Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Factors affecting swimbladder volume in rainbow trout (Salmo gairdneri) held in gas suppersaturated water Shrimpton, James Mark 1987

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1988_A6_7 S47.pdf [ 3.03MB ]
Metadata
JSON: 831-1.0097852.json
JSON-LD: 831-1.0097852-ld.json
RDF/XML (Pretty): 831-1.0097852-rdf.xml
RDF/JSON: 831-1.0097852-rdf.json
Turtle: 831-1.0097852-turtle.txt
N-Triples: 831-1.0097852-rdf-ntriples.txt
Original Record: 831-1.0097852-source.json
Full Text
831-1.0097852-fulltext.txt
Citation
831-1.0097852.ris

Full Text

FACTORS AFFECTING SWIMBLADDER VOLUME IN RAINBOW TROUT CSALMO  GAIRDNERI)  HELD IN GAS SUPERSATURATED WATER By JAMES MARK SHRIMPTON B.Sc.CHonours), U n i v e r s i t y o f V i c t o r i a , 198S  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES CDepartment o f Zoology)  We accept t h i s t h e s i s as conforming to the required  standard  THE UNIVERSITY OF BRITISH COLUMBIA December 1987 ® J . MARK  SHRIMPTON, 1987  In  presenting  degree freely  at  this  the  available  copying  of  department publication  of  in  partial  fulfilment  University  of  British  Columbia,  for  this or  thesis  reference  thesis by  this  for  his thesis  and  scholarly  or for  her  Department  V6T D a t e  DF-fin/ft-n  Columbia  1Y3  DfctL.  5  \Ofifl  I further  purposes  gain  the  requirements  I agree  shall  that  agree  may  representatives.  financial  permission.  The University of British 1956 Main Mall Vancouver, Canada  study.  of  be  It not  is  that  the  Library  permission  granted  by  understood be  for  allowed  an  advanced  shall for  the that  without  make  it  extensive  head  of  my  copying  or  my  written  ii ABSTRACT  I examined t h e response o f gairdneriJ  s w i m b l a d d e r bo  positioned i n pressure  the  swimbladder pressure.  fish  facilitating  swimbladder  pressure  of  trout.  water.  were  direct  the  of  pressure. total  the  gas  water.  The  C P O 2  =  IdO mmHg).  Swimbladder  response and  minimum  was f o r c e d o u t t h e p n e u m a t i c d u c t . pressure  i s s i z e dependent,  with  e x p e l swimbladder gas i n s m a l l e r s w i m b l a d d e r due density.  to  The b u o y a n t  increased force  g r e a t e s t f o r f i s h below lOg. for  swimbladder  overinflation.  pressure The  the  fish.  The  pressure created  by  of of  increased u n t i l  pressure  causes  a  decreased  a  gas 27 gas  release  required  expansion  of  oxygen  AP  duct  a  showed  showed  level  pneumatic  greater  to  water  s u p e r s a t u r a t i o n o b s e r v e d t o c a u s e t h i s r e s p o n s e was a mmHg  Cannulas  measurement  pressure The  CSalmo  connected  Fish held i n supersaturated  s t r o n g d e p e n d e n c e on partial  rainbow  supersaturated  swimbladder  transducer,  an i n c r e a s e i n  gas  the  of  to the  decrease  in  density  is  These f i s h seek depth t o compensate  iii TABLE OF  CONTENTS PAGE  Abstract  i  L i s t o f Tables  i iv  L i s t of Figures  v  Acknowledgements  v i i  1.0  Introduction  1  2.0  Methods and M a t e r i a l s  11  2.1  P r o d u c t i o n o f S u p e r s a t u r a t i o n and Water A n a l y s i s  11  2.2  Determination o f Swimbladder I n f l a t i o n Threshold  13  2.3  D e t e r m i n a t i o n o f Pneumatic Duct Release P r e s s u r e  15  2.3.1  D i r e c t Measurement Pressure  16  2.3.2  I n d i r e c t Measurement Pressure  2.4  Swimbladder Expansion  19  2.5  Behavioural Experiments  21  3.0  Results  24  3.1  R e s p o n s e o f S w i m l b a d d e r t o Gas S u p e r s a t u r a t e d W a t e r  24  3.2  Pneumatic Duct Release P r e s s u r e  35  3.3  Swimbladder Expansion  39  3.4  B e h a v i o u r a l Response  44  4.0  Discussion  48  5.0  Summary  59  6.0  Literature Cited  60  o f Pneumatic Duct Release o f Pneumatic Duct Release  16  iv L I S T OF TABLES TABLE 1  PAGE S t a t i s t i c s f o r r e g r e s s i o n o f r a t e o f swimbladder i n f l a t i o n on d i s s o l v e d g a s t e n s i o n f o r f i v e l e v e l s of P 0 o  33  V L I S T OF FIGURES FIGURE  PAGE  1  D i a g r a m o f a p p a r a t u s u s e d i n t h e measurement o f swimbladder p r e s s u r e f o r f i s h h e l d i n a i r supersaturated water  14  2  A p p a r a t u s used t o measure t h e p r e s s u r e w i t h i n the swimbladder r e q u i r e d t o f o r c e gas out t h e pneumatic duct f o r f i s h l e s s than 50g  17  3  Diagram o f t h e o b s e r v a t i o n column used t o monitor the depth d i s t r i b u t i o n o f the f i s h f o r d i f f e r e n t l e v e l s o f TGP  22  4  I n c r e a s e i n s w i m b l a d d e r p r e s s u r e f o r a 195g f i s h h e l d i n gas s u p e r s a t u r a t e d water CAP = 50 mmHg)  25  5  V e n t i n g o f g a s o u t t h e p n e u m a t i c d u c t when a i r was i n f u s e d i n t o t h e s w i m b l a d d e r  26  6  I n c r e a s e i n s w i m b l a d d e r p r e s s u r e f o r a 184g f i s h h e l d i n gas s u p e r s a t u r a t e d water CAP = 29 mmHg)  28  7  R e l e a s e o f gas out t h e pneumatic d u c t d u r i n g i n f u s i o n o f a i r i n t o the swimbladder  29  8  Rate o f i n c r e a s e i n swimbladder p r e s s u r e f o r f i s h h e l d i n d i f f e r e n t l e v e l s o f gas s u p e r s a t u r a t e d water  31  9  P l o t o f TGP t h r e s h o l d C F i d l e r , 1 9 8 5 ) a n d s w i m bladder i n f l a t i o n data as a function o f P O 2  36  10  Pneumatic duct r e l e a s e p r e s s u r e a s a f u n c t i o n of f i s h weight  37  11  Pneumatic duct r e l e a s e p r e s s u r e a s a f u n c t i o n of f i s h weight p l o t t e d l o g a r i t h m i c a l l y  38  12  R e l a t i o n s h i p between t h e p r e s s u r e and volume o f t h e s w i m b l a d d e r f o r a 9.5g r a i n b o w t r o u t  41  D e n s i t y o f r a i n b o w t r o u t a t DRP of f i s h weight L i f t f a c t o r c a l c u l a t e d a t DRP of f i s h weight  as a  as a  function  function  Depth d i s t r i b u t i o n f o r rainbow t r o u t as a f u n c t i o n o f TGP a n d f i s h w e i g h t  ACKNOWLEDGEMENTS  I am g r a t e f u l  to several  individuals,  who  generously  gave o f t h e i r time and e x p e r t i s e toward t h e completion thesis. and  In p a r t i c u l a r ,  helpful  I thank Dr.  Dave R a n d a l l f o r h i s  c r i t i c i s m of t h i s project.  I extend my  t o Mr. L a r r y F i d l e r , f o r h i s guidance and the  study.  Station,  I thank Mr. Jon Jensen,  Nanaimo,  B.C.,  f o r advice  of  Dr.  this  support  appreciation  assistance  throughout  the P a c i f i c  Biological  and  tensionometer and t h e o b s e r v a t i o n column. by  of  f o r t h e loan Review o f  Malcolm Shrimpton i s g r a t e f u l l y acknowledged.  thank my w i f e J u l i e , f o r her h e l p and encouragement.  the  of a thesis  Finally,  I  1 1.0  INTRODUCTION  F i s h exposed t o water s u p e r s a t u r a t e d w i t h  atmospheric  g a s e s c a n d e v e l o p a p h y s i c a l l y i n d u c e d s y n d r o m e c a l l e d Gas B u b b l e Trauma CGBT), where g a s b u b b l e s tissues of the fish was f i r s t lethal  aquatic  d i s s o l v e d gas  in  the  blood  CPauley and N a k a t a n i , 1967).  r e c o g n i z e d by M a r s h  to  form  and  animals.  Gorham  After  supersaturation  was  to  other  condition  and  initial  considered  p r o b l e m , c o n f i n e d t o man made f i s h r e a r i n g  The  C1905),  this  and  can  be  research, be  a  facilities.  minor It  o f t e n c a u s e d by f a u l t y pumps a n d a i r e n t r a i n m e n t i n w a t e r  was  intake  pipes. A measure o f t h e degree o f s u p e r s a t u r a t i o n o f t h e is  t h e t o t a l d i s s o l v e d g a s p r e s s u r e CTGP), a n d i s e x p r e s s e d a s  percent of saturation. at  water  100%  TGP.  At  a  The w a t e r i s i n e q u i l i b r i u m w i t h t h e a i r  levels  s u p e r s a t u r a t e d w i t h gases.  of The  TGP  above  degree  of  100%  the  water  supersaturation  a l s o b e e x p r e s s e d a s t h e e x c e s s d i s s o l v e d g a s p r e s s u r e , AP.  i s can The  two e x p r e s s i o n s a r e r e l a t e d by t h e e q u a t i o n : AP + BP TGP %  =  * 100  1.1  BP With t h e advent o f l a r g e s c a l e the  hydro—electric  dams  Columbia and Snake R i v e r systems i n t h e 1960s, a s e r i o u s  supersaturation  problem  developed  p r e s s u r e CTGP) v a l u e s o n t h e  CEbel,  Columbia  excess o f 130% o f s a t u r a t i o n CClark,  River 1977).  1969). were  Total recorded  Massive  kills  on gas gas in of  2 m i g r a t i n g s a l m o n i d s a l e r t e d s c i e n t i s t s once a g a i n t o t h e problem. A  relationship  was  established  between  fish  r e s e r v o i r s p i l l a g e o v e r h y d r o e l e c t r i c dams.  During  when w a t e r p a s s e d t h r o u g h t h e power g e n e r a t i n g not  exposed  to  the  aerating  s u p e r s a t u r a t i o n l e v e l s were low.  effect During  mortality flow  turbines  of  the  and  periods and  was  spillways,  the spring flood period,  l e v e l s o f g a s s u p e r s a t u r a t i o n were h i g h e s t .  At  this  time  flow  was r e l e a s e d o v e r s p i l l w a y s a n d a i r was e n t r a i n e d i n t h e w a t e r a s i t p a s s e d o v e r t h e dam.  The i n c r e a s e d  presssure  p l u n g e d i n t o t h e b a s i n b e l o w t h e dam f o r c e d and  supersaturated  the  water.  r e s u l t e d i n abnormally  the  a i r into  These  high  c o r r e s p o n d e d t o t h e downstream m i g r a t i o n o f and  as  water  solution,  flow  periods  juvenile  salmonids,  h i g h m o r t a l i t i e s CBeiningen and  Ebel,  1970). Water q u a l i t y c r i t e r i a formulated  i n t h e USA.  supersaturation  levels  Since f i s h of  110%  f o r gas  w e r e f o u n d t o be TGP  or  c o m m i t t e e C1973) o n w a t e r q u a l i t y c r i t e r i a t h e maximum a c c e p t a b l e  supersaturation  l i m i t f o r TGP.  affected  greater,  the  established  However,  were  the  at  USEPA  110?; a s biological  d a t a u p o n w h i c h t h e USEPA c r i t e r i a w e r e b a s e d w e r e t y p i c a l o f t h e Columbia R i v e r system and i t s h i g h l e v e l s o f water.  The c r i t e r i a d i d n o t a c c o u n t f o r l o w l e v e l s  the e f f e c t s o f long term exposure. n o t be a p p l i c a b l e t o t h e s e fish  gas  Therefore,  s i t u a t i o n s C C o l t , 1983).  hatcheries are inherently susceptable  CBouck, 1 9 8 0 ) .  the  supersaturated of  TGP  and  criteria  may  F o r example,  t o low l e v e l s  of  TGP  Stream m o d i f i c a t i o n s f o r j u v e n i l e r e a r i n g and t h e  use o f ground water o f t e n r e s u l t i n s l i g h t l y gas p r e s s u r e s .  .elevated  Rearing channels a r e subject  to  solar  which d e c r e a s e s t h e gas s o l u b i l i t y o f t h e water. supplies areoften supersaturated i n nitrogen  dissolved heating  Ground  gas  due  water t o the  d e n i t r i f i c a t i o n o f n i t r a t e CSigma, 1983). Studies  of  some  salmonid  hatcheries  have  shown  m o r t a l i t i e s t o o c c u r a t l e v e l s w e l l b e l o w 1 1 0 % TGP.  Wright  and  McLean  level  gas  s u p e r s a t u r a t i o n on Chinook f r y i n a 122 d a y r e a r i n g p e r i o d .  They  C1985)  examined  the  effects  of  low  a t t r i b u t e d a 2 . 5 % m o r t a l i t y t o TGP l e v e l s a v e r a g i n g 1 0 5 % . was a l s o a f f e c t e d b y TGP.  The a v e r a g e w e i g h t  of  a e r a t e d w a t e r CTGP = 1 0 0 % ) was s l i g h t l y more t h a n  fish  held  in  fish  held  i n  s u p e r s a t u r a t e d w a t e r , b u t t h i s was n o t s t a t i s t i c a l l y  significant.  However, t h e c o n d i t i o n c o e f f i c i e n t s w e r e s i g n i f i c a n t l y i n d i c a t i n g t h a t f i s h from a e r a t e d t r o u g h s were to t h e i r length than c o n t r o l f i s h Dawley  and  Ebel  C1975)  reported  swimming  f i s h h e l d i n 1 0 6 % TGP was  not attributed  that  Bouck  to  TGP  gairdneri')  trout  CSal  mo  truita)  greater and  than  since  C1980)  a t t o t a l g a s p r e s s u r e s l e s s t h a n 108%.  of  gross  found  that  Hatchery f i s h i n  70%  f o r rainbow  of  reduced  Mortality  M i c h i g a n were a l s o d i s c o v e r e d t o be s e n s i t i v e t o  brown  days  performance.  not evident.  W e s t e r s C1983) r e p o r t e d  exposure  35  h a t c h e r y t r o u t d i e d f r o m GBT i n 1 0 5 % TGP w a t e r .  TGP.  relative  ( W r i g h t a n d McLean, 1 9 8 5 ) .  growth r a t e s and i m p a i r e d  were  different,  heavier  j u v e n i l e C h i n o o k a n d s t e e l h e a d t o 1 0 6 % TGP f o r  symptoms o f GBT  Growth  low  levels  of  mortality f o r trout  CSalmo  The l i t e r a t u r e  4 clearly  i n d i c a t e s t h a t m o r t a l i t y f r o m GBT  USEPA c r i t e r i u m o f  110%.  At  these  can  lower  occur  below  levels  of  TGP  e v i d e n c e o f v a s c u l a r system b u b b l e s have been r e p o r t e d . o t h e r symptoms o f GBT a r e e v i d e n t .  intestinal  no  However,  The symptoms o f t e n  form o f overexpansion o f t h e swimbladder,  the  take  the  tract  and  that  will  accumulation o f gases i n t h e b u c c a l c a v i t y . Determination of a threshold l e v e l i n d u c e GBT i s v i t a l l y  of  TGP  important f o r the protection  of  s a l m o n i d s t o c k s and r e a r i n g o f j u v e n i l e s a l m o n i d s i n D e t e c t i o n o f t h e l o w e s t l e v e l o f TGP t h a t w i l l b u b b l e s c o u l d i n d i c a t e s a f e l e v e l s o f TGP.  hatcheries.  induce  growth  of  a  threshold  f o r e m b o l i g r o w t h , F i d l e r C1984) e x a m i n e d t h e p h y s i c a l  parameters  affecting the  formation  swimbladder and t h e  of  ambient  m o r t a l i t i e s can occur a t  TGP  bubbles  in  water.  His  levels  To f i n d  migrating  the work  below  bubble f o r m a t i o n i n t h e v a s c u l a r system.  vascular  indicates  the  Chronic mortality i s probably a  bubble growth.  The h o l l o w o r g a n s C i e .  buccal  and  cavity  swimbladder)  and  are  TGP  result  divided  levels  of  into to  exceed  extravascular  gastro-intestinal areas  for  Jensen  Acute m o r t a l i t y i s l i k e l y  r e s u l t f r o m i n t r a v a s c u l a r b u b b l e g r o w t h when 110%.  that  threshold  Alderdice  C1985) h a v e a l s o s u g g e s t e d m o r t a l i t y r e s p o n s e s a r e two c a t e g o r i e s , a c u t e a n d c h r o n i c .  system,  that  tract,  show  an  a c c u m u l a t i o n o f g a s e s when f i s h a r e e x p o s e d t o g a s s u p e r s a t u r a t e d water.  J e n s e n C1980) a s s o c i a t e d m o r t a l i t y i n  with bubbles i n the buccal cavity.  Cornachia  observed bubbles i n the d i g e s t i v e t r a c t o f  steelhead and  larval  alevins  Colt striped  C1984) bass  5 (Morone  saxatilis'),  Hyperinflation CShirata, Pacific  t h a t p r o d u c e d damage t o t h e e p i t h e l i a l of  1966;  the  Cornachia  Biological  communication).  and  Colt,  Station,  This  study  has  also  been  1984;  Nanaimo,  focuses  J.O.T. B.C.,  personal the  the  of  the  The d o w n l o a d i n g o f b l o o d g a s e s i n t o t h e s w i m b l a d d e r  i s  f i s h t o the excess  and  response  buoyancy.  on t h e d e g r e e o f v a s c u l a r i z a t i o n o f  the  P h y s o c l i s t s have w e l l v a s c u l a r i z e d swimbladders, s e c r e t i o n and gas r e a b s o r p t i o n s u r f a c e s . downloading o f oxygen  water h a s been  concluded  a t depth.  to  cause  Gas  buoyancy  undulatus)  Physostomes  possess  a  swimbladder t o t h e esophagus,  short  of  i n the  CChamberlain  gulping  a i r at  duct  are  the  that  CFange,  CJasinski,  probably s u f f i c i e n t t o  allow  1963).  These  the  passage  of  CSteen, the  duct.  Gas  pneumatic  1976).  blood  to  connects  i s forced i n v i athe surface  able  reabsorption  s w i m b l a d d e r w a l l i s v a s c u l a r i z e d p r i m a r i l y by a r t e r i e s artery  physostomes  not  known a s t h e p n e u m a t i c  needed t o i n f l a t e t h e swimbladder  coeliac  a  1980).  a d j u s t b l a d d e r v o l u m e by g a s s e c r e t i o n a n d  by  as  supersaturation  and l a c k s p e c i a l i z e d g a s t r a n s f e r o r g a n s , a n d  duct  gas allow  bladder  Unlike the A t l a n t i c Croaker, salmonids are  1970).  wall.  possessing  the  positive  p h y s o c l i s t A t l a n t i c C r o a k e r CMicropogon  cavity  These s t r u c t u r e s  from a r t e r i a l b l o o d t o  means o f m a i n t a i n i n g b u o y a n c y  e t al.,  Jensen,  of  i t s e f f e c t s on t h e f i s h ,  on  observed  overinflation  swimbladder,  dependent  swimbladder  cells.  from  vessels  gases  from  The the are the  6 a r t e r i a l s y s t e m a c r o s s t h e s w i m b l a d d e r w a l l , w h i c h may S t r o u d e t al.  swimbladder t o h y p e r i n f l a t e .  cause  the  C1975) r e p o r t e d  that  j u v e n i l e salmonids u s u a l l y e x h i b i t e d distended swimbladders  after  exposure t o excess  TGP.  The s w i m b l a d d e r i s an o r g a n t h a t c a n be c o n s i d e r e d t o be a very l a r g e bubble. contrast  to  the  As s u c h  vascular  the  radius  system,  the  is  very  pressure  overcome t h e s u r f a c e t e n s i o n f o r c e s t h a t r e s t r i c t i s low.  Consequently, i f  equilibrium with the inflation pressure. P0  2  should  arterial  ambient  occur  blood  water  whenever  the  gas TGP  However, t h e r a t i o o f P(>2 i n t h e  of  In  required  to  bubble  the  Consequently, the t o t a l  are  exceeds  atmospheric  arterial  d i s s o l v e d gas p r e s s u r e i s  swimbladder.  Fidler  for  downloading  C1985) t o o k t h e s e  of  system  tissues.  lower  gas  in  into  the  greater  into  that w i l l  F o r a f i s h h e l d i n gas  to  diffusion  levels  parameters  a n d d e r i v e d a r e l a t i o n s h i p f o r t h e t h r e s h o l d TGP swimbladder o v e r i n f l a t i o n .  in  swimbladder  and c o n s u m p t i o n o f oxygen a t t h e  required  is  tensions,  a r t e r i a l s y s t e m t h a n i n t h e a m b i e n t w a t e r a n d TGP 100%  growth  fish  i n t h e w a t e r CF r a t i o ) i s l e s s t h a n one due t o t h e  resistance at the g i l l  than  large.  the  account cause  supersaturated  water, the t h r e s h o l d e q u a t i o n i s : TGP where: B  C  S B  -  B  1.2  7  TGP_  =  BP + AP  P(>2  =  p a r t i a l p r e s s u r e o f oxygen  BP  =  barometric pressure  F  =  r a t i o o f a r t e r i a l PC>2 t o w a t e r PC>2  p  =  t h e d e n s i t y o f water  h  =  K  =  SB  i n t h e water  t h e depth o f water H  N  H H D D  °  N  N  Q  N  Q  / = = = =  /H  o o Henrys constant f o r nitrogen H e n r y s c o n s t a n t f o r oxygen Diffusivity of nitrogen D i f f u s i v i t y o f oxygen D  For d e r i v a t i o n o f t h i s equation s e e F i d l e r  C1985).  F i d l e r C1984) s u g g e s t e d t h a t m o r t a l i t y l e s s t h a n 1 1 0 % must hollow organs.  be  associated  with  at  TGP  overinflation  D i r e c t m o r t a l i t y h a s been o b s e r v e d  levels of the  from  rupture  of swimbladders i n rainbow t r o u t h e l d i n gas s u p e r s a t u r a t e d water C S h i r a t a , 1966).  This  result  implies  v e n t i n g o f gas o u t t h e pneumatic b u r s t t h e swimbladder  that  the pressure f o r  d u c t was g r e a t e r  membrane.  Therefore,  r e l e a s e o f gas through t h e pneumatic  than  the  pneumatic  p r e s s u r e CDRP) o n p h y s o s t o m e s  C1963).  28  c o n v o l u t e d and v a r i e s  physostome i n diameter  damage  pneumatic along  duct He  determined  the  duct  One release  pressure  b u t i t may d i f f e r f o r d i f f e r e n t s p e c i e s The  to  A  membrane,  fish.  adequate  mmHg.  does  of  seem  be  magnitude  sizes  not  to  was H a r v e y  to  pressure f o r  d u c t must b e e x a m i n e d .  o f t h e few r e s e a r c h e r s t o d e t e r m i n e t h e  DRP f o r s o c k e y e s m o l t s  that  of  this  swimbladder  and  different  i s  i t s length.  highly Fidler  C1984) s u g g e s t e d t h a t t h e r e l e a s e p r e s s u r e i s a s s o c i a t e d w i t h t h e  8 minimum r a d i u s o f t h e p n e u m a t i c  d u c t and s u r f a c e t e n s i o n  forces.  The r e l e a s e p r e s s u r e  related  of  pneumatic  will  be  d u c t a n d c a n be d e s c r i b e d  to  -  Po  radius  by t h e L a p l a c e  the  Equation.  a  2  Pi  the  =  1.3 r  Where  From e q u a t i o n radius.  1.3,  Pi.  i s the bubble i n t e r n a l  Po  i s the external  a  i s the surface  r  i s the bubble  t h e DRP  will  The minimum p r e s s u r e  fish,  to  diffusing increase Increases the  density  of  the  in  fish  will  the  fish,  the  size  pressure  also  expansion will  making  of  in  the  the  fish.  from  result  the  of  be l a r g e r f o r s m a l l  will  to  tension  t h e d u c t i s d e t e r m i n e d by  swimbladder  due  surface  duct  gases  a  volume  swimbladder.  r e s u l t i n a decrease  i t  positively  in  buoyant.  e v a l u a t i o n of the pressure/volume r e l a t i o n s h i p f o r the  swimbladder the  the  radius  overcome  i n t h e volume o f t h e f i s h  Therefore,  DRP,  increase  i n t o the swimbladder in  tension  I f the radius i s r e l a t e d t o  the duct release pressure An  pressure  be i n v e r s e l y r e l a t e d t o t h e  f o r c e s a n d a l l o w g a s t o move a l o n g smallest radius.  pressure  i s important. buoyant  o v e r i n f l a t i o n may F i s h may swimbladder.  