 site.  One  p i e c e of approximately  a r e g i o n midway along the f r o n d . s e c t i o n e d and  1 cm  was  e x c i s e d from each i n d i v i d u a l ,  Each e x c i s e d p i e c e was  preserved  from  and  later  examined m i c r o s c o p i c a l l y as p r e v i o u s l y d e s c r i b e d i n Chapter  3.  RESULTS  Mean v e g e t a t i v e from 299.4 cm  2  surface among r e p r o d u c t i v e  (28 January 1982)  d i s c r i m i n a t i o n between age values.  t o 5254.4 cm  or s i z e c l a s s was  2  p l a n t s at Wizard (18 June 1982;  made i n  I n d i v i d u a l v a l u e s among r e p r o d u c t i v e  Rock  ranged  F i g u r e 4.1).  calculating  these  p l a n t s ranged from 55.7  cm  No mean  2  (19  - 48 -  November 1982) on  t o 8136.6 cm  log-transformed  mean v e g e t a t i v e December 1981,  values  these  showed  1982).  significant  difference  January 1982)  19  (p<.001 l e v e l ) i n November  (n=0  from  and n=2,  between-group  Samples  this  analysis  differences  (p<.001 l e v e l ) between Group 1 (12 December 1981 18 June,  and 05 August 1982).  cm  (05 August  2  (18 June 1982)  1982); F i g u r e 4.1).  t o 1202.3 cm  2  cm  2  (28  performed on l o g - t r a n s f o r m e d v a l u e s showed no s i g n i f i c a n t  (p<.001 l e v e l ) between s i x samples 29 A p r i l ,  and 15 March 1982  ranged  4.2).  from  1981).  was  s u r f a c e area to v e g e t a t i v e  1.25%  (18  Analysis  (p<.001  level)  between  samples.  June 1982)  difference  Analysis  of  (18  variance Results  analysis  as noted  surface  June was  showed  of  difference and  above.  area  at  t o 18.54% (19 November 1981;  0.01%  i n the r a t i o of s o r a l Further  1981).  Samples taken 15 October  were o m i t t e d from t h i s a n a l y s i s ,  t r a n s f o r m a t i o n of decimal v a l u e s .  significant  28  January  taken 19 November and 12 December 1981,  I n d i v i d u a l v a l u e s ranged from  November  (19 November  18 June, and 05 August 1982.  Mean r a t i o s of s o r a l Rock  and  I n d i v i d u a l v a l u e s ranged  variance  1981  showed  There  cm  January,  12  1982.  from 0.02  28  and  respectively) within  s u r f a c e areas a t Wizard Rock ranged from 28.1  109.2 2  on  performed  d i f f e r e n c e between samples w i t h i n Group 2.  Mean s o r a l to  of  and Group 2 (29 A p r i l ,  no s i g n i f i c a n t  taken  were excluded  of the small number of i n d i v i d u a l s analysis  differences  18 June, and 05 August  and 15 March 1982  Further  A n a l y s i s of v a r i a n c e  significant  and 28 January, 29 A p r i l ,  samples.  1982)  (05 August  s u r f a c e area between samples  taken on 15 October 1981 because  2  1982)  to  performed a  Figure  44.80%  after  significant  Wizard  (19  arc-sin  difference  s u r f a c e a r e a to v e g e t a t i v e s u r f a c e area of  between-group  variance  showed  (p<.001 l e v e l ) between Group 1 (19 November 1981)  Group 2 (12 December 1981, 28 January, 29 A p r i l ,  18 June, and 05 August  and  1982).  - 49 -  There was  no s i g n i f i c a n t  d i f f e r e n c e between samples w i t h i n Group 2.  The percentage of h a r v e s t e d p l a n t s b e a r i n g from  0%  percent  (15 October 1981)  g r e a t e s t number of s o r a l p l a n t s was August  1982  October 1982  (54%).  from  4.4).  No  these  values.  cm  2  (05 August 1982;  number  of  ranged  F i g u r e 4.3).  found on 12 December 1981  smallest  Rock  The  (34%) and on  s o r a l p l a n t s was  05  found on 15  341.2  cm  2  (25 November 1981)  t o 5026.4 cm  2  (28 May  1982;  Bay  Figure  d i s c r i m i n a t i o n between age or s i z e c l a s s was made i n c a l c u l a t i o n  performed  Individual  on  to  level)  v a l u e s among r e p r o d u c t i v e p l a n t s ranged from  81.9  cm  log-transformed  l e v e l ) between samples.  May  Wizard  surface areas among r e p r o d u c t i v e p l a n t s at E x e c u t i o n  (28 January 1982)  (p<.05  at  (0%) and on 15 March 1982 ( 4 % ) .  Mean v e g e t a t i v e ranged  The  t o 54%  sori  2  (28  values  Further  May  1982).  Analysis  showed a s i g n i f i c a n t  analysis  showed  a  of  of 74.6  variance  d i f f e r e n c e (p<.001  significant  between Group 1 (15 March and 28 October 1982)  difference  and Group 2  (28  1982). 2 Mean s o r a l  1982)  to  from 1.1 variance  s u r f a c e areas at E x e c u t i o n Bay  performed  1981,  a  on l o g - t r a n s f o r m e d  significant  March  no s i g n i f i c a n t  Bay  ranged  values  showed a s i g n i f i c a n t d i f f e r e n c e  d i f f e r e n c e (p<.001 l e v e l ) between Group 1 (25 November 1982)  and Group 2  (28  October  1982).  d i f f e r e n c e between samples w i t h i n Group 1.  The mean r a t i o s of s o r a l Execution  (15  F u r t h e r a n a l y s i s of between-group d i f f e r e n c e s  28 January, 15 March, and 28 May,  There was  cm  2 1116.3 cm (28 October 1982; F i g u r e 4.4). I n d i v i d u a l v a l u e s ranged 2 2 cm (28 May 1982) t o 4206.7 cm (28 October 1982). A n a l y s i s of  (p<.001 l e v e l ) between samples. showed  ranged from 40.5  from  surface 1.74%  area (28 May  to  vegetative  1982)  surface  area  t o 30.48% (28 October  at  1982;  Figure  4.2).  November  Individual  1981).  Analysis  showed a s i g n i f i c a n t analysis  showed  November 1981 May  a  and  1982).  v a l u e s ranged from 0.04% of v a r i a n c e  difference  level)  significant difference  There was  no  1982)  to  83.6%  (25  performed on a r c - s i n t r a n s f o r m e d v a l u e s  (p<.001  28 October 1982)  (28 May  between  samples.  Further  (p<.001 l e v e l ) between Group 1  and Group 2  (28 January, 15 March,  s i g n i f i c a n t difference  (25  and  between samples w i t h i n  28  either  group.  The March  percentage of p l a n t s b e a r i n g s o r i at E x e c u t i o n Bay  1982)  to  48%  (28  October 1982;  s o r a l p l a n t s were found on 28 May the  smallest  number was  no  (34%)  and  found on 15 March 1982  Correlation analysis showed  1982  Figure  (Spain,  1982)  of  4.5). on 20  The  soral  surface  age  Bay  and  at  Execution  c o r r e l a t i o n (p<.001 l e v e l ) between these two Differences  i n the  c o n s i d e r e d to be The  results  of  shape of the b e s t — f i t  important u n t i l the  analysis  indicate  area  showed  each  and  versus  that,  for  versus  a significant positive  parameters ( F i g u r e s 4.6  further  age  Correlation  sample  curve between these two  confirmed by  number of (48%),  parameters.  plants within  Rock  (15  (6%).  s i g n i f i c a n t c o r r e l a t i o n between these two  Wizard  greatest  October 1982  a n a l y s i s of the percentage of r e p r o d u c t i v e at  ranged from 6%  sampling  4.7).  