The  lift  If a size relationship exists for exerted  on  the  fish  by  the  swimbladder  a l s o be s i z e r e l a t e d . seek depth t o compensate f o r increased  hydrostatic  pressure  t h e s w i m b l a d d e r and a l l e v i a t e p o s i t i v e buoyancy.  an  overinflated will  compress  However,  depth  c o m p e n s a t i o n h a s n o t b e e n shown c o n c l u s i v e l y CWeitkamp a n d  Katz,  9 1980).  Shrimpton  COncorhynchus  C1985)  kisutch^  i n c r e a s i n g TGP.  showed  that  distributed  juvenile  themselves  However, f i s h l e s s than  depth compensation response may t h i s response t o  determine  what  to  8g  impact  for  and  depth r e q u i r e d f o r f i s h t o a l l e v i a t e GBT.  In  a  I examined  of  gas  do  with  used,  overinflation  water o r not, most f i s h c u l t u r e f a c i l i t i e s  f i s h may  were  distribution  compensate  salmon  deeper  be dependent on s i z e .  swimbladder would have on the depth Whether f i s h seek depth  coho  of  the  salmonids.  supersaturated  not  provide  such  a  the  situation  have t o swim c o n t i n u o u s l y t o overcome t h e l i f t caused by  swimbladder  overinflation.  c o n t i n u o u s l y , they may  be  If  fish  carried  are  to  unable  the  surface  to  swim  where  they  indicate  that  become more s u s c e p t a b l e t o p r e d a t i o n . Many  observations  in  the  literature  swimbladder o v e r i n f l a t i o n i s a symptom o f GBT, problem  for  young  salmonids.  measurements  to  define  the  e l e v a t e d TGP,  I have s e t out  changes a s s o c i a t e d w i t h t h e  Since  there  response to  and i s  of  the  demonstrate  swimbladder  have  serious  been  swimbladder  the  due  a  to  few to  physiological dissolved  gas  s u p e r s a t u r a t i o n o f water. Using  Rainbow  trout  CSalmo  experimental animals i n t h i s study, were determined on a range o f f i s h  a  gairdneri}  number  sizes.  as  the  of  relationships  These  relationships  included: 1.  The  threshold  inflation;  TGP  that  will  cause  swimbladder  2.  3.  The  swimbladder  internal  pressure  that  v e n t i n g o f gas v i a the pneumatic duct  CDRP)j  The change i n f i s h d e n s i t y r e s u l t i n g  from  will  cause  swimbladder  overinflation; 4.  A l t e r a t i o n s i n behaviour t h a t suggest  water  depth  used by the f i s h t o compensate f o r changes i n body density.  is  11 2.0  2.1  METHODS AND MATERIALS  PRODUCTION OF SUPERSATURATION AND WATER ANALYSIS The  water  a e r a t o r systems.  TGP  was  One, designed  c o n s t r u c t e d out o f f o u r i n c h  controlled  precisely  t o supersaturate  PVC  pipe,  p l a s t i c i n t e r l o c s a d d l e s and s e a l e d  using  two  t h e water,  was  filled  at  both  with  ends.  3/4  inch  Water  and  compressed a i r Cor oxygen) were i n t r o d u c e d i n t o t h e t o p o f t h e column and allowed  t o pass through t h e s u b s t r a t e under  Adjustment o f a i r and water flow r a t e s determined gas pressure.  Pressure  the dissolved  f l u c t u a t i o n s i n t h e water  c o n t r o l l e d by an i n l i n e water flow r e g u l a t o r which constant water p r e s s u r e pressure  therefore,  a  system  were  maintained  constant  a  total  gas  Columbia  is  CTGP). Water  naturally  and  pressure.  at  the U n i v e r s i t y  supersaturated  of  British  Capproximately  104%).  i n t e r e s t e d i n t h e response o f t h e swimbladder  at  p r e s s u r e s near e q u i l i b r i u m , gas had t o be removed by a e r a t i n g t h e water  at  a  pressure  s t r i p p i n g column was c o n s t r u c t e d  below  out o f  four  As  I  dissolved from  gas  solution  atmospheric. inch  was  ABS  The pipe,  f i l l e d with 3/4 i n c h Koch f l e x i r i n g s , s e a l e d a t t h e top, with t h e bottom o f t h e p i p e r e s t i n g i n a 15 L p a i l .  Water was  introduced  i n t o t h e t o p and passed through t h e column under a s l i g h t vacuum. The  vacuum was c r e a t e d by a water a s p i r a t o r connected t o t h e t o p  o f t h e column. Outflows from both a e r a t o r s r a n i n t o a mixing  chamber.  12 D e s i r e d TGP l e v e l s c o u l d be achieved by a d j u s t i n g mixture Vater from t h e mixing chamber holding f a c i l i t i e s .  was  gravity  fed  into  ratios.  the  The d i s s o l v e d gas p r e s s u r e d i f f e r e n t i a l CAP)  was measured u s i n g a Novatech Designs model 300 C  tensionometer.  From AP and t h e barometric p r e s s u r e CBP), t h e T o t a l Gas CTGP) c o u l d be c a l c u l a t e d from equation 1.1.  The  Pressure  tensionometer  probe was c o n t i n u o u s l y a g i t a t e d by a B u r r e l l W r i s t A c t i o n to  fish  Shaker  prevent a i r bubbles forming on t h e t u b i n g membrane which would  prevent t h e passage o f gases p r e s s u r e o f oxygen  into  the  membrane.  was measured u s i n g a  C P O 2 )  e l e c t r o d e and meter Cmodule  PHA  930).  The  Radiometer  The  oxygen  Water  temperature  thermometer with 0.1  °C  measured u s i n g a w a l l  was  measured  gradations.  mounted  d i s s o l v e d gas oxygen:nitrogen  Barometric  mercury ratio  Fortin  CONR)  these measurements by d i v i d i n g t h e p e r c e n t 0 percent N  2  saturation.  The  percent  using  was 2  a  was  stripped mercury  pressure  was  barometer.  The  calculated  from  saturation  saturation  oxygen  meter  c a l i b r a t e d d a i l y with a i r e q u i l i b r a t e d water and oxygen water.  partial  of  by  the  oxygen  was  c a l c u l a t e d by: %0  2  =  P0  2  / 0.2094 CBP - PH 0)  2.1  2  The p e r c e n t s a t u r a t i o n o f n i t r o g e n was c a l c u l a t e d by: %N N  2  2  =  CBP + AP - P 0  i n c l u d e s Argon.  2  - PH 0) / 0.7902 CBP - PH 0) 2  2  2.2  2-2  DETERMINATION OF SWIMBADDER INFLATION THRESHOLD The  threshold  swimbladder was  TGP  required  for  inflation  water.  of swimbladder  by  pressure Fish  was  were  accomplished  anaesthetized  in  Measurement  cannulating  1:10,000  methanesulphonate CMS-222) and p l a c e d on t h e i r s i d e hammock.  the  d e t e c t e d by measuring the i n c r e a s e i n swimbladder  p r e s s u r e o f f i s h h e l d i n gas s u p e r s a t u r a t e d  swimbladder.  of  Water c o n t a i n i n g 1:15,000 MS-222 was  Tricaine  in  a  cloth  p e r f u s e d over  g i l l s by a r e c i r c u l a t i n g pump i n normal d i r e c t i o n o f water A h o l e was  made i n the s i d e o f  below the l a t e r a l with a No.  one end was The cannula  mm  bubbles  An 8 cm  length of  secured  in  were  place  Forcing  expelled  p o s i t i o n i n g o f the cannula.  out  with air the  flow. 0.5  the  teflon 1.5  cm fish  tubing cm  from  into  the  swimbladder  ensured  impermeable  Statham P23  BB  passed through  t o h o l d the f i s h t o a  piece  at  the  correct after  cannula.  A s u t u r e of c o t t o n t h r e a d was cross  through  A l s o , the f i s h were d i s s e c t e d  An 80 cm long p i e c e o f gas the cannula t o a  sutures  mouth  each experiment t o v e r i f y placement o f the  connected  the  i n t o the swimbladder with a s t e e l g u i t a r wire.  a d j a c e n t muscle CFigure 1). until  approximately  ID x WALL) with a r i g h t angle bend  guided was  fish  l i n e and mid-way along the l e n g t h o f  20 s u r g i c a l needle.  CO.56 x 0.25  the  the  nylon  pressure  the  p l e x i g l a s s r e s t r a i n i n g box open a t both ends.  transducer.  the snout front  tubing  of  The f i s h  and  used  a  clear  and  the  r e s t r a i n i n g box were then p l a c e d i n t o a darkened box with a depth of 8 cm.  The f i s h was  r e v i v e d by p e r f u s i n g the g i l l s with  fresh  14  F i g u r e 1. Diagram o f apparatus used i n the measurement o f swimbladder p r e s s u r e f o r f i s h h e l d i n a i r s u p e r s a t u r a t e d *rater. The f i s h was r e s t r a i n e d i n the box by a s u t u r e through the nose t h a t anchored i t t o a c r o s s p i e c e on the box and denied i t access t o the s u r f a c e .  water. The f i s h were allowed t o a c c l i m a t e water b e f o r e data a q u i s i t i o n began. dissolved  gas  pressure  p r e s s u r e were monitored  The  differential  with  swimbladder  and  the  every 100 seconds by a  2.3  ambient pressure,  oxygen Data  Data A q u i s i t i o n system c o n t r o l l e d by a p e r s o n a l was s t o r e d on f l o p p y d i s k s f o r l a t e r  the  partial  Translation  computer.  Data  analysis.  DETERMINATION OF PNEUMATIC DUCT RELEASE PRESSURE In s u p e r s a t u r a t e d water swimbladder p r e s s u r e i n c r e a s e d ,  making the f i s h p o s i t i v e l y buoyant.  The  pressure  r i s e u n t i l i t exceeded a t h r e s h o l d f o r v e n t i n g pneumatic  duct.  This  pressure,  p r e s s u r e CDRP) determined experience.  the  of  gas  pneumatic  To determine the p r e s s u r e t h a t c o u l d  The f i r s t method measured swimbladder  to the  release  fish  be  two  would  maintained  methods  pressure  The second method i n v o l v e d r e d u c i n g environmental gas was e x p e l l e d from the swimbladder, and  out  duct  the extent o f buoyancy the  w i t h i n the swimbladder b e f o r e v e n t i n g o f gas, used.  continued  were  directly.  pressure  calculation  until  of  duct  release pressure. 2.3.1  D i r e c t Measurement o f Pneumatic Duct Release To measure swimbladder p r e s s u r e d i r e c t l y ,  inserted  into  the  swimbladder  was  connected  the  to  t r a n s d u c e r CStatham P23 BB), as d e s c r i b e d i n s e c t i o n release  pressure  swimbladder  at  was 0.625  determined ml/min.  by  injecting  Measurements  Pressure  a  pressure  2.2.  air of  cannula  into  Duct the  swimbladder  pressure  and  time  were  a q u i s i t i o n system.  taken  every  second  using  the  pneumatic  advantages i n t h a t i t was on a f i s h i n  concert  duct.  Air  accuracy  with  in  the  2.3.2  injection  experiments  had  to  performed  determine  small  fish  was  r e l e a s e p r e s s u r e was  the  water.  difficult,  r e s t r i c t e d t o f i s h g r e a t e r than 30 g.  I n d i r e c t Measurement o f Pneumatic Duct Release A modification  several  i n gas s u p e r s a t u r a t e d  cannulating  t h e r e f o r e t h i s method was  swimbladder  e a s i l y repeated and c o u l d be  t h r e s h o l d f o r swimbladder i n f l a t i o n However,  data  S u c c e s s i v e r i s e s i n p r e s s u r e were f o l l o w e d by  r a p i d drops i n swimbladder p r e s s u r e c o r r e s p o n d i n g t o venting v i a  the  of  Harvey's  C1963)  used f o r f i s h weighing  method  Pressure for  duct  l e s s than 50 g.  This  method r e q u i r e d measurement o f the swimbladder  volume  and  then  d e t e r m i n a t i o n o f duct r e l e a s e pressure. A graduated  chamber  was  constructed  p i p e t t e t o d e t e c t volume changes i n  p r e s s u r e was placed  small  altered  inside  the  CFigure  2).  apparatus.  