s i t e s i s not  and  sporophytes  p o p u l a t i o n s samples, the p r o b a b i l i t y of becoming r e p r o d u c t i v e  and  analysis. among  increases  the with  age.  Correlation analysis positive  correlation  4.8-4.11).  The  sufficient  magnitude  s t i p e volume.  of  stipe  (p<.001  level)  volume  versus  between  age  these two  c o e f f i c i e n t of d e t e r m i n a t i o n o b t a i n e d by to  allow c o n f i d e n t  These data do  showed  parameters  analysis  p r e d i c t i o n of age  i n d i c a t e , however, t h a t  stipe  significant  by  is  (Figures not  observation  volume  of of  increases  - 51 -  with  age,  and t h i s o b s e r v a t i o n i m p l i e s the occurrence  of e n e r g e t i c processes  which may have importance t o other e n e r g e t i c a s p e c t s of  the  sporophyte  life  history.  A l l mature sporangia observed sex  ratio  smong  spores  is  c o n t a i n e d 32 spores per sporangium.  assumed ( c f . Kain, 1964).  sporangia per l i n e a r centimeter  (n=50; S.D.=0.87)  was  A  A mean v a l u e obtained  1:1  of 7.82  for  samples  5 from For  Wizard  Rock.  This value  i s e q u i v a l e n t t o 4.25 X 10  samples from E x e c u t i o n Bay,  centimeter  (n=50;  S.D.=1.44)  a  mean  value  of  2 sporangia per cm .  6.36  spores  per  linear  was o b t a i n e d ; t h i s i s e q u i v a l e n t t o 2.81 X 105  2 sporangia  per  significant  cm .  Analysis  difference  (p<.001  of  variance  level)  in  showed number  that of  there  exists  a  sporangia per l i n e a r  centimeter between samples from Wizard Rock and E x e c u t i o n Bay. A c o n s e r v a t i v e estimate combining  minimum  mean  of annual  soral  sporophyte  surface  fecundity  can  be  made  by  area w i t h estimates of the number of  spores produced per u n i t s u r f a c e area X (0.5). The r e s u l t i n g estimates are 8 8 X 10 spores (Wizard Rock) and 1.80 X 10 spores ( E x e c u t i o n B a y ) . This  1.91  f o r m u l a t i o n assumes t h a t each p l a n t s u r v i v i n g t o reproduce equivalent  to  the  reproductive period. estimate  precludes  observed  minimum mean s o r a l  The l a c k of a g e - s p e c i f i c i t y assignment  of  any  produces  a  sorus  s u r f a c e area i n at l e a s t one i n the c a l c u l a t i o n  reproductive  value  of  to  this  estimated  fecundity.  DISCUSSION  Among the p o p u l a t i o n s s t u d i e d , there e x i s t s a s t r o n g s e a s o n a l i t y processes  of  blade  generation  and  stipe-holdfast  generation,  to  the  though the  - 52  precise  t i m i n g of these  tissues  are  p r o c e s s e s may  generally  and  and A p r i l is  in  E x i s t i n g blades  of  iteroparous  effort  sorus  low  effort,  until  of f i r s t  the  apparent season.  year.  blade  occur  haptera,  throughout the  i n the f a l l  These of in  where  supportive comparison  at two  sites i n  year,  (Wizard  Barkley  but  Rock)  include  with  maximum  delayed  values  setchellii  is  maturity,  individual  as the r a t i o  generally  though i n d i v i d u a l s are capable first  and  expected  reproductive  for  i s estimated  show  of  area.  reproduction i n Laminaria  of  Sound  those  t i s s u e s , and an average  reproductive e f f o r t  c o r r e l a t i o n between age  i n March  (Execution Bay).  i n the e a r l y f a l l  characteristics  Beyond the age  stipe  (Execution Bay).  setchellii  second or t h i r d y e a r ,  the f i r s t  New  are f o l l o w e d by  c h a r a c t e r i s t i c s which are c o n s i s t e n t w i t h  species.  is  are sloughed  s u r f a c e area to v e g e t a t i v e s u r f a c e  Age  in  of L a m i n a r i a  development  which  reproductive  Sorus p r o d u c t i o n may  and e a r l y w i n t e r  history  substantial  i n i t i a t i o n and expansion  d e t e r i o r a t e and  Populations life  blade  summer months (Wizard Rock) and  and i n the l a t e f a l l  several  site-specific.  i n c r e a s e i n g i r t h , and by p r o d u c t i o n of new  (both s i t e s ) .  greatest  somewhat  i n i t i a t e d i n October and November (Wizard Rock) or i n  January ( E x e c u t i o n B a y ) ; elongation  be  -  reproduction,  of  delayed  reproduction  there  exists  no  the magnitude of sorus p r o d u c t i o n i n any  There does e x i s t , however, a p o s i t i v e c o r r e l a t i o n between age  and  the  p r o b a b i l i t y of sorus p r o d u c t i o n w i t h i n a season.  and  The  o b s e r v a t i o n s of a p o s i t i v e  of  no  correlation  a l l o c a t i o n of r e s o u r c e s growth  may  constitute  between t o these  c o r r e l a t i o n between age age  and  fecundity,  to f u n c t i o n s .  consevative  and  suggest  stipe  volume,  differential  That i s , s t i p e maintenance  and  p h y s i o l o g i c a l f u n c t i o n s which p r e d i c t a b l y  demand a p r o p o r t i o n of annual r e s o u r c e s , whereas f e c u n d i t y , w i t h no  observable  - 53 -  age-dependent  correlation  be yond  the  o c c a s i o n a l l y demand r e s o u r c e a l l o c a t i o n , individual Implicit  age  and  perhaps  a  age  this  may  response  not be a j u s t i f i a b l e  to  other  of  within-plant  tissues i s  p r o d u c t i o n i s minimal  The  greatest  during  March  of  signals.  competition f o r  f o r the k e l p s , i n which  pigmented  of p h o t o s y n t h e s i s and n u t r i e n t a s s i m i l a t i o n .  and h o l d f a s t  a  (unidentified)  assumption  s t i p e , h o l d f a s t , b l a d e , and sorus t i s s u e s are a l l capable  r e p r o d u c t i o n , may only  t h i s a l l o c a t i o n being independent  i n t h i s argument i s the e x i s t e n c e  resources;  of f i r s t  and  potentially  G e n e r a t i o n of new s t i p e  and  April;  observed  sorus  d u r i n g these months.  r a t i o of sorus s u r f a c e area t o v e g e t a t i v e s u r f a c e area can be used as  measure  of r e p r o d u c t i v e e f f o r t  (Pianka and P a r k e r , 1975).  The mean r a t i o s  (Wizard Rock: 18.54%; E x e c u t i o n Bay: 30.48%) are small when compared w i t h corresponding 83.63%).  maximum  allocation  physiologically  Values error  i n d i v i d u a l v a l u e s (Wizard Rock: 44.80%; E x e c u t i o n Bay:  T h i s i n d i c a t e s that reproductive e f f o r t  actual  to  sorus  production  obtained f o r i n d i v i d u a l in  the d i s c r e t e  and  values  reflect  an  sorus p r o d u c t i o n .  mean  sampling  sorus p r o d u c t i o n was not measured through  underestimate  i s g e n e r a l l y low,  is  less  sorus  time  instantaneous  production  which  may  f o r any measurement  single  that is  and  should  reflect That i s ,  individual; may  I t should be noted, however, t h a t  area as a f r a c t i o n of v e g e t a t i v e s u r f a c e area  values.  that  of a continuous v a r i a b l e .  s u r f a c e area a l s o c o n s t i t u t e s a continuous v a r i a b l e .  error,  than  and  possible.  inherent  resulting  the  in  fact  vegetative  E x p r e s s i n g sorus s u r f a c e therefore  reduce  this  and v a l u e s o b t a i n e d are c o n s i d e r e d t o be s t r o n g l y i n d i c a t i v e of a c t u a l  - 54 -  Reproductive year,  and  only  i n d i v i d u a l s were one  reproductive plants. and  between  sample  found  (Wizard  among Rock:  populations 15  Abundance of r e p r o d u c t i v e p l a n t s v a r i e d both  populations.  less  abundant  in  the f a l l  and s p r i n g .  one  (Wizard  populations  of  Rock,  individuals  h i g h p r o p o r t i o n s of a congeneric  f o r any  1982)  and  in  and  the  reproductive  fall  data were c o l l e c t e d p r e c l u d e s  of s i t e - s p e c i f i c  magnitude of r e p r o d u c t i v e  genotypic  above.  It  is  events  differences  varied  impossible  d i f f e r e n c e s and phenotypic traits.  between  from these  plasticity  among  reproductive  confident  here.  prediction  annually.  c h a r a c t e r i s t i c s among p o p u l a t i o n s of L a m i n a r i a  discussed  found  I t i s possible,  the summed p r o p o r t i o n of  the t o t a l number of i n d i v i d u a l s r e p r o d u c i n g  There i s evidence  a l l samples  contrasts sharply  individuals  annual s p e c i e s ( r e : Chapter 3 ) .  setchellii,  in  annual p e r i o d i s g r e a t e r than the v a l u e s o b t a i n e d  The manner i n which these  specific  (May  05 August 1982: 5 4 % ) . T h i s r e s u l t  however, t h a t f o r L a m i n a r i a  history  1981),  At E x e c u t i o n Bay, r e p r o d u c t i v e  p r o p o r t i o n of r e p r o d u c t i v e p l a n t s was l e s s than 50%  w i t h the observed  of  spring  (December  1982).  The but  seasonally  At Wizard Rock, s o r a l p l a n t s were most abundant i n  p l a n t s were most abundant i n the l a t e (October  the  October 1981) c o n t a i n e d no  summer months (June and August 1982) and i n the w i n t e r were  throughout  in  expression  setchellii.  the  two  of  life  Timing and  populations,  as  data t o d i s t i n g u i s h between  i n the d e t e r m i n a t i o n  of  site-  -  55 -  TABLE 4.1.  WIZARD ROCK:  15 O c t o b e r 1981  EXECUTION BAY:  25 November 1981  19 November 1981  28 J a n u a r y 1982  28 J a n u a r y 1982  15 March 1982  29 March 1982  28 May 1982  18 June 1982  18 O c t o b e r 1982  05 August 1982  T a b l e 4.1. Dates o f h a r v e s t s made a t each o f two s i t e s , W i z a r d Rock and E x e c u t i o n Bay.  - 56 -  1000  4  A  CM  E  O  CD  (_>  o  100  f  3 01  t  Co  time  F i g u r e 4.1. Semi-logarithmic p l o t o f mean v e g e t a t i v e surf a c e a r e a ( o p e n c i r c l e s ) a n d mean s o r a l s u r f a c e a r e a (fill e d c i r c l e s ) , + 1 S . E . , among r e p r o d u c t i v e p l a n t s w i t h i n samples c o l l e c t e d from W i z a r d Rock. (19 N o v . : n=5; 12 D e c : n=17; 28 J a n . : n=4; 29 A p r i l : n=5; 18 J u n e : n=19; 05 A u g . : n=27; v a r i a b l e n r e s u l t s f r o m t h e v a r i a b l e number o f r e p r o d u c t i v e p l a n t s w i t h i n e a c h s a m p l e o f 50 i n d i v i d u a l s ) .  - 57 -  0.6-1  3  a >  0.4  E  o  T3  o  -  0.2  '  7 7 7  —7  41 7  o 7  I  7  A  7  0  „-  cf  time  Figure 4.2. Mean r a t i o ( e x p r e s s e d as a d e c i m a l v a l u e ) o f s o r a l surface area to vegetative surface area, + 1 S.D., f o r s a m p l e s f r o m W i z a r d Rock ( o p e n c i r c l e s ) and Execution Bay (filled circles).  -  58  -  60-,  I  AOH  CL  20A  *  *?> 1981  O  ^  / ^  / /  4?  1982 time  Figure Wizard  4.3. Percentage Rock.  of  soral  plants  among  samples  at  -  59  -  5000 r d> rsi  E 1000  o v.  o <_> O"  Z3  100  •>  -7  time  F i g u r e 4.4. S e m i - l o g a r i t h m i c p l o t o f mean v e g e t a t i v e surface area ( o p e n c i r c l e s ) a n d mean s o r a l s u r f a c e a r e a ( f i l l e d c i r c l e s ) , + 1 S.E., among r e p r o d u c t i v e p l a n t s w i t h i n samples c o l l e c t e d from Execution Bay. (25 Nov.: n=13; 28 J a n . : n = 8 ; 15 M a r c h : n = 3 ; 2 8 M a y : n = 1 7 ; 28 O c t . : n = 2 4 ) .  -  ~  60  -  4(H  o  S. 20 H -7-  —7  7  7  ^ 1981  ^  7  7"  7  *>V  *°  1982 time  F i g u r e 4.5. Percentage E x e c u t i o n Bay.  of  soral  plants  among  samples  from  -  61  -  F i g u r e 4.6. B e s t - f i t c u r v e g e n e r a t e d by c o r r e l a t i o n of p e r c e n t a g e of r e p r o d u c t i v e p l a n t s v e r s u s age, f o r f r o m W i z a r d Rock.  analysis samples  -  62  -  age  F i g u r e 4.7. Best-fit line g e n e r a t e d by c o r r e l a t i o n o f p e r c e n t a g e o f r e p r o d u c t i v e p l a n t s v e r s u s age, f o r from E x e c u t i o n Bay.  analysis samples  - 63 -  F i g u r e 4.8. B e s t - f i t l i n e g e n e r a t e d by c o r r e l a t i o n analysis o f s t i p e v o l u m e v e r s u s age a t W i z a r d R o c k , 05 A u g . 1982.  -  64  -  F i g u r e 4.9. B e s t - f i t l i n e generated o f s t i p e v o l u m e v e r s u s age a t W i z a r d  by c o r r e l a t i o n analysis R o c k , 18 Nov. 1 9 8 2 .  -  F i g u r e 4.10. Best-fit of s t i p e volume v e r s u s  65  -  l i n e g e n e r a t e d by c o r r e l a t i o n age a t E x e c u t i o n Bay, 28 O c t .  analy 1982.  -  66  -  F i g u r e 4.11. B e s t - f i t l i n e g e n e r a t e d by c o r r e l a t i o n o f s t i p e v o l u m e v e r s u s age a t E x e c u t i o n B a y , 10 Nov.  analysis 1982.  - 67 -  CHAPTER 5 AGE STRUCTURE AMONG POPULATIONS OF LAMINARIA SETCHELLII  INTRODUCTION  Among p o p u l a t i o n s reproduction increase.  and  of  perennial  survivorship  organisms,  ultimately  determine  Q u a n t i f i c a t i o n of the r a t e of i n c r e a s e  these a g e - s p e c i f i c p r o c e s s e s are observable. i s therefore  a crucial  first  age-specific  processes  the p o p u l a t i o n  consequently  of  r a t e of  demands  that  I d e n t i f i c a t i o n of i n d i v i d u a l age  step i n the d e t e r m i n a t i o n  of p o p u l a t i o n  rate  of  ' r ' , or i n s t a n t a n e o u s r a t e  of  increase.  For  the purposes of p o p u l a t i o n  increase,  projection,  may be c a l c u l a t e d as the n a t u r a l l o g a r i t h m  age-structured  m a t r i x ( L e s l i e , 1945).  the age d i s t r i b u t i o n of the p o p u l a t i o n age  Such m a t r i x  Leslie,  Age  individual (1984)  to age.  have  demand  1980;  Caughley  that  that  and  this  Birch,  1945).  