An  with the  a fish  anaesthetized  Initially  finely  the  i n c r e a s e d by increments o f 50 kP C380 mmHg) up t o  as  the  fish  was  pressure  was  150  The  kP.  change i n volume o f the f i s h from the i n c r e a s e d p r e s s u r e was  due  to  the  swimbladder  compression.  swimbladder must conform  to  swimbladder a t atmospheric change i n volume CdV), chamber p r e s s u r e CP ) 7  the  Since  the  gases  Boyle's  Law,  the  p r e s s u r e CV^) barometric  are known.  The  within volume  of  the  can be c a l c u l a t e d i f the pressure  relationship:  a R  d  the  17  VACUUM GAUGE  F i g u r e 2. Apparatus used t o measure the p r e s s u r e w i t h i n the swimbladder r e q u i r e d t o f o r c e gas out through the pneumatic duct f o r f i s h l e s s than SOg.  18  P  w i l l apply.  l  l  V  =  P  2  V  2  2  The volume o f gas i n the swimbladder  under  '  3  pressure  can then be d e s c r i b e d by: V S o l v i n g equations 2.3  =  V  and 2.4  for  2  P V.  2  dV P  2  - dV  2.4  gives: 2  * dV  2.5  = P  V  ±  2  "  l  P  =  swimbladder volume a t atmospheric  =  swimbladder volume a t i n c r e a s e d p r e s s u r e  =  change i n swimbladder volume  =  barometric  =  chamber p r e s s u r e  Determination o f the  DRP  pressure  was  accomplished  chamber p r e s s u r e below atmospheric  Consequently  the  P r e s s u r e was  decreasing  As the  fish  h i g h e r than the chamber p r e s s u r e and pneumatic duct.  by  pressure.  expands the swimbladder w a l l and the f u r t h e r expansion.  pressure  gas  decreased  swimbladder  musculature  swimbladder is in  restrict  pressure  expelled the  out  chamber  bubbles o f a i r were r e l e a s e d from the swimbladder, a t which the chamber p r e s s u r e and change i n  volume  swimbladder p r e s s u r e was  by:  calculated P  Po  =  l  *  V  V V  3  P3  =  swimbladder p r e s s u r e  V3  =  VI + dV  l  were  the  recorded.  is the  until time The  2.6  20 p r e s s u r e i n c r e a s e can be c a l c u l a t e d from the t o t a l volume o f fish.  Determination  of  volume  is  tedious  and  the  inaccurate.  However, the volume o f the f i s h can be c a l c u l a t e d i f i t s d e n s i t y i s known.  The d e n s i t y o f f i s h with d e f l a t e d swimbladder  most c o n s t a n t v a l u e and tends t o d e v i a t e l i t t l e . found  sockeye  variance.  smolts  to  average  Although Harvey'S  the rainbow t r o u t  density  d e n s i t y o f the f i s h a t DRP  with  can  volume o f the swimbladder a t DRP swimbladder a r e known.  The  be a  be  with  little  made  reasonable  over  deflated.  determined  divided  by  a  approximation  if  the  The  weight,  and d e n s i t y o f the f i s h with  mass  volume o f swimbladder a t DRP  C1963)  were  swimbladder  the  Harvey  g/ml,  determinations  l i m i t e d s i z e range, the v a l u e may of  1.0634  is  1.0634  no  plus  the  of  the  w i l l equal the t o t a l volume  fish.  V  FF  =  V  SB  SB  +  [  M  1  F  2 8  L 1.0634 J  The d e n s i t y i s then mass d i v i d e d by volume. D V  p  =  =  — —  T o t a l volume o f the  V* „ =  2.9 fish  Volume o f the swimbladder  S B  rT  =  Mass o f the  fish  =  D e n s i t y o f the f i s h a t  F  D  DRP  The d e n s i t y o f the f i s h can a l s o be expressed as a  lift  factor,  which i s the r a t i o o f the environmental water d e n s i t y <P > t o the e  f i s h density Cp ). f  sinking  factor.  T h i s v a l u e i s the i n v e r s e  of  Lowdes  C1942)  21  2.10 When t h i s r a t i o i s g r e a t e r than 1, t h e f i s h  will  buoyant.  lift  The  magnitude  of  the  buoyant  be  positively  is  directly  p r o p o r t i o n a l t o LF.  2.5  BEHAVIOURAL EXPERIMENTS Changes  in  the  swimbladder  s u p e r s a t u r a t i o n cause a change  in  the  volume  due  buoyancy  of  Examination o f f i s h behaviour may r e v e a l i f t h e for  this  decrease  in  density.  This  was  m o n i t o r i n g t h e v e r t i c a l movements o f f i s h . as a f u n c t i o n o f t o t a l gas  pressure  t r o u t r a n g i n g i n s i z e from 2 t o C200x47x50 cm  50  was g.  the  fish  conducted  the  observation  column  rainbow  observation  column  plywood  with  distribution  indicated  by  change  on  a  changes  i n t h e t e s t f i s h a t d i f f e r e n t l e v e l s o f TGP CFigure 3). on t h e s i d e o f  fish.  compensate  T e s t i n g depth  An  gas  accomplished  HxWxDD c o n s t r u c t e d from 3/4 i n c h  p l e x i g l a s s f r o n t was used t o observe depth  to  Markings  fish  depth.  Water o f known TGP was i n t r o d u c e d i n t o t h e o b s e r v a t i o n column f o r each t r i a l .  A s i n g l e f i s h was p l a c e d i n t h e column  time t o a c c l i m a t e t o t h e water c o n d i t i o n s and t o t h e column.  that  h o l d i n g a t t h e p r e f e r r e d depth.  may  have  resulted  The f i s h was  column with a v i d e o camera over an 8  2400 Hr).  become  Only one f i s h was used per t r i a l t o  behavioral interactions  the  and  hour  then  accustomed  avoid  group  in fish observed  period  The depth o f t h e f i s h i n t h e water was  allowed  not in  C1600  to  determined  to  19 The pneumatic duct  release  pressure  d i f f e r e n c e between  t h e swimbladder  (DRP) was pressure  equal  and  t o the  t h e chamber  p r e s s u r e a t DRP (P2). DRP  P3 - P2  2.7  The apparatus was c a l i b r a t e d r e g u l a r l y over t h e range o f p o s i t i v e and n e g a t i v e p r e s s u r e s s t u d i e d and i n d i v i d u a l v a l u e s f o r  a  fish  were c o r r e c t e d f o r d i s t o r t i o n o f t h e apparatus.  2.4  SWIMBLADDER EXPANSION Determination o f t h e change i n d e n s i t y o f a  t o swimbladder o v e r i n f l a t i o n i s accomplished  by  fish  due  measuring  the  i n c r e a s e i n volume o f t h e swimbladder and t h e f i s h . the swimbladder due  to  an  increase  i n bladder  measured i n t h e same apparatus used t o determine  Expansion o f pressure  was  t h e duct r e l e a s e  pressure f o r small f i s h . The  volume  described f o r i n d i r e c t  of  measurement  p r e s s u r e CSection 2.3.2). of swimbladder  volume  t h e swimbladder of  was  pneumatic  determined duct  as  release  A f t e r measurements f o r t h e c a l c u l a t i o n  were  taken,  t h e chamber  pressure  was  decreased and changes i n swimbladder volume recorded f o r every 10 kP (75 mmHg) r e d u c t i o n i n p r e s s u r e  from  one  atmosphere  bubbles were e x p e l l e d from t h e mouth o f t h e f i s h . the experiments  were c a r r i e d out s i m u l t a n e o u s l y  In with  until  practice the  duct  r e l e a s e p r e s s u r e work. The change i n d e n s i t y o f t h e f i s h  due  to  swimbladder  22  totflm I  DEPTH 5ML: -I METERS  2  L  Figure 3. Diagram o f the o b s e r v a t i o n column used t o monitor the depth d i s t r i b u t i o n o f rainbow t r o u t f o r d i f f e r e n t levels of TGP. T o t a l depth o f the water was 2 meters. Water flowed i n t o the column a t a r a t e o f S L/min.  23 the n e a r e s t 10 cm a t approximately  3 minute i n t e r v a l s .  depth and standard d e v i a t i o n were determined from the observations.  Capproximately  24 hours).  with the video.  Each f i s h was  r a n g i n g from 100%  the f i s h was  Depth f o r the f i s h was  CAP  observed  = 0) t o 120%  a t two CAP  =  1mm.  then  acclimate  again monitored  or more l e v e l s ISO).  of  Afterwards  removed from the column, weighed t o w i t h i n O.lg  body l e n g t h measured t o w i t h i n  mean  individual  A d i f f e r e n t l e v e l o f s u p e r s a t u r a t e d water was  i n t r o d u c e d i n t o the column, and the f i s h g i v e n time t o  TGP  The  and  24 3.0  3.1  RESULTS  RESPONSE OF SWIMBLADDER TO GAS SUPERSATURATED WATER Fish  exposed  to  gas s u p e r s a t u r a t e d  i n c r e a s e i n swimbladder pressure.  water  I f t h e water  show  TGP  an  i s high  enough, t h e swimbladder p r e s s u r e w i l l c o n t i n u e t o r i s e  until i t  exceeds a l e v e l t h a t w i l l f o r c e gas out through  the  pneumatic  swimbladder  pressure  duct. F i g u r e 4 i s a t y p i c a l example o f  i n c r e a s e f o r a f i s h h e l d i n s u p e r s a t u r a t e d water CAP = SO mmHg). mmHg.  of  P r e s s u r e w i t h i n t h e swimbladder  106.6%  rose  TGP  t o 14.1  At t h i s p r e s s u r e , gas was f o r c e d out t h e pneumatic  duct.  The sudden drop i n p r e s s u r e i s c h a r a c t e r i s t i c o f swimbladder  gas  v e n t i n g , which can a l s o be seen i n F i g u r e 5 where  duct  multiple  r e l e a s e s were c r e a t e d by i n f u s i n g a i r i n t o t h e swimbladder constant rate.  A i r i n f u s e d i n t o t h e b l a d d e r caused  i n p r e s s u r e , u n t i l a l e v e l was reached pneumatic duct.  an  at a  increase  t h a t c o u l d f o r c e open t h e  The s i m i l a r i t y between t h e p r e s s u r e s r e q u i r e d t o  r e l e a s e gas out t h e pneumatic duct  during  artificial  inflation  and d i f f u s i o n o f s u p e r s a t u r a t e d gases i n t o t h e swimbladder can be seen i n F i g u r e s 4 and 3. the  continued  swimbladder o f  After the venting o f  diffusion  of  supersaturated  the f i s h  should  i n c r e a s e i n swimbladder p r e s s u r e .  have  gas gases  resulted  However, upon  the cannula, drops o f water c o u l d be seen  CFigure into  in a  the  further  examination  occluding  4),  of  the tubing  and p r e v e n t i n g f u r t h e r measurement o f swimbladder pressure.  This  23  SWIMBLADDER P R E S S U R E V S TIME 15-10-1986  0  2  195g FISH  4 TIME  6  8  hours  F i g u r e 4. Increase i n swimbladder p r e s s u r e f o r a l°5g rainbow •trout, h e l d i n gas s u p e r s a t u r a t e d water CAP = 50 mmHg ± 2 ) . The r a p i d drop i n p r e s s u r e a f t e r 5 hours i s a s s o c i a t e d with v e n t i n g o f gas out t h e pneumatic duct.  26  Figure S . Venting o f gas out t h e pneumatic duct when a i r was i n f u s e d i n t o t h e swimbladder a t a r a t e o f 0.625 ml/min. The sharp drops i n p r e s s u r e a r e c h a r a c t e r i s t i c o f gas r e l e a s e from the swimbladder.  27 p a t t e r n was seen o f t e n and may r e s u l t from  the  sudden  drop  in  p r e s s u r e a s s s o c i a t e d with v e n t i n g o f gases. D e t e c t i o n o f a TGP t h r e s h o l d f o r swimbladder proved d i f f i c u l t due t o the long response  time  swimbladder i n f l a t i o n .  became  Often the cannula  inflation  associated  with  occluded  with  water, and changes i n b l a d d e r p r e s s u r e were i m p o s s i b l e t o d e t e c t . F i g u r e 6 shows a response f o r a  fish  held  t h r e s h o l d f o r swimbladder i n f l a t i o n .  