distributions  principally  formulations  be known, and u s u a l l y r e q u i r e  d i s t r i b u t i o n i s s t a b l e (Michod and Anderson,  1971;  of the e i g e n v a l u e of the  the  among  lack  algal  of  However, K a i n  an  populations adequate  (1963),  are  largely  criterion  Novaczek  used the c o n c e n t r i c r i n g s v i s i b l e  (1981),  unknown,  due  by which t o determine and  Dayton  et.al.  i n the s t i p e s of some k e l p s i n  order  t o determine age; c o r r e l a t i o n a l evidence only has been used t o show that  such  rings  population  are  annual  in  formation.  Estimates  of i n d i v i d u a l age and of  age d i s t r i b u t i o n f o r L a m i n a r i a s e t c h e l l i i have not been r e p o r t e d i n  the l i t e r a t u r e .  The present  study d e s c r i b e s  the age d i s t r i b u t i o n of L a m i n a r i a  - 68 -  setchellii  at two s i t e s i n B a r k l e y  Sound, Vancouver I s l a n d , B.C.  MATERIALS AND METHODS  S i z e c l a s s frequency repeated, Laminaria Bay.  non-destructive setchellii  Estimated 2  measurements  at each of two study  average  p l a n t s per .025 m quadrats).  by b a s a l diameter  density  m, at about 3 m depth.  m,  at  2  a  to 92 i n d i v i d u a l s f o r the study  Wizard  were  series  of  population  of  and  Execution  haphazardly  placed  0.25  s i t u a t e d on an outcrop approximately  at  diameter  of  s i t u a t e d on an outcrop  Execution  to  Bay  primarily  a l l identifiable  identifiable)  from the s l i g h t  122  was  7.4  p l a c e d 0.25 m  approximately  2  1982.  2.5 m X  p e r i o d of 25 August 1981 t o 02 November  plastic  to the mearest m i l l i m e t e r .  (therefore,  m  2.5 m X 2  2 1  individuals  of  1982.  Laminaria  at i n t e r v a l s of about  Vernier  calipers.  Values  Measurement e r r o r was e s t i m a t e d t o  be not more than 6.77%, c a l c u l a t e d as the mean of 20 repeated measurements tagged  8.4  Observed t o t a l p o p u l a t i o n s i z e ranged from 75  Measurements were made u s i n g  recorded  Rock  a  p o p u l a t i o n at Wizard Rock was  s e t c h e l l i i w i t h i n each p o p u l a t i o n was measured. I n s i t u , s i x weeks.  single  ( c a l c u l a t e d as the mean of f i v e haphazardly  The p o p u l a t i o n was  basal  on  in  p e r i o d of 25 August 1981 t o 18 November  a depth of about 2.5 m.  The  the  average d e n s i t y of the p o p u l a t i o n  per 0.25 m  quadrats).  sites.  estimated  Observed t o t a l p o p u l a t i o n s i z e ranged from 99  i n d i v i d u a l s f o r the sampling  plants  made  ( c a l c u l a t e d as the mean of 5  The p o p u l a t i o n was  Estimated  of  was  individuals.  eccentricity  of  the  This error quantity Laminaria  setchellii  on  results stipe.  Success i n l o c a t i n g and measuring each p l a n t w i t h i n the p o p u l a t i o n at a s i n g l e o b s e r v a t i o n time was 96.1%, c a l c u l a t e d as the mean of 4 s e q u e n t i a l  trials.  - 69 -  All  p l a n t s remaining among the study p o p u l a t i o n s at both study s i t e s were  harvested  in  November  p l a n t was measured. for  later  1982.  The b a s a l p o r t i o n of each s t i p e was  sectioning.  Age  determined by c o u n t i n g b a s a l Each  s t i p e was  I n the l a b o r a t o r y , the b a s a l diameter of each and  frozen  c l a s s frequency among the sampled p o p u l a t i o n s was stipe rings i n cross section  s e c t i o n e d at a d i s t a n c e of l e s s than 0.5  E n t i r e c r o s s s e c t i o n s were cut by hand, and dissecting  retained  these  (re:  Appendix  cm from the h o l d f a s t .  were  examined  beneath  microscope u s i n g a combination of t r a n s m i t t e d and r e f l e c t e d  The maximum number of annual growth  A).  r i n g s were counted and r e c o r d e d  a  light.  for  each  c l a s s f r e q u e n c i e s were determined f o r one a d d i t i o n a l p o p u l a t i o n  each  harvested plant.  Age at  Wizard Rock and a t E x e c u t i o n Bay.  made between 19 November 1981 25  November  1981  and  h a r v e s t i n g methods). number at  28  Repeated h a r v e s t s of 50 p l a n t s each were  and 23 September 1982 October  1982  a single  (Execution  S t i p e s of a l l i n d i v i d u a l s  of r i n g s were counted, as above.  (Wizard Rock), and between  were  Bay;  r e : Chapter 4 f o r  sectioned  and  maximum  Data o b t a i n e d from r e p e a t e d h a r v e s t s  s i t e were p o o l e d i n groups of 150-200, by  date  of  harvest,  for  purposes of a n a l y s i s .  RESULTS  S i z e c l a s s d i s t r i b u t i o n by 2 mm for  a  population  b a s a l diameter increments was  at W i z a r d Rock ( F i g u r e 5.1).  Diameters ranged from 1.0  (18 March, 07 J u l y , 18 November 1982)  t o 28.0  72%  each sample f e l l  of  classes.  the  plants  within  For the f i r s t  w i t h i n the 17-18  mm  within  t h r e e samples,  mm  determined  (18 March 1982).  More  among the 12-24  mm  the g r e a t e s t percentage of p l a n t s  s i z e c l a s s e s ; t h i s peak s h i f t e d t o the 19-20  mm  size  mm  than size fell class  - 70 -  for  a l l but one  sample taken a f t e r 29 October  1981.  The percentage of p l a n t s f a l l i n g w i t h i n the s m a l l e s t basal  diameter)  period. 07  may  be  This quantity  July  1982),  some  (Fig.  i n c r e a s e d from 0%  (29 October 1981)  and decreased a g a i n to 4%  5.2).  Seventy  to  that  of  the  p o p u l a t i o n on 18 November  The age pooled  in  (18 November 1982).  in  The  size  shape  class  of the age  first  Size class determined  for  pooled  Similarly,  distribution a  ranged from 1.0 mm No  single  harvests  for  from  Wizard  group  (19 November 1981  population  26  were  single  11.5%  at  through 15 March (29 A p r i l  by at  11  through  23  first  group.  increments Execution  (11 December 1981,  age  1982)  the minor peak of 8% at f i v e y e a r s i n the  of  2  Bay  ( F i g . 5.4).  25 J u l y 1982)  mm  basal  t o 28.0  mm  diameter  was  S t i p e diameter (02  November  s i z e c l a s s comprised more than 20% of the p o p u l a t i o n , and no  The percentage of p l a n t s w i t h i n the 1-2 mm August,  is  the same  Rock  No  The peak of  c o n s i s t e n t peak s i z e c l a s s e s were apparent w i t h i n t h i s  (25  November  1982.  group s h i f t e d t o 9% at s i x y e a r s i n the second  1982).  obtained  at 12 y e a r s i n the second p o o l e d group  1982).  class  distribution  two groups a c c o r d i n g t o date of h a r v e s t ( F i g . 5.3).  s h i f t e d t o 12.5% September  The age  and  of age 8-14 y e a r s .  class  distribution  class d i s t r i b u t i o n s f o r eight  the  mm  (11 June  determined on 18  c l a s s comprised more than 12.5% of the p o p u l a t i o n . years  t o 11%  p e r c e n t of the p o p u l a t i o n was  F i f t e e n p e r c e n t were 1-2 y e a r s . similar  (1-2  i n d i c a t i o n of r e c r u i t m e n t d u r i n g the sampling  d i s t r i b u t i o n f o r t h i s p o p u l a t i o n at Wizard Rock was 1982  size class  September, 29 October 1981)  and decreased a g a i n t o 1%  (16 October 1982).  population.  size class increased  from  t o 11% (18 March, 25 J u l y The  age c l a s s  0%  1982),  distribution  for  this  population  5.5).  at  Execution  The pooled  determined  age  groups a c c o r d i n g t o date of sampling  the  1-5  year  age  d i s t r i b u t e d between the 6-14 May  the 1-6  through 28 October y e a r age  y e a r age  t h r e e y e a r s of age,  (Fig.  and 9% were  c l a s s d i s t r i b u t i o n s f o r seven h a r v e s t s made at E x e c u t i o n Bay  i n two  among  on 10 November 1982  age.  p o o l e d sample (25 November 1981  (28  was  Seventeen p e r c e n t of the p o p u l a t i o n was  ten y e a r s of  was  Bay  ( F i g . 5.6).  through 15 March 1982)  83% of  c l a s s e s , w i t h the remaining  y e a r age  classes.  c l a s s e s ; the remaining  the  first  population  seventeen  For the second  1982), 70% of the p o p u l a t i o n was  For the  were  percent  pooled  samples  d i s t r i b u t e d among  30% were d i s t r i b u t e d  among  the  7-17  diameter  does  c l a s s d i s t r i b u t i o n of the p o p u l a t i o n .  Size  classes.  DISCUSSION  S i z e c l a s s d i s t r i b u t i o n of L a m i n a r i a not  necessarily  reflect  c l a s s frequency may, and  the  the age  however, r e f l e c t  frequencies  of  s e t c h e l l i i by  basal  populational transitions  the s m a l l e r s i z e c l a s s e s may  through  p r o v i d e an estimate of  r e c r u i t m e n t i n t o a p o p u l a t i o n , when repeated measurements are made. class  distributions  presented  for  4  s i m i l a r between p o p u l a t i o n s a t a s i n g l e bimodal  age  site,  at  The  occur  nor between s i t e s .  age  s t a b l e age  distribution  (sensu  Lotka,  The  1922)  following  at  an  has  d i s t r i b u t i o n r e q u i r e s , by d e f i n i t i o n ,  disturbance  (Lotka,  1922;  d i s t r i b u t i o n i s i n t u i t i v e l y u n s t a b l e i n t h a t an age frequency  age  2 s i t e s were n e i t h e r  d i s t r i b u t i o n i s s e l f - p e r p e t u a t i n g , and t h a t r e v e r s i o n t o such will  The  roughly  c l a s s d i s t r i b u t i o n s e x h i b i t e d by these p o p u l a t i o n s i n d i c a t e t h a t  the normal or s t a b l e achieved.  populations  time,  intermediate  age  cannot  1956). class  generate  a The  not  t h a t the  age  distribution bimodal  exhibiting  an age  been  a  age low-  c l a s s of g r e a t e r  frequency of  0%  at a l a t e r age.  For example, at Wizard Rock ( F i g . 5.2),  among the 3 y e a r age  the 12 y e a r age  Two  give r i s e  c l a s s , under c o n d i t i o n s of  p r o c e s s e s may  fluctuations  c l a s s cannot  in  account  sporophyte  f o r the or  stability.  observed  gametophyte  turn,  t o a frequency of 14% among  age  distributions.  fecundity  variable  may  numbers of  zygotes  and,  Comparison  of  very h i g h numbers of spores produced  the  in  the s m a l l numbers of r e c r u i t s observed however, produced  support by a  this  argument.  population  is  numbers  within  these  Specifically,  not  a frequency  likely  to  of  limit  produce annual  variable recruits.  ( r e : Chapter 4) w i t h  populations  the  Annual  does  not,  h i g h number of recruitment  spores  into  that  population.  I t i s more l i k e l y episodic  recruitment  and  demonstrated  (Kirkman,  recruitment  beneath  may  t h a t the observed age variable  1981;  Pearse  d i s t r i b u t i o n s are the product  s u r v i v o r s h i p among r e c r u i t s . and  Hines,  1979;  window  of  space  absence of the normal age  K a i n (1971; 1963) Laminaria  hyperborea  distribution.  and  fourth  and  the  recruitment the the  d i s t r i b u t i o n among these p o p u l a t i o n s .  has  reported  in  age  distributions  the North A t l a n t i c .  Dayton  year  size  s t r u c t u r e between the p o p u l a t i o n s s t u d i e d , and  et.al.  classes  for  populations  The r e p o r t e d age show no evidence  in California  are most abundant.  The  of  distributions of the  normal  (1984) have r e p o r t e d a weakly bimodal  d i s t r i b u t i o n f o r a population Laminaria s e t c h e l l i i first  that  f a c t o r s are s u f f i c i e n t t o e x p l a i n both  e x h i b i t no s i m i l a r i t y between p o p u l a t i o n s , and age  Patch  a v a i l a b i l i t y would t h e r e f o r e determine  success w i t h i n a canopy; these two observed d i f f e r e n c e s i n age  1978a)  Successful recruitment  depend upon the c r e a t i o n of n e w l y - a v a i l a b l e space.  temporal  I t has been  Lobban,  an e s t a b l i s h e d canopy i s minimal.  of  i n which  data of K a i n  age the  (1971;  1963)  and of Dayton e t . a l .  study  f o r Laminaria  argument proposed  (1984) are c o n s i s t e n t w i t h data  setchellii  obtained  i n B r i t i s h Columbia; Rain's  in  this  data support the  above c o n c e r n i n g s a l t a t o r y r e c r u i t m e n t i n L a m i n a r i a .  Absence of the normal age d i s t r i b u t i o n among the p o p u l a t i o n s s t u d i e d does not  necessarily  number  of  imply  that  the  embryosporophytes  sufficient  to  entirely  p o p u l a t i o n s are d e c l i n i n g i n s i z e .  produced  replace  that  within same  a  population  population  each  (and  I f the year  is  estimates  of  meiospore p r o d u c t i o n i n d i c a t e t h a t t h i s i s p l a u s i b l e ) , then the p o p u l a t i o n may experience  no decrease  i n size.  One can p o s t u l a t e t h a t the  number  of  embryosporophytes  initiated  exceeds the number of r e c r u i t s s u r v i v i n g t o b e g i n the second y e a r .  I f this i s  t r u e , then the p o p u l a t i o n s s t u d i e d may best be d e s c r i b e d by a Deevey Type s u r v i v o r s h i p curve.  Williams'  discussion  a  very  low  makes the important  rate  of  offspring  p o i n t t h a t such  may not, i n f a c t , behave a c c o r d i n g t o Markovian dynamics.  Markovian  demand,  each  strictly,  that  the  sum  of  the  elements  of  at  the system ( p o p u l a t i o n ) a t time T+l i s p r e d i c t a b l e from time T+0.  