in  More  water  than  IS  near hours  were  the  DRP.  r e q u i r e d f o r t h e p r e s s u r e i n t h e swimbladder t o exceed The i n i t i a l response o f  the  swimbladder  showed  no  consistent  t r e n d , as t h e p r e s s u r e o s c i l l a t e d between 1 and 5 mmHg. d i f f u s i o n o f gases i n t o the swimbladder i s expected a t t h e s e l e v e l s o f TGP,  most  cannula p r e v e n t i n g f r e e  movement  swimbladder  pressure  contraction  of  to  the changes i n p r e s s u r e d e t e c t e d  p r e s s u r e t r a n s d u c e r are  likely  caused  skeletal  due  of  by  muscle  to  air.  moisture  Sudden  struggling  As be by  the  in  the  changes  1966)  s u f f i c i e n t t o d i s l o d g e a water drop from o c c l u d i n g  the  the slow  movements  CMcGutheon,  the  in and  may  be  cannula.  For example, the sudden r i s e i n swimbladder p r e s s u r e a t s i x hours i s i n d i c a t i v e o f water o c c l u d i n g the cannula ( F i g u r e 6 ) .  Beyond  t h i s time p e r i o d the b l a d d e r p r e s s u r e i n c r e a s e d u n t i l i t reached a l e v e l a t 16 hours where gas duct.  Figure  7  pressures f o r the  is  the  same  was  expelled  artificially  fish.  decrease i n swimbladder p r e s s u r e  After is  out  induced each  small.  duct  the duct  pneumatic release  release,  Consequently,  the the  f i s h w i l l c o n t i n u o u s l y have an excess i n swimbladder p r e s s u r e and  28  SWIMBLADDER PRESSURE VS TIME 22-09-1986  TIME  184g  FISH  hours  F i g u r e 6. Increase i n swimbladder p r e s s u r e f o r a 184g rainbow t r o u t h e l d i n gas s u p e r s a t u r a t e d water CAP = 29 mmHg ± 2). The uneven i n c r e a s e i n p r e s s u r e over the f i r s t 8 hours i s l i k e l y due t o moisture i n the cannula.  PNEUMATIC DUCT RELEASE PRESSURE 23-09-1986  TIME  184g FISH  seconds  Figure 7 . Release o f gas out t h e pneumatic duct during i n f u s i o n o f a i r i n t o t h e swimbladder o f a 184g rainbow trout. I n f u s i o n o f a i r began a t 30 seconds and ended a t 220 seconds.  30 be p o s i t i v e l y buoyant,. The  minimum  swimbladder p r e s s u r e  AP  found  was 27  t o cause  mmHg.  an  T h i s was confirmed when f i s h were  placement  o f t h e cannula  within  below  this  and a  dissected  the  t o determine During  inflation  Commonly, f i s h h e l d i n s u p e r s a t u r a t e d  the t h r e s h o l d had l a r g e extended swimbladders.  o f the  water  above  However, a t t o t a l  gas p r e s s u r e s l e s s than 27 mmHg, t h e swimbladders were underinflated.  loss of  swimbladder.  d i s s e c t i o n i t was easy t o s e e t h e r e l a t i v e swimbladder.  in  Gas t e n s i o n s  r e s u l t e d i n a r e d u c t i o n o f swimbladder p r e s s u r e gas.  increase  obviously  As t h e r e was no o p p o r t u n i t y f o r t h e f i s h h e l d i n  the boxes t o reach t h e s u r f a c e , these animals c o u l d t h e i r swimbladders by swallowing a i r .  not i n f l a t e  When these f i s h were  held  i n water near e q u i l i b r i u m o r below, they s l o w l y l o s t gas from t h e swimbladder. The  rate  of  swimbladder p r e s s u r e i n c r e a s e and i s a f u n c t i o n o f t h e t o t a l  gas  pressure.  diffusion  gradient  determines  the  The i n f l a t i o n r a t e can be c a l c u l a t e d from t h e r i s e i n  swimbladder p r e s s u r e over CdP/dt; t h e s l o p e  time.  Plotting  o f the increase  the i n f l a t i o n  i n swimbladder  rate  pressure)  a g a i n s t the d i s s o l v e d gas p r e s s u r e d i f f e r e n t i a l CAP) r e s u l t e d i n 2  a l i n e a r r e l a t i o n s h i p CR  = 0.966) when t h e ONR Coxygen:nitrogen  r a t i o ) i s c o n s t a n t a t 0.95 CFigure 8 ) .  As t h e TGP i n c r e a s e s t h e  r a t e o f d i f f u s i o n i n t o t h e swimbladder from t h e  arterial  must a l s o i n c r e a s e .  t h e swimbladder  I t can a l s o be seen  that  w i l l l o o s e p r e s s u r e when TGP i s below e q u i l i b r i u m  system  o r below t h e  31  SWIMBLADDER INFLATION RATE AS A FUNCTION OF TGP  1.8  H  1.6 1.4 1.2  -  1 0.8 0.6  H  0.4 0.2  -  0 -0.2  -  -0.4  -  -0.6  -  -0.8  -  -1  + + "~T~ 20  40 DISSOLVED GAS PRESSURE  60  80  mmHg  F i g u r e 8. Rate o f i n c r e a s e i n swimbladder p r e s s u r e (mmHg per hour) f o r rainbow t r o u t h e l d i n different l e v e l s of gas s u p e r s a t u r a t e d water. The ONR was constant f o r a l l the data points, a t 0.95.  32 t h r e s h o l d f o r d i f f u s i o n o f gases i n t o the b l a d d e r CAP < f o r an ONR o f approximately The  threshold  1.0).  f o r swimbladder  dependent on the P 0 o f t h e water. 2  m a i n t a i n a constant the  P0  2  tended  inflation  with  t h e TGP  throughout  experiments, keeping the ONR r e l a t i v e l y constant.  p a r t i a l pressures o f P0 , 2  in  with  oxygen,  excess  which  o f 250 mmHg  s l i g h t l y below e q u i l i b r i u m .  the  To examine the  e f f e c t t h a t changing the ONR would have on swimbladder the water was s u p e r s a t u r a t e d  also  o f TGP; consequently  2  t o increase  is  I t was n o t p o s s i b l e t o  P 0 over a wide range  oxygen p a r t i a l p r e s s u r e s  27 mmHg  inflation,  resulted i n and  nitrogen  At higher  levels  the t h r e s h o l d TGP f o r h y p e r i n f l a t i o n o f t h e swimbladder  increased.  For example, a t a P 0 o f 250 2  mmHg  t h a t caused an i n c r e a s e i n bladder pressure  the threshold  was g r e a t e r  AP  than  40  mmHg. Although  the  variation  t h r e s h o l d f o r d i f f u s i o n o f gas  in  t h e ONR  i n t o the swimbladder, i t  s i g n i f i c a n t l y a f f e c t the r a t e o f i n f l a t i o n . with the same P0 , 2  Each s e r i e s had  Five  resulted series  d i f f e r e n t oxygen l e v e l s CTable 1).  points in a  Linear  2  2  not  o f data  s i m i l a r l e v e l s o f P0 .  r e g r e s s i o n o f dP/dt on AP with P 0 was c a l c u l a t e d  the  did  Choosing data  showed t h a t an i n c r e a s e i n AP  corresponding increase i n i n f l a t i o n rate. p o i n t s were used.  altered  f o r the five  Analysis o f covariance  showed  no s i g n i f i c a n t d i f f e r e n c e between the r e g r e s s i o n c o e f f i c i e n t s CF = 1.0305, P > 0.50).  Changing the ONR o f the water r e s u l t s i n  s e r i e s o f e q u a t i o n s d e s c r i b i n g dP/dt  against  AP  that  a  are a l l  33  x P0  2  ± s. e.  n  mmHg  152.2 158.9 168.9 274. 9 322. 2 common  b mmHg/Hr  0. 462 0.773 0.455 2.641 1.237  15 8 7 7 9  0.0589 0.0404 0.0462 0.0383 0.0484 0.0480  Table 1. S t a t i s t i c s f o r r e g r e s s i o n o f r a t e o f swimbladder i n f l a t i o n on d i s s o l v e d gas t e n s i o n f o r f i v e l e v e l s o f PO2* ^ the PO2 c o u l d not be kept constant over the whole range o f t o t a l gas p r e s s u r e s t e s t e d , o n l y those data p o i n t s were chosen t h a t had s i m i l a r P 0 . The standard e r r o r term expresses t h e d e v i a t i o n i n PO2 o f these data p o i n t s . The c o e f f i c i e n t c a l c u l a t e d by linear r e g r e s s i o n i s b. 2  34 p a r a l l e l , but o f f s e t from one another depending on the P0 . 2  M u l t i p l e l i n e a r r e g r e s s i o n performed on the swimbladder i n f l a t i o n r a t e d a t a showed a s i g n i f i c a n t i n t e r r e l a t i o n s h i p o f t h e independent v a r i a b l e s CAP,  P0 ,  dependent v a r i a b l e , dP/dt. CP  4  6  8  << 0.001).  2  Weight and  F  for  the  Temperature) regression  on  was  87.42S  The p a r t i a l r e g r e s s i o n c o e f f i c i e n t s f o r AP  = 18.136; P << 0.001) and P 0  2  CT =  -6.567; P < 0.001)  a s i g n i f i c a n t r e l a t i o n s h i p with dP/dt.  Temperature  the  CT  indicated  was  varied  l i t t l e throughout each experiment C< 0.3°C), but ranged over  the  d u r a t i o n o f the study from 8.0  not  t o 16.3°G.  However,  it  found t o s i g n i f i c a n t l y a f f e c t the r a t e o f swimbladder  was  inflation.  The p a r t i a l r e g r e s s i o n c o e f f i c i e n t f o r temperature was 1.4507 > 0.1).  F i s h weight d i d not have a s i g n i f i c a n t e f f e c t on  Trout ranged i n s i z e from 45 t o  245g.  The  partial  CP  dP/dt.  regression  c o e f f i c i e n t was -0.8605 CP > 0.2). When temperature and f i s h  weight  r e g r e s s i o n a n a l y s i s on the dP/dt data, the r e l a t i o n s h i p between r a t e o f  were  the  excluded  equation  swimbladder  describing  inflation  d i s s o l v e d gas t e n s i o n and the p a r t i a l p r e s s u r e o f oxygen dP/dt  =  0.04142 CAP)  -  0.007316 CP0 ) 2  F f o r t h e r e g r e s s i o n was 172.795 CP Although, P 0 AP  2  determines  2  7  Q  «  +  R  2  determines t h e t h r e s h o l d f o r swimbladder the  magnitude  of  the  on  diffusion  the  was:  0.3634  0.001).  from  =  3.1 0.832.  inflation,  gradient  and  consequently t h e r a t e o f p r e s s u r e b u i l d u p w i t h i n the swimbladder. The  data  collected  on  swimbladder  inflation  rate  35 (dP/dt) r e v e a l s t h a t t h e r e i s a l e v e l o f TGP  t h a t does  t o an i n c r e a s e or decrease i n swimbladder pressure. of  TGP  is  the  threshold  for  swimbladder  not This  ( F i d l e r , 1985)  i s presented  the t h r e s h o l d l i n e l e a d  to  i n F i g u r e 9.  swimbladder  those below the t h r e s h o l d l i n e l e a d t o dP/dt  data  points  swimbladder p r e s s u r e pressure.  are  denoted  C l e a r l y data  for  collected  this  above whereas  for  The  increases in  study  in  swimbladder support  the  t h a t w i l l f o r c e a i r through  the  v a l i d i t y o f F i d l e r ' S C1985) t h r e s h o l d  3.2  levels  deflation.  decreases  in  equation  overinflation,  positive  and n e g a t i v e  TGP  bladder  level  overinflation.  Comparison o f the data from t h i s study and the t h r e s h o l d 1.2  lead  equation.  PNEUMATIC DUCT RELEASE PRESSURE The  threshold pressure  pneumatic duct  i s dependent on the s i z e o f the f i s h CFigure  Small f i s h have higher duct r e l e a s e p r e s s u r e s  than  large  Within the s i z e group 1 - 10 g t h e r e i s a steep i n c r e a s e as f i s h become s m a l l e r .  There i s l e s s d i f f e r e n c e  in  seen f o r a r t i f i c i a l l y swimbladder and supersaturated A  induced  release  DRP  pressures  release from  DRP  pressures. infusing  observed  fish. in  f i s h l a r g e r than approximately 30 g; although i t i s s t i l l t h a t l a r g e r f i s h have lower duct  air  10).  DRP among  evident  This  was  into  the  for  fish  held  the  data  forms  in  water.  logarithmic  s t r a i g h t l i n e ( F i g u r e 11).  transformation  of  L i n e a r r e g r e s s i o n on the  a  transformed  36  SWIMBLADDER OVERINFLATION DATA TGP VS WATER P02  140 130 120 110  0>  I  E E  t  H  100  90  -f  80  -j  ++  70 - i  Ui  I  0.  