If a  system  proves  to  be  non-Markovian  c o n v e n t i o n a l m a t r i x f o r m u l a t i o n s are not a p p l i c a b l e . of  non-Markovian  particular,  and  behavior to  the  to  the  kelp l i f e  s i z e a t time T+l i s not determined at  time  T+0,  then  p r o c e s s e s which cannot  the  dynamics history  of  systems dynamics  column i n the  a p p r o p r i a t e L e s l i e - t y p e m a t r i x e q u a l s one, and f u r t h e r assume t h a t of  III  W i l l i a m s (1975) has d i s c u s s e d the r a m i f i c a t i o n s of a v e r y  h i g h r a t e of gamete p r o d u c t i o n coupled w i t h survival.  far  the  state  the observed  state  in  behavior,  An important Laminaria  then  consequence  setchellii  in  i n general, i s that i f population  by the l i f e  history  parameters  p o p u l a t i o n dynamics may be the r e s u l t  be e s t i m a t e d a c c o r d i n g t o e x i s t i n g models.  observable  of s t o c h a s t i c  -  74  -  25 AUG 81 20  20  20  26 SEPT 81  29 OCT 81  c  _• 20  ~  c  20  H DEC 81  11 FE B 82  o CL  20  20  20  20  18 MAR  82  II J U N E 82  07 J U LY 82  02 SEPT 82  20  2  8 mm  F i g u r e 5.1. ten r e p e a t e d  U base  20  26  diameter  S i z e c l a s s d i s t r i b u t i o n by b a s a l s a m p l e s a t W i z a r d Rock.  diameter f o r  -  F i g u r e 5.2.  Age  75  class distribution  -  at Wizard  R o c k , 18  Nov.  1982.  - 76 -  F i g u r e 5.3. Age c l a s s d i s t r i b u t i o n among e a c h o f two p o o l e d samples from W i z a r d Rock. A b o v e : November, D e c e m b e r , 19 81, a n d J a n u a r y , M a r c h , 19 82; b e l o w : A p r i l , J u n e , J u l y , S e p t e m ber, 1982.  77  -  20  20  20  20 c  CD  £  CD Q_  25 A U G  -  81  81  26 S E P T  2 9 0 C T 81  11 D E C  81  18 M A R  82  20 A P R  82  20  20  20  25 J U L Y 82  1 20  20 -  15 S E P T  10 NOV  2  I  I  I82  82  I  I—T  K 20 mm b a s e d i a m e t e r 8  F i g u r e 5.4. Size class distribution r e p e a t e d s a m p l e s a t E x e c u t i o n Bay.  by  basal diameter  26  for  nine  -  c  -  20  u a>  CL  78  1  —1—1  2  A  6  — | — i  8  10  ,  12  ,  ,  U  age F i g u r e 5.5. Age 10 Nov. 1982.  class  distribution  at  Execution  Bay,  20 c  CD u  —i—i—i—i—i—r—i—,—,  CD  °- 20 —  2  4  6  8  10  12  14  16  F i g u r e 5.6. Age c l a s s d i s t r i b u t i o n among each o f two p o o l e d samples from E x e c u t i o n Bay. Above: November, 1981, and J a n u a r y , M a r c h , 1982; below: May, J u l y , Septemeber, and O c t o b e r , 1982.  - 80  -  CHAPTER 6 GENERAL DISCUSSION  A s y n t h e t i c d i s c u s s i o n of r e s u l t s gained from species  suffers  from  d i s s i m i l a r taxa. study  problems  of  i n v e s t i g a t i o n of  congeneric  s i m p l i f i c a t i o n i n h e r e n t i n comparison of  However, the h y p o t h e s i s f o r m u l a t e d f o r the purposes  allowed the t e s t i n g of three p r e d i c t i o n s put f o r t h i n Chapter  w i l l be  addressed  1.  of  this  1.  These  i n turn.  Estimated fecundity  (as  meiospore  production)  was  not  different  o  between  the two  s p e c i e s (L. ephemera: 1.49  ( E x e c u t i o n B a y ) ; L. s e t c h e l l i i : 1.91 (Execution fecundity sporic  Bay)).  This  result  may  is  10  contribution  (1931) has  (Cable Beach) and 2.90  (Wizard  8  Rock)  and  1.80  I t should be  t o o v e r a l l f i t n e s s may statistical  noted,  than  same  10  8  that  be v e r y d i f f e r e n t between the differences  d i s c u s s e d , o f f s p r i n g produced  the  10  X  however,  in  fecundity.  e a r l y i n the p a r e n t s '  be more v a l u a b l e (e.g. make a g r e a t e r c o n t r i b u t i o n t o p o p u l a t i o n  increase)  X  c o n t r a r y t o the p r e d i c t i o n of i n c r e a s e d  i n the semelparous sporophyte.  s p e c i e s , even i n the absence of Fisher  X  X 10  o  number of o f f s p r i n g produced  later  two As  lifetime rate  of  i n the p a r e n t s '  lifetime.  On t h i s b a s i s , one might predict a greater ' r ' f o r Laminaria g ephemera (producing 10 spores at an age of 6 t o 8 weeks) than f o r L a m i n a r i a g s e t c h e l l i i ( p r o d u c i n g 10 spores a t 2 or more y e a r s of age). 2.  Developmental time  t o m a t u r i t y was  observed  semelparous than f o r the i t e r o p a r o u s sporophyte,  to  be  shorter  as p r e d i c t e d .  Conversely,  than 1 y e a r of age,  Laminaria and  setchellii  the  I n d i v i d u a l s of  L a m i n a r i a ephemera were e s t i m a t e d t o become r e p r o d u c t i v e at an age weeks.  for  of 6  to  8  d i d not become r e p r o d u c t i v e at l e s s  seldom b e f o r e the second  or even t h i r d y e a r .  Delayed  - 81 -  maturity  in  the i t e r o p a r o u s  a v a i l a b l e resources  sporophyte p o s s i b l y r e s u l t s from p a r t i t i o n i n g of  between the a l t e r n a t i v e processes  of r e p r o d u c t i o n  and of  s t i p e growth and maintenance.  3. (as  There i s no evidence  the  mean  ratio  of  i n these  sorus  data  surface  that area  annual  reproductive  to vegetative  s u r f a c e area) i s  g r e a t e r f o r the semelparous than f o r the i t e r o p a r o u s sporophyte. sorus  surface  area  to  from 13% t o 19% (Cable Laminaria  setchellii.  vegetative  Beach)  support  Bay:  14%  to  Between  setchellii:  species,  Between-species  are s m a l l e r 84%)  than  setchellii, indicate  differences  populations  are  intraspecific  single  prediction  populations  of  effort  species,  comparisons of r e p r o d u c t i v e  The  differences  and  mean  values  in  the  semelparous reproductive  increased  effort  s p e c i e s was not supported  obscure  which  may  high  Execution e f f o r t (L.  and  data  between  may  preclude  with  age  overall  of a g e - s p e c i f i c trends  by these  variability  this  data.  in  trends w i t h i n  the d i s c r e t e method of sampling used i n  identification  within  variability  reproductive  reproductive  effort,  reproductive  both  (L.  and t h e r e f o r e do not  E x e c u t i o n Bay: 8 4 % ) . These  such  observed  individuals.  Rock) and from  individual  in  i s variable  r e s u l t may be a t t r i b u t a b l e t o the  precluded  effort  Bay); i n  any  e f f o r t between s p e c i e s .  of the i t e r o p a r o u s  Alternatively,  ephemera v a r i e d  (L. ephemera. E x e c u t i o n Bay: 92%; L. s e t c h e l l i i ,  reproductive  of a  maximum  i n maximum  The r a t i o of  (Execution  30%) a r e n e a r l y i d e n t i c a l ,  Wizard Rock: 44%; L. s e t c h e l l i i .  that  32%  the  the e x p e c t a t i o n of i n c r e a s e d r e p r o d u c t i v e  species. effort  from  i n Laminaria  t h i s r a t i o v a r i e d from 1% t o 18% (Wizard  2% t o 32% ( E x e c u t i o n B a y ) . ephemera: 32%; L.  and  surface area  effort  This  individual  populations.  study  i n reproductive  among  may  have  e f f o r t among  - 82 For  a stable population i n  individual  must  replace  which  itself  rate  of  ( i . e . enhanced  invoked  i n order  rate  and  gametophyte  equals  death  during i t s l i f e t i m e .  ephemera are  replacement,  increase  birth  once  f e c u n d i t i e s e x h i b i t e d by L a m i n a r i a successful  -  sufficient  alternative  longevity  or  The to  as  ephemera, but m a i n t a i n s  s m a l l e r than t h a t of L. specific  differences  in  population processes. gametophyte l i f e  must  ephemera. the  T h i s suggests  contribution  Such d i f f e r e n c e s  The  problem of a l t e r a t i o n of  be  approached i n t u i t i v e l y .  i n a s i n g l e zygote-to-zygote associated  with  maintaining  only a s i n g l e  diplontic  each  a s s o c i a t e d r i s k may  increase  phase  may  in  be  Laminaria  same magnitude  existence  of  the  gametophyte to observed  be  effected  gametophyte Inherent  by  of  species-  alteration  life  history  of  reproductive the  be  events.  For  episode  relevant  per  significantly  those per  risk  the  enhanced  compensated f o r or exceeded by  the  magnitude  of the r i s k  complex l i f e  term i s simply  risk terms  histories  zygote-to-zygote  zygote-to-zygote  cycle  t h a t of  h i s t o r i e s with cycle,  the more  reproduction-  increased.  for complex-life-history populations size,  reproductive  Reproduction—associated  However, f o r complex l i f e  episode  characteristics  i n a l l non-vegetative  of the c y c l e .  episode.  reproductive  In order  not  the  c y c l e i n c r e a s e s as the product  organisms),  observed r e p r o d u c t i v e one  need  history characteristics.  of r i s k i s v a r i a b l e between r e p r o d u c t i v e  than  a  an annual sporophyte replacement r a t e much  events i s the r i s k of o f f s p r i n g m o r t a l i t y , or l a c k of success;  (i.e.  for  population  to account f o r the observed p o p u l a t i o n p r o c e s s e s .  however, e x h i b i t s an annual s p o r i c f e c u n d i t y of the  L.  allow  fecundity)  any  high sporic  mechanisms of  setchellii, as  rate,  risk  associated  an i n c r e a s e i n  to  remain with  fecundity.  stable  complexity For  or  to  must  be  complex  life  -  histories, the  individual  attractive the  overall  (zygote-to-zygote)  fecundities  to  83  of  fecundity  between-stage  history:  this  afford  of  Alternatively,  i f reproduction-associated  w i t h i n that value  is  mortality  would  compensation  fecundity  increases  greater  accruing  than  s i n g l e phase must  one  to  than one  the  events.  It  of is  f o r a l l stages i n  greatest  potential  for  reproduction-associated  risk.  r i s k a c c r u e s to more than one  phase,  i n only  increase  as the product  reproductive  p r e d i c t mean f e c u n d i t i e s of g r e a t e r  complex l i f e  but  -  a s i n g l e phase, then f e c u n d i t y  multiplicatively  over  a  comparable  f o r the non-complex c o n d i t i o n .  Data p r e s e n t e d above do not bear d i r e c t l y on the problem life  h i s t o r y c h a r a c t e r i s t i c s , and  gametophyte s u r v i v o r s h i p and history outset overall  characteristics of t h i s kelp  study, and life  fecundity  do  not  the  history  no  i n the f i e l d .  strictly  confirm of  implicated.  gametophyte c o n t r i b u t i o n t o p o p u l a t i o n  gametophyte  e s t i m a t e s are a v a i l a b l e f o r p r o c e s s e s of  importance is  of  Observed sporophyte  the p r e d i c t i o n s made at  gametophyte  dynamics  The  and  nature  to  life the the  magnitude of  p r o c e s s e s remains u n i d e n t i f i e d .  - 84 -  BIBLIOGRAPHY  Abbott, I.A., and G.J. H o l l e n b e r g . 1976. Marine Stanford U n i v e r s i t y Press, Stanford, C a l i f . 827 pp.  Algae  of  Anderson, E.K., and W.J. N o r t h . 1967. Zoospore r e l e a s e r a t e s i n Macrocvstis. B u l l . So. C a l . Acad. S c i . 66: 223-232.  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Princeton  University  a  - 90  -  APPENDIX 1  STIPE RING FORMATION IN LAMINARIA SETCHELLII  INTRODUCTION Visible by  various  determine invoked  c o n c e n t r i c r i n g s at the base of some k e l p s t i p e s have authors  minimum age  (Novaczek, of the  1981;  individual.  seasonal  p e r i o d s of f a s t  of annual  hapteron  is  1963:  hyperborea  Parke,  evidence  used  1948) has  to  been  K a i n (1963) and Novaczek (1971) and  in  Ecklonia  radiata  to  slow growth, coupled w i t h o b s e r v a t i o n of p e r i o d s  initiation.  not been r e p o r t e d i n the  results  and  1971,  Correlational  t o show t h a t these r i n g s are annual.  r e l a t e r i n g formation i n Laminaria  The  Kain,  been  Direct  o b s e r v a t i o n of s t i p e r i n g f o r m a t i o n has  literature.  r e s u l t s of a 12 month .in s i t u t a g g i n g study are g i v e n constitute direct  evidence  below.  that r i n g formation i n Laminaria  These  setchellii  annual.  MATERIALS AND  One tagged  hundred i n d i v i d u a l s of and  observation.  numbered  on  27  METHODS  Laminaria October  setchellii  1981  for  the  Tags were s e c u r e l y f a s t e n e d by n y l o n cable  the base of each s t i p e .  at  Wizard  purpose ties  Rock of  were  repeated  positioned  at  Subsequent o b s e r v a t i o n s showed t h a t most tags d i d not  remain i n p l a c e , but moved f r e e l y up and down the s t i p e w i t h water motion.  All 1982.  tagged  i n d i v i d u a l s were h a r v e s t e d from Wizard  Rock  on  19  November  P l a n t s were r e t u r n e d t o the l a b o r a t o r y , where l o n g i t u d i n a l - and c r o s s -  - 91 -  s e c t i o n s of some s t i p e s were made.  RESULTS AND  DISCUSSION  In only 17% of the s u r v i v i n g tagged p l a n t s d i d the cable place  at  localized cable  the  s t i p e base f o r an e n t i r e y e a r .  'saddles'  tie.  In  case,  the  in  These t e n p l a n t s had developed  from c o n s t r a i n t of l a t e r a l  every  t i e remain  growth i n  increase  corresponded, i n l o n g i t u d i n a l s e c t i o n , t o one  the  region  of  the  i n g i r t h of surrounding  tissues  cortical  (Figure  growth  ring  A.l).  The  observed g i r d l i n g phenomenon can be  explained  p a t t e r n s r e p o r t e d f o r p e r e n n i a l s p e c i e s of L a m i n a r i a . r e s u l t s from meristodermal c e l l secondary lateral  cortex  interior  expansion may  precludes  increase  allow in  to  divisions, the  and  cross-sectional  of area  Increase  subsequent  meristoderm.  