P  60 50  + +  -j  -j  40-j i  30 H 20 -|  + +  + + +  +  +  +  + % 1 ~  SWIMBLADDER OVERINFLATION THRESHOLD  10 -j ™i—r  140  160  ~ T ~ T  180  ~"i—r—r~ i—i—v—i 200  220 WATER P02  240  260  i—i—r—r—r 280  300  T"  320  340  mmHg  F i g u r e 9. Plot- o f -the t o t a l gas p r e s s u r e t h r e s h o l d equation d e r i v e d by F i d l e r C19855 as a f u n c t i o n o f t h e water PO2. Data from t h i s study i s a l s o p l o t t e d . + i n d i c a t e s dP/dt was p o s i t i v e and the swimbladder i n f l a t e d i n d i c a t e s dP/dt was n e g a t i v e and the swimbladder d e f l a t e d  37  DUCT RELEASE PRESSURE VS WEIGHT FOR RAINBOW TROUT  1  X  E E  &  D OT bi cc a.  1 a  d  30 -IX  20  # + +  -  +  Q 10  H  0  4 0  ~7  1  T  40  . ++  1  1 BO  +  Method 1  FISH WEIGHT  +  +  1  T  120 g  + +  i  160 X  1  1 200  r 240  Method 2  F i g u r e 10. The r e l a t i o n s h i p between t h e i n t e r n a l swimbladder p r e s s u r e r e q u i r e d t o f o r c e gas out the pneumatic duct and the weight o f the f i s h f o r rainbow t r o u t CSalmo gairdneri"). Method 1 r e f e r s t o data p o i n t s t h a t were c o l l e c t e d by i n f u s i n g a i r into the swimbladder a t 0.623 ml/min. Method 2 r e f e r s t o data points o b t a i n e d u s i n g t h e method o f Harvey C1963).  38  DUCT RELEASE PRESSURE VS WEIGHT FOR RAINBOW TROUT  1  2  3  5  10 FISH WEIGHT  +  Method 1  20  30  50  100  200  300  g X  Method 2  F i g u r e 11. A plot, o f the l o g a r i t h m i c a l l y transformed data showing the r e l a t i o n s h i p between the pneumatic duct release p r e s s u r e and t h e weight o f the f i s h . Method 1 and method 2 r e f e r t o methods d e s c r i b e d on F i g u r e 10.  39 data gave t h e equation: DRP R  2  =  Vt " ° -  *  2 8 8  60  3.2  f o r t h e equation 0.842. The DRP shows a response r e l a t e d t o the minimum  of t h e pneumatic duct as d e s c r i b e d by t h e surface tension.  Laplace  The pneumatic duct r a d i u s t h a t  radius  equation  for  corresponds  the DRP can be c a l c u l a t e d by equating t h e DRP e q u a t i o n  to  with  the  L a p l a c e equation. DRP Vt" 0  P  * 60  2 8 8  =  - P  3.3  - -2_  3.4  2  S o l v i n g t h e equation f o r r C^nm) and u s i n g a  surface  tension  of  74.22 dynes/cm, g i v e s : r  =  Vt * 0  During experiments  to  2 8 8  * 18.6  determine  3.S pneumatic  duct  r e l e a s e p r e s s u r e u s i n g H a r v e y s C1963) method, s e v e r a l f i s h  were  not observed t o r e l e a s e gas out t h e mouth. became g r o s s l y c o r p u l e n t from until  bubbles o f a i r were  the  observed  Presumably t h e swimbladder o f  these  p r e v e n t i n g escape o f gas out t h e  the  In each case t h e f i s h  swimbladder to  escape  gases from  individuals  pneumatic  duct.  expanding the  had In  anus.  ruptured, each  of  these cases the f i s h weighed l e s s than 10 g.  3.3  SVIMBLADDER The  EXPANSION  volume  of  the  swimbladder  i s related  t o the  40 p r e s s u r e w i t h i n t h e swimbladder.  At low  swimbladder  pressures,  f u r t h e r increases i n pressure lead t o r e l a t i v e l y large  increases  i n volume.  T h i s can be seen i n F i g u r e 12 as t h e f l a t  part  the curve.  Thus, t h e most r a p i d  change  before a large buildup  i n pressure  pressures  i n volume  t h e change  i n volume  will  occur  occurred.  At  higher  has  i s reduced,  t h e membrane  i s r e s t r i c t e d by  tissues.  The b l a d d e r p r e s s u r e i s o n l y a l l e v i a t e d by  more  r e l e a s e p r e s s u r e i s reached.  than  swimbladder  surrounding  F i g u r e 12 shows t h e  r e l a t i o n s h i p f o r a 9.5 g rainbow t r o u t . volume o f t h e swimbladder  and  as  expansion  gas o u t t h e pneumatic duct.  of  body  release  pressure/volume  I t can be seen t h a t doubles  of  before  the  the  duct  Although t h e d o u b l i n g o f t h e volume  g i v e s an i n d i c a t i o n o f t h e d e n s i t y change  of  the f i s h ,  i tis  dependent on t h e i n i t i a l volume o f t h e swimbladder, which may underinflated or overinflated. must be determined  Thus, t h e maximum  volume  be  change  i n r e l a t i o n t o t h e t o t a l volume o f t h e f i s h .  P l o t t i n g the calculated density pressure reveals that small  fish  will  at  t h e duct  experience  the  change i n d e n s i t y from n e u t r a l buoyancy CFigure 13).  release largest  Regression  a n a l y s i s on t h e l o g transformed data r e s u l t e d i n t h e equation: DENS R  2  =  0.931 * VT  0  0  1  3.6  7  f o r t h e equation i s 0.725. The e x p o n e n t i a l r e l a t i o n s h i p o f t h e data i n d i c a t e s t h a t  s m a l l f i s h w i l l have a tremendous buoyancy change b e f o r e e x p e l l e d out t h e pneumatic duct.  The  flattening  of  gas i s  the  curve  41  VOLUME CHANGE WITH INCREASED PRESSURE FOR A 9.5g RAINBOW TROUT  40 35  t  I  E E  30 - t  DC Ui  o o  25 -i  2  20 H  o  15  Ui  a  V) (0 Ul  a a.  10 5-4  "~T~  0.2  0.4  0.6  I 0.8  VOLUME OF SWIMBLADDER ml  F i g u r e 12. The r e l a t i o n s h i p between t h e i n t e r n a l p r e s s u r e and the volume o f t h e swimbladder f o r a 9.5g rainbow t r o u t .  42  F i g u r e 13. Density o f rainbow t r o u t a t the t h r e s h o l d pressure f o r v e n t i n g o f gas through the pneumatic duct as a function of the f i s h weight.  43 above 20 g i n weight s i g n i f i e s a s m a l l e r change i n buoyancy t h i s s i z e range  of  fish.  Figure  14  shows  e x p e r i e n c e d by a f i s h when t h e swimbladder  the  lift  pressure  for  factor  equals  the  total  gas  DRP.  3.4  BEHAVIOURAL RESPONSE The mean depth o f f i s h  i s dependent  p r e s s u r e and t h e s i z e o f t h e f i s h .  Small  grams compensate f o r i n c r e a s i n g TGP  by  on  the  fish,  seeking  less  than  greater  10  depth.  L a r g e r f i s h show a depth d i s t r i b u t i o n t h a t appears independent o f the down  TGP.  Many f i s h spent long p e r i o d s o f time  the  column.  equilibrium. the  This  was  clearly  evident  at  up  TGP  and near  Consequently t h e mean depth was near t h e c e n t r e o f  column C100 cm depth).  I n c r e a s i n g t h e TGP  c o n s t a n t e f f e c t on f i s h above 40 column,  swimming  g;  some lower and some d i d n o t  some  were  change  d i d not higher  their  depth.  depth f o r  Although many o f these f i s h would s t i l l  and down t h e l e n g t h o f t h e column,  a  i n the  mean  However, f i s h below 10 g i n weight e x h i b i t e d a deeper i n c r e a s i n g TGP.  have  swim  up  t h e r e l a t i v e frequency o f f i s h  i n t h e t o p s e c t i o n s o f t h e water column decreased with  increased  t o t a l gas p r e s s u r e . M u l t i p l e r e g r e s s i o n on mean depth as a f u n c t i o n and  weight  resulted  in  r e g r e s s i o n was 5.098 C P  R  a  non-linear <  0.01),  response.  and  R  2  was  F  of  AP  f o r the  0.338.  The  n o n - l i n e a r r e s u l t was due t o s e v e r a l f i s h h o l d i n g near t h e bottom of t h e column a t a l l t o t a l gas p r e s s u r e s t e s t e d .  As t h i s i s most  44  F i g u r e 14. The lift factor p r e s s u r e a t the DRP as a f u n c t i o n  calculated for a swimbladder o f the f i s h weight.  45 l i k e l y a behaviour t h a t i s independent o f the t o t a l the  gas p r e s s u r e ,  d a t a was n o r m a l i z e d by comparing the change i n depth  weight and AP.  the  A m u l t i p l e l i n e a r r e g r e s s i o n on the data r e s u l t e d  i n the h i g h e s t v a l u e o f Fj F was 18.106 CP., _„ < was 0.521.  to  The  g r o s s mean  depth  for  0.001)  a l l sizes  of  The mean depth Ccm)  R  fish  e q u i l i b r a t e d water was then c a l c u l a t e d and added t o the i n the equation.  and  in  constant  i s d e s c r i b e d by:  Depth = 0.532CAP) - 0.0419CVt) -0.0137CAP*Vt) + 110.1 A  comparison  of  the  compensation depth f o r F i g u r e 15. gases  Hydrostatic  in  solution.  depth  distribution  swimbladder pressure The  2  equation  overinflation will  compensation  3.7  maintain depth  to  is  the  shown  in  supersaturated  is  where  the  h y d r o s t a t i c p r e s s u r e reduces the excess d i s s o l v e d gas p r e s s u r e t o the  t h r e s h o l d f o r swimbladder  inflation  CAP  U  = 27 mmHg).  As  the  TGP i n c r e a s e s , the depth r e q u i r e d t o m a i n t a i n the d i s s o l v e d  gases  in s o l u t i o n also increases.  I t can be seen t h a t l a r g e f i s h  spend  more time above the compensation depth a t h i g h l e v e l s o f AP  than  small  fish. Although the model i n d i c a t e s t h a t  e x p e r i e n c e swimbladder  overinflation,  i n d i c a t i n g p o s i t i v e buoyancy a the  many  large  fish  do  behaviour  patterns  were observed d u r i n g the study.  AP o f 116 mmHg a 50 g f i s h h e l d p o s i t i o n i n t h e top c o r n e r o b s e r v a t i o n column f o r long p e r i o d s o f time.  The  not  tail  At of and  d o r s a l f i n o f t h e f i s h broke the s u r f a c e as i t h e l d p o s i t i o n with the  head down and the t a i l s l o w l y o s c i l l a t i n g .  At  a  AP  of  80  F i g u r e IS. Depth d i s t r i b u t i o n f o r rainbow t r o u t CSalmo gairdneri^ as a f u n c t i o n o f the dissolved gas pressure d i f f e r e n t i a l CAP) and the weight o f the f i s h . The compensation depth r e q u i r e d t o a l l e v i a t e d i f f u s i o n o f gas i n t o the swimbladder i s a l s o p l o t t e d CAP = 27mmHg). U  47 mmHg a 35 g f i s h was  observed  to  hold  position  in  column a t a depth o f 40 cm with the head down and T h i s body posture i s buoyant.  Large  indicative  fish  appear  s u p e r s a t u r a t e d water, but do  of to  not  problem by s e e k i n g g r e a t e r depth. lift  i s s m a l l and  i t plays  d i s t r i b u t i o n o f the  fish.  no  fish be  that  tail are  positively  compensate  for  in  water  beating. positively  buoyant the  The magnitude o f  role  the  determining  in  buoyancy  the the  buoyant depth  48  4.0  DISCUSSION  When exposed t o water s u p e r s a t u r a t e d  with  atmospheric  gases, rainbow t r o u t e x h i b i t an i n c r e a s e i n the i n t e r n a l p r e s s u r e o f the swimbladder.  The t h r e s h o l d f o r  gas d i f f u s i o n  into the  swimbladder e x i s t s a t a AP o f 27 mmHg when the water P 0 mmHg.  I n c r e a s i n g the p r o p o r t i o n o f oxygen  i n c r e a s e the t h r e s h o l d .  is  2  i n t h e water  T h e r e f o r e , a h i g h e r AP i s  will  required f o r  d i f f u s i o n o f gases i n t o the swimbladder a s the P 0 i n c r e a s e s . 2  hyperoxic water CP0  2  160  In  = 250 mmHg) the t h r e s h o l d AP f o r swimbladder  i n f l a t i o n i s approximately 45 mmHg. Although TGP i s  the principal  component  determining  dP/dt, the c o n s t i t u e n t gases d i s s o l v e d i n the water a l s o have effect  on  diffusion  the rate  of inflation  coefficient  f o r oxygen  n i t r o g e n CKrogh, 1919). an i n c r e a s e i n dP/dt.  o f t h e swimbladder. i s greater  than  The  that f o r  An i n c r e a s e i n t h e ONR should r e s u l t i n However, t h i s i s a s m a l l  factor  and  a r t e r i a l P 0 has g r e a t e r b e a r i n g on the r a t e o f i n f l a t i o n . i s due t o t h e lower l e v e l  of P0  2  i n the a r t e r i a l  r e l a t i o n t o the water, and i s expressed than  as the F  one CRandall  a t the t i s s u e s p r e v e n t s the 0 fully  equilibrating  with  2  level in the  the f i s h  water,  system i n ratio.  and Daxboeck,  D i f f u s i o n r e s i s t a n c e a t the g i l l s and the consumption  unlike  the This  2  r a t i o i s always l e s s  an  The  1984).  o f oxygen  tissues  from  nitrogen.  Consequently the a r t e r i a l PO^ i s lower than the water P0^ and the  49 t h r e s h o l d f o r blood gases t o d i f f u s e i n t o the swimbladder i s a t 100%  TGP.  P0  a l t e r the t h r e s h o l d .  2  and  The  F r a t i o w i l l a l s o vary with the During  flow i s reduced CRandall and g r a d i e n t between water and Equation 1.2  Daxboeck,  blood  C F i d l e r , 198S)  prediction.  1984),  predicts  The  e q u a t i o n shows a s t r o n g e f f e c t o f P 0  will also  2  the t h r e s h o l d AP  gill  and  the  oxygen  a  threshold  TGP  convergence of a  on the  2  for  of  the  data  threshold.  The  threshold;  swimbladder  for  an  overinflation  increase. The  diffusion  i n f l u e n c e d by the ambient  of  gases  through  temperature.  the  tissues  Increasing  r a i s e s the d i f f u s i o n c o e f f i c i e n t CVelty e t . a l . ,  r e g r e s s i o n c o e f f i c i e n t was  positive.  The  1984).  the c o e f f i c i e n t was  r e l a t i v e l y l a r g e , and  significant.  positive  The  that  rises  in  partial  standard  In  error  this  partial around  the c o e f f i c i e n t was regression  temperature  increase  is  temperature  study, the m u l t i p l e l i n e a r r e g r e s s i o n a n a l y s i s showed the  indicates  water  the data from t h i s work agrees  p o i n t s onto a l i n e i n d i c a t e s the e x i s t a n c e  increase i n P0  the  water  increases.  f o r swimbladder o v e r i n f l a t i o n , and w e l l with F i d l e r ' s  hyperoxia  ambient  not  not  coefficient the  rate  of  swimbladder o v e r i n f l a t i o n . The f i s h size.  r a t e o f swimbladder i n f l a t i o n i s a l s o  The  affected  lower s u r f a c e area t o volume r a t i o of the  i n l a r g e f i s h causes a  slower  increase  d i f f u s i o n g r a d i e n t remains constant,  the  in  pressure.  rate  of  bladder If  increase  volume w i l l be dependent on the s u r f a c e area t o volume  by  ratio  the in of  50 the  bladder.  The  large  surface  area  c o r r e s p o n d i n g t o the swimbladder o f a  to  small  volume  fish,  ratio,  will  more r a p i d l y than the swimbladder o f a l a r g e f i s h .  expand  Over the s i z e  range o f f i s h used i n t h i s study, a c l e a r r e l a t i o n s h i p was established.  never  However, the f i s h were a l l g r e a t e r than 40g and t h e  e f f e c t of the surface  area  to  volume  ratio  d i s c e r n a b l e a t much s m a l l e r s i z e s when  the  may  only  ratio  become  becomes  much  greater. Although accumulation o f salmonids has been 1958;  Fahlen, 1971;  attributed  to  gas  shown  by  gas  several  the  swimbladder  researchers  supersaturation.  l i n e a r r e l a t i o n s h i p o f dP/dt with  They the  had  never  been  proposed  that  swimbladder.  AP  of  CWittenberg,  Sundes et. a l . , 1958), i t has  salmonids a c t i v e l y s e c r e t e gas i n t o the  in  indicates  However, that  blood  gases d i f f u s e down a c o n c e n t r a t i o n g r a d i e n t i n t o the  swimbladder  when rainbow t r o u t a r e h e l d i n s u p e r s a t u r a t e d water.  The  layers of  the  swimbladder  diffusion barrier to  gases  are is  arranged exterior  such to  the  that  tissue  the  main  blood  supply  CLapennas and Schmidt-Nielsen, 1977; M o r r i s and A l b r i g h t ,  1979).  Consequently, gas exchange i s not r e s t r i c t e d between the v a s c u l a r system and the swimbladder.  However, movement o f  gas  into  the  swimbladder i s slow. The s t r u c t u r e o f the salmonid swimbladder a l s o suggests t h a t movement o f gas must be by d i f f u s i o n . of the membrane a r e simple.  The component  layers  The simple v a s c u l a r arrangement  a l l o w d i f f u s i o n , but i s not complex enough t o  produce  will  secretion  31 o f gas i n t o the t r o u t bladder  C J a s i n s k i , 1963).  The i n a b i l i t y o f  t r o u t and salmon t o s e c r e t e gas i n t o t h e swimbladder demonstrated by Harvey C1963) and T a i t C1956). no change i n swimbladder volume  or  a  is  further  They found e i t h e r  decrease  in  swimbladder  volume i n experiments where f i s h were prevented from r e a c h i n g t h e water s u r f a c e .  Harvey C1963) a l s o found  held  in  water with low oxgen t e n s i o n (2 ppm) showed a r a p i d r e d u c t i o n  in  the swimbladder oxygen content.  that  sockeye  Presumably, t h e oxygen  diffused  out o f t h e swimbladder t o a r e g i o n o f lower oxygen t e n s i o n . C o n f l i c t i n g r e s u l t s i n the l i t e r a t u r e on inflation  of  the  swimbladder  c o n d i t i o n s may be e x p l a i n e d  during  by TGP.  the  similar  relative  experimental  I t i s l i k e l y the d i f f e r e n c e s  i n s u p e r s a t u r a t i o n o f t h e water s u p p l i e s used by t h e  researchers  t h a t has l e a d t o d i f f e r e n c e s i n r e s u l t s . Diffusion  of  supersaturated  blood  swimbladder causes an i n c r e a s e i n pressure. rise until  gases The  i t reaches a t h r e s h o l d f o r r e l e a s e  pneumatic duct.  into  pressure  of  gas  DRP v a l u e s f o r f i s h l e s s than l O g , i n d i c a t e t h a t  The very a  will  out t h e  There i s a l o g a r i t h m i c r e l a t i o n s h i p between  f i s h s i z e and the pneumatic duct r e l e a s e pressure.  the  the high  considerable  pressure  b u i l d u p w i l l occur w i t h i n t h e swimbladder b e f o r e gas i s  vented.  I t has been p o s t u l a t e d  sphincter  muscle.  s p i n c t e r present  However,  i n sockeye.  that Harvey  The duct  DRP  i s controlled  C1963)  found  no  by  a  obvious  i s h i g h l y convoluted  and  F i d l e r C1984) suggested t h a t t h e DRP may be a f u n c t i o n o f s u r f a c e t e n s i o n f o r c e s and t h e minimum r a d i u s o f t h e pneumatic duct,  and  52 •therefore conform t o t h e L a p l a c e through  t h e duct  will  occur  swimbladder i s s u f f i c i e n t of t h e duct.  Equation  C1.3).  i f t h e gas  Gas  pressure  passage in  t o overcome t h e s u r f a c e t e n s i o n  forces  The r a d i u s o f t h e pneumatic duct w i l l determine t h e  minimum p r e s s u r e r e q u i r e d t o overcome t h e s u r f a c e t e n s i o n and a l l o w gas dimension  the  to  move  along  t h e duct.  Thus,  o f t h e duct i s t h e minimum diameter,  change with t h e development o f t h e f i s h .  the  forces critical  which i s l i k e l y t o  As t h e f i s h  grows t h e  r a d i u s o f t h e pneumatic duct i n c r e a s e s and duct r e l e a s e  pressure  decreases.  a  I f f i s h are held i n supersaturated  fish will  maintain  a  high  whereas a l a r g e r f i s h w i l l  pressure continuously  water,  small  within  the  swimbladder;  vent  gas  and  release  swimbladder pressure. The L a p l a c e Equation C1.3) can be used t o c a l c u l a t e t h e probable r a d i u s o f t h e pneumatic duct. pneumatic  duct  radius  controlling  I t was release  found  of  gas  swimbladder was a f u n c t i o n o f weight r a i s e d t o a power  that  the  from  the  o f 0.29.  From t h e l e n g t h and weight measurements on rainbow t r o u t made i n t h i s study, t h e l e n g t h was found t o be r e l a t e d t o to a  power  of  0.32.  The  similarity  weight  i n t h e two  i n d i c a t e s t h a t t h e r a d i u s o f t h e pneumatic duct i s  raised  exponents  approximately  proportional t o the length o f the f i s h . The r e l e a s e o f gas out t h e pneumatic duct i s dependent on a  differential  pressure  between  the  p r e s s u r e and t h e ambient water pressure.  internal However,  swimbladder fright  causes t h e r e l e a s e o f gas from t h e swimbladder o f sockeye  also salmon  53 CHarvey, 1963). gas bubbles. physostomes  When s t a r t l e d f i s h d i v e and r e l e a s e a  The r e s u l t i s an the  smooth  increase  muscle  of  in  the  fish  trail  density.  swimbladder  wall  i n n e r v a t e d by n o r a d r e n e r g i c f i b e r s CFange, 1976; Fahlen e t . 1965).  Loss o f gas induced by f r i g h t i s not a simple r e l e a s e  gas h e l d under p r e s s u r e i n t h e bladder. f o r c i b l y from the swimbladder  by  of In is al., of  Instead, gas i s e x p e l l e d  contraction  of  the  circular  muscles o f the swimbladder i n response t o a d r e n a l i n , which causes a reduction i n the cross s e c t i o n a l 1963). gas,  area  CBrawn,  Although salmonids have the a b i l i t y t o i t  is  a  sympathetic  swimbladder  of  the  supersaturated  water  not  to  response and the bladder does not  The  induce  release  the  Harvey,  swimbladder  induced  overinflation  u n t i l the DRP  vent  response  Consequently,  appears  1964;  by  the  fright. due  to  sympathetic  excess  pressure  i s reached. swimbladder  i n t e r n a l pressure. a t low p r e s s u r e s .  will  expand  with  an  increase  The expansion o f the swimbladder i s At low swimbladder p r e s s u r e the  s u r r o u n d i n g t i s s u e t e n s i o n i s low.  As the  volume  in  greatest  membrane continues  and to  expand, f u r t h e r expansion i s r e s t r i c t e d by the reduced compliance o f t h e a d j a c e n t t i s s u e and musculature. leads to a large buildup i n  pressure  The r e s t r i c t e d expansion  with  a  small  change  in  volume. The change i n volume, a s s o c i a t e d with  the  p r e s s u r e i n c r e a s e , causes an i n c r e a s e i n buoyancy. s h i p between p r e s s u r e and volume  of  the  swimbladder  The r e l a t i o n -  swimbladder  indicates  54 t h a t t h e f i s h w i l l e x p e r i e n c e a buoyant f o r c e degree o f swimbladder o v e r i n f l a t i o n . greatest release  when  the  swimbladder  dependent  on  The buoyant f o r c e  pressure  the  will  approaches  the  be duct  pressure. The f i s h used i n t h i s study experienced a buoyant f o r c e  b e f o r e swimbladder gas was vented. related.  Smaller f i s h experience the greatest l i f t .  