the occurrence  according  cell  c o n s t r a i n t of  i n the months of March and A p r i l ;  stipe  The meristoderm  from  of  secondary  two  sites  (re:  t h i s corresponded t o a time  ' p e e l i n g ' , and t o i n i t i a t i o n of new r i n g s .  succeeded by a narrow, i n c i p i e n t  i s apparent, then,  annually,  but  i n s t i p e g i r t h i n the g i r d l e d r e g i o n .  s t i p e s made d u r i n g these months showed a d i s t i n c t ,  It  a  and Methods, Chapter 4) i n d i c a t e d t h a t meristodermal d i v i s i o n r a t e s  are g r e a t e s t observable  of  divisions,  of the s t i p e .  Seasonal h a r v e s t i n g and s e c t i o n i n g of k e l p s t i p e s Materials  girth  production  would t h e r e f o r e remain i n t a c t , but would undergo no development c o r t e x and no i n c r e a s e  growth  i n stipe  Artificial  limited  to  that Laminaria  setchellii  and t h a t new r i n g s are i n i t i a t e d  C r o s s - s e c t i o n s of  dense outer  l a y e r of l o o s e l y - a r r a n g e d  tissue  secondary  s t i p e r i n g s are  synchronously  of  layer,  cortex.  produced  within a population.  - 92 -  G e n e r a l l y , r i n g widths  become s u c c e s s i v e l y narrower  w i t h i n c r e a s i n g s t i p e diameter;  accuracy  w i t h i n c r e a s i n g number of r i n g s . minimum  age,  i n years,  interpreted accordingly.  in  with  increasing  of o b s e r v a t i o n consequently  age  or  decreases  V i s i b l e r i n g s are t h e r e f o r e an i n d i c a t i o n of  discrete  time,  and  resulting  data should be  -  93  -  A t r a n s i t i o n zone  1mm  F i g u r e A . l . L o n g i t u d i n a l c r o s s - s e c t i o n of s t i p e base, s h o w i n g g i r d l e d r e g i o n and i n c r e a s e i n g i r t h o f a d j a c e n t tissues. (Drawn f r o m a p h o t o g r a p h ) .  - 94 -  APPENDIX 2  GAMETOPHYTE CULTURE OF LAMINARIA  EPHEMERA AND L. SETCHELLII  MATERIALS AND METHODS  More than 60 r e p l i c a t e gametophyte c u l t u r e s each and  Laminaria  1981. and  s e t c h e l l i i were e s t a b l i s h e d d u r i n g  immediately  returned  to  the  fronds  were s u r f a c e - s t e r i l i z e d  and p a r t i a l l y at  dessicated.  Laminaria  ephemera  the p e r i o d May through J u l y ,  A l l c u l t u r e s were i n i t i a t e d as f o l l o w s : f e r t i l e  fronds  were  collected  l a b o r a t o r y , where they were m a i n t a i n e d i n  f l o w i n g sea water f o r a maximum of 24 hours b e f o r e  water  of  (0.1% B e t a d i n e  use.  Fronds or p o r t i o n s of  solution i n sterile  S o r a l t i s s u e s were then reimmersed i n  sea w a t e r ) , sterile  sea  10°C; a f t e r zoospore r e l e a s e , 1 ml of spore s u s p e n s i o n was p i p e t t e d  i n t o each 60 X 15 mm  p e t r i d i s h already  c o n t a i n i n g 15 mis P r o v a s o l i ' s  enriched  sea  A l l dishes  sealed with Parafilm to avoid  salinity  water  (PES).  i n c r e a s e by e v a p o r a t i o n . incubators  at  5,  10,  were  Dishes were stacked and  15°C,  under  5 deep and  long-day  placed  (16L:8D)  i n Percival c o n d i t i o n s , at  2 irradiance replaced  of about 100jUE/cm / s e c , c o o l white f l u o r e s c e n t l i g h t . at  approximate bi-weekly i n t e r v a l s .  c u l t u r e s at a concentration  cultures.  culture  of  each  species.  and E x e c u t i o n Bay; L a m i n a r i a represented.  initiation  was  used  No two fronds were from the same parent  p r o d u c t s of 12 or more p a r e n t a l cultures  Germanium d i o x i d e was added t o  of 5 mg/l (Lewin, 1966).  Each f r o n d s e l e c t e d f o r replicate  Medium was  to  establish  sporophyte.  genotypes were t h e r e f o r e r e p r e s e n t e d  A l l study s i t e s  (Laminaria  species.  The  among the  ephemera: Cable Beach  s e t c h e l l i i : W i z a r d Rock and E x e c u t i o n  R e s u l t s were pooled w i t h i n  5  Bay)  were  - 95 -  O b s e r v a t i o n s are p r e s e n t e d i n T a b l e A . l . statistical  inferences  are  made.  For  Results are q u a l i t a t i v e ,  each  combination  c h a r a c t e r , and time, a '+' i s r e c o r d e d i f t h a t c h a r a c t e r least  some  cultures;  a  '-'  indicates  that  no  of  was  treatment,  present  cultures  and no  i n at  exhibited  that  character.  RESULTS  L a m i n a r i a ephemera germinated and grew v e g e t a t i v e l y Gametophytes to  were  strictly  development  was  but  sporophytes. Some or  were  than  to  males  of  other  species.  observed only a f t e r the n i n t h week a t 10 and 15°C.  No s e x u a l i t y was observed a t 5°C. cultures,  and 15°C.  isomorphic, and t h e i r morphology was more s i m i l a r  females of other s p e c i e s of L a m i n a r i a  Oogonium  at 5, 10,  presumed  A n t h e r i d i a were never  to  be  present  There was sparse development of  in  i d e n t i f i e d among  cultures  sporophytes  which  at  10  the  produced and 15°C.  sporophytes were i s o l a t e d from the d i s h e s and removed t o bubble  culture,  t o greenhouse c u l t u r e , where they a t t a i n e d o v e r a l l l e n g t h s of 15 t o 25  Gentle  grinding  of  cm.  v e g e t a t i v e l y - g r o w i n g gametophytes a f t e r the second month  o f t e n i n i t i a t e d p r o d u c t i o n of oogonia.  Laminaria s e t c h e l l i i Gametophytes  germinated  were heteromorphic.  and grew v e g e t a t i v e l y a t 5, 10, and 15°C.  At 10 and 15°C, oogonia and a n t h e r i d i a were  observed among some c u l t u r e s by the end of the second cultures  by  the  fourth  week.  week,  Ten and  15°C  treatments  were  weeks.  at  were  maintained  for 4  held  v e g e t a t i v e l y , but produced  5°C  among  most  Dense p r o d u c t i o n of sporophytes was observed  w i t h i n sexual c u l t u r e s . Cultures  and  n e i t h e r oogonia nor a n t h e r i d i a .  terminated  after  4  months; these grew  LAMINARIA T°C  WEEKS  1-2  05°C  GERMINATION  +  5-8  LAMINARIA S E T C H E L L I I  +  3-4  EPHEMERA 9-12  13-16  VEGETATIVE GROWTH  1-2  3-4  5-8  9-12  +  +  +  +  +  i ii  i i  I  I  I  I  I  I  SPOROPHYTES  I  I  I  GERMINATION  +  VEGETATIVE GROWTH  +  OOGONIA ANTHERIDIA  13-16  i  10°C  + +  +  OOGONIA  +  +  +  +  TERMINATED  +  +  +  +  TERMINATED  +  +  TERMINATED  +  TERMINATED  ANTHERIDIA  15°C  SPOROPHYTES  -  -  -  +  +  GERMINATION  +  VEGETATIVE GROWTH  +  +  +  +  +  +  +  TERMINATED  OOGONIA  -  -  -  +  +  +  +  TERMINATED  +  +  TERMINATED  +  +  TERMINATED  +  ANTHERIDIA SPOROPHYTES  Table A . l .  Results  -  -  -  o f gametophyte c u l t u r e  +  +  experiments.  See t e x t  f o r explanation  o f symbols.  

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