observations  water s u b s t a n t i a t e  Work on rainbow t r o u t h e l d i n 150%  TGP  showed  Abnormal expansion symptoms o f GBT  a  supersaturated  similar  of  the  swimbladder  after  the  fish  i n f l a t e d t h e i r swimbladders.  were  Stroud  one  free  et.  findings. at  greater  CShirata,  was  of  1966). the  swimming  al.  C1975)  e x h i b i t e d abnormal buoyancy.  observed t o  at  float  the  surface.  r e v e a l e d t h e swimbladder t o be l a r g e and  be  continuously  compensated  f o r by  the  g r e a t e r depth where t h e h y d r o s t a t i c pressure  Either  i t can will  r e t a i n s the supersaturated  gas i n s o l u t i o n CHarvey,  pressure  has  fish  hydrostatic  been  shown  force i t can  swim  to  compress  Seeking depth  that  hydrostatic  were  the  buoyant  of b e n e f i t t o the f i s h i n  increased  the  levels  fish  of  a  fish.  swim t o o f f s e t t h e buoyancy o r  swimbladder and o b t a i n n e u t r a l buoyancy.  that  distended.  Swimbladder o v e r i n f l a t i o n w i l l cause t h a t must  had  found  The  Dissection  main  and  p r i o r t o death, j u v e n i l e salmonids h e l d i n a c u t e l y l e t h a l of supersaturation,  size  salmonids  these water  response  is  Literature  o f abnormal p o s i t i v e buoyancy i n j u v e n i l e  caused by gas s u p e r s a t u r a t e d  than  However, t h e e f f e c t  will  a  the be  pressure  also  1975).  The  to  alleviate  S3 symptoms o f GBT  CVeitkamp  and  exposed t o a l e t h a l l e v e l o f  Katz,  gas  1980).  supersaturation  depths, d i e d most q u i c k l y i n shallow cages deep cages C K n i t t e l et.  al.,  Caged  1980).  and  Depth  steelhead  at  different  most  slowly  provides  in  protection  a g a i n s t s u p e r s a t u r a t i o n by compensating f o r the excess  dissolved  gas pressure. Depth limited to  compensation  small  fish;  for  fish  excess  below  TGP  lOg  i n c r e a s e i n depth with i n c r e a s e s i n TGP.  is  showed  a  behaviour  a  consistent  The response i s  likely  due t o the h i g h swimbladder p r e s s u r e s r e q u i r e d f o r v e n t i n g o f the pneumatic duct. changes  in  The  density,  high  internal  forcing  swimbladder o v e r i n f l a t i o n .  the  pressures fish  to  lead  to  large  compensate  for  To m a i n t a i n n e u t r a l buoyancy the f i s h  must seek depth t o compress the swimbladder. Although l a r g e f i s h e x p e r i e n c e a density  from  swimbladder  overinflation,  a f f e c t e d by changes i n d e n s i t y .  over  behaviour. i n pressure  a  wide  range  they  decrease  are  also  in less  Harvey and Bothern C1972) showed  t h a t l a r g e r f i s h Cgreater than 20g) a r e position  smaller  of  capable  pressures  of  maintaining  without  altering  Sockeye showed no change i n behaviour f o r an i n c r e a s e equal  increases e l i c i t e d  to a  3.5  m  maximal  depth,  but  response.  subsequent However,  pressure  changes  in  behaviour o f s m a l l e r sockeye were r e a d i l y apparent as soon as the p r e s s u r e changed.  Larger f i s h  b e t t e r a b l e t o compensate  are  stronger  f o r changes i n  swimmers  density.  and  are  Consequently  they e x h i b i t l e s s change i n depth when p o s i t i v e l y buoyant due  to  56 gas s u p e r s a t u r a t i o n . p u b l i s h e d data.  These f i n d i n g s appear t o be c o n s i s t e n t with  A study on two year o l d rainbow  trout  showed t h a t the mean swimming depth o f f i s h h e l d was not s i g n i f i c a n t l y d i f f e r e n t from f i s h CLund  and  Heggberget,  1985}.  In  in  fact,  s u p e r s a t u r a t e d water showed a tendency t o l e v e l than f i s h i n e q u i l i b r i u m water. was  in  117.3%  TGP  equilibrium fish  swim  water  exposed  at  a  A c t i v e depth  to  shallower  compensation  i n s i g n i f i c a n t i n rainbow t r o u t o f t h i s s i z e . Movement t o a g r e a t e r  depth  is  a  passive  s i n c e the a b i l i t y t o d e t e c t s u p e r s a t u r a t i o n by f i s h CVeitkamp did  C48-89g)  and Katz,1980).  not demonstrate any  choice  trough  Aggression  avoidance between  c o n s i d e r a b l e t e r r i t o r i a l a c t i v i t y which may l a c k o f avoidance (Stevens e t . a l . , respond t o the symptoms do  symptoms  not  of  persist  S t a t i o n , Nanaimo, B.C.,  experiments  GBT  CD.F.  personal  Although f i s h may several  have  to  shown  128%  However,  seek  water  that  if  tanks  where  depth  F i f t e e n gram  the may  these  Biological  not  CVeitkamp,  CEbel  et.  is  Chinook  suffer 1976). water  at 130% i n a 9 m deep tank s u r v i v e d a t a much shallow  caused  fish  Pacific  a  communication).  chinook with a mean weight o f 19g, h e l d i n  those i n  fish  in  have r e s u l t e d i n  Alderdice,  seek depth i n a f o u r meter cage d i d up  steelhead  behaviour  the  1980). and  doubtful  not d e t e c t and a v o i d s u p e r s a t u r a t i o n ,  m o r t a l i t y i s g r e a t l y reduced.  saturations of  is  In an avoidance experiment, significant  study.  behaviour  allowed  to  mortalities  at  Vild  juvenile  supersaturated  higher  a l . , 1971).  available  rate  than  Observations  57 i n d i c a t e d t h a t most f i s h remained between about 1 and 4 m o f t h e surface. greater  Vertical  distribution  of  0.42g  maintained  I f depth  fully  dissolved  compensate  for  the  s u b s t a n t i a l m o r t a l i t i e s can occur A  decrease  in  o v e r i n f l a t i o n w i l l impose P o s i t i v e buoyancy w i l l swimming c o n t i n u o u s l y there  fish  sufficient  gas  density  fish  t o maintain  due  to  to  expend  on  pressure  water  the  more  p o s i t i o n i n the  well  swimbladder  energy  water to  systems  fish.  allow and  f i s h any o p p o r t u n i t y  t o compensate f o r t h e excess gas  Vild  with  hydroelectric  dams.  c o n s i d e r a b l e seasonal  gas  supersaturation  Dissolved  gas  full  stream  high (above 135%) i n s p r i n g and The  are  1969).  l i k e l y t o promote GBT.  subject  summer  downstream  when  large  release  to of  migration  water  with  and  volumes of  of  juvenile  spillage  Young f i s h most s e n s i t i v e t o  o v e r i n f l a t i o n often inhabit  with  when no water i s s p i l l e d ,  salmonids c o i n c i d e s with t h e peak times f o r water the dams CEbel,  pressures.  On t h e Columbia R i v e r , TGP i s near  e q u i l i b r i u m i n t h e f a l l and winter  spilled.  allow  associated  f l u c t u a t i o n s and vary with t h e  water over s p i l l w a y s o f dams.  are  levels  in  column,  a l t e r a t i o n s may c r e a t e s u p e r s a t u r a t i o n problems and do not  f i s h must cope  to  supersaturation  constraints  hydrostatic  Shallow ponds,  i s not  CEbel and Raymond, 1976).  energetic  force  i s inadequate  compensation.  water  a  depth a t h i g h e r s a t u r a t i o n l e v e l s than those a t the lower  l e v e l s CDawley et. a l . , 1976).  if  Chinook  over  swimbladder  supersaturation  levels  58 5.0  SUMMARY  Rainbow t r o u t h e l d  in  denied access t o t h e s u r f a c e pressure.  The  threshold  gas  show  supersaturated  an  dissolved  increase gas  in  pressure  o f 0.95.  Increase i n the ONR  AP f o r swimbladder  and  swimbladder differential  found t o cause i n f l a t i o n o f the swimbladder was 27 ONR  water  mmHg  r e s u l t e d i n a higher  for  an  threshold  inflation.  Movement o f gas i n t o the  swimbladder  is  passive  and  w i l l cause a r i s e i n p r e s s u r e u n t i l the d i f f u s i o n g r a d i e n t i s n i l or the gas i s e x p e l l e d out the pneumatic duct. DRP  i s r e l a t e d t o the s i z e o f t h e f i s h .  DRP v a l u e s and a r e s u b j e c t  to  the  The t h r e s h o l d f o r  Small f i s h  higher  have  degree  of  higher pressure  b u i l d u p w i t h i n the swimbladder.  expansion decrease  Corresponding  t o the excess swimbladder p r e s s u r e i s  o f swibladder  volume.  The volume change r e s u l t s  i n d e n s i t y and p o s t i v e buoyancy.  s m a l l f i s h , they experience  the  Once the DRP has been reached is  pressure  alleviate  decrease  The  density.  a  portion  of  subsequent  release  of  completely.  T h e r e f o r e , a f i s h h e l d i n s u p e r s a t u r a t e d water w i l l  continuously  a buoyant f o r c e . The l a r g e  i n c r e a s e depth and Although  positive  in  buoyancy  experience  not  released.  a  Due t o the high DRP o f  i n the swimbladder,  the swimbladder gas does  greatest  in  an  change  in  compensate  density for  the  causes  small  swimbladder  fish  to  expansion.  swimbladder i n f l a t i o n occurs f o r a l l s i z e s o f t r o u t h e l d  i n gas s u p e r s a t u r a t e d fish.  water, the impact  Therefore, f i s h t h a t experience  must compensate by seeking depth.  is  greatest  for  small  the g r e a t e s t buoyant f o r c e  60 6.0  LITERATURE CITED  A l d e r d i c e , D.F. and J.O.T. Jensen. 1985. Assessment o f the I n f l u e n c e o f gas s u p e r s a t u r a t i o n on salmonids i n the Nechako R i v e r i n r e l a t i o n t o Kemano completion. Canadian Technical Report o f F i s h e r i e s and A q u a t i c S c i e n c e No. 1386. Beiningen, K.T. and V.J. E b e l . 1970. E f f e c t o f John Day Dam on d i s s o l v e d n i t r o g e n c o n c e n t r a t i o n s and salmon i n the Columbia R i v e r , 1968. Trans. Am. F i s h . Soc. 99:664-671. Bouck, G.R. 1980. E t i o l o g y o f gas bubble d i s e a s e . F i s h . Soc. 109:703-707.  Trans. Amer.  Brawn, V.M. 1964. Some f u n c t i o n s o f the swimbladder ducts i n A t l a n t i c and Pacific herring. PhD. U n i v e r s i t y o f B r i t i s h Columbia. 256pp.  and i t s thesis,  Chamberlain, G.V. , V.H. N e i l l , P.A. Romanowsky and K. Strawn. 1980. Vertical responses o f A t l a n t i c croaker to gas s u p e r s a t u r a t i o n and temperature change. Trans. Amer. Fish. Soc. 109:737-750. C l a r k , M.J.R. 1977. Environmental p r o t e c t i o n dissolved gas study: Data summary 1977. Province of B r i t i s h Columbia, M i n i s t r y o f Environment, Report No. 77-10. C o l t , J.E. 1983. The computation and r e p o r t i n g o f d i s s o l v e d levels. V a t e r Res. 8:841-849. Cornachia, J.V. and J.E. C o l t . 1984. The e f f e c t s o f gas s u p e r s a t u r a t i o n on l a r v a l s t r i p e d bass, Morone (Valbaum). J . F i s h Diseases. 7:15-27.  gas  dissolved saxatilis  Dawley, E.M., M. Schiewe and B. Monk. 1976. Effects of long-term exposure to supersaturation of dissolved atmospheric gases on j u v e n i l e chinook salmon and s t e e l h e a d t r o u t i n deep and shallow t e s t tanks. p 1-10. In D.H. F i c k i e s e n and M.J. Schneider Ceds), Gas Bubble Disease: Proceedings o f a workshop h e l d at Richland, Washington, October 8-9, 1974. Energy Res. Dev. Admin., Oak Ridge, Tennessee, USA.  61 Dawley, E.M., and V.J. E b e l . 1975. Effects of c o n c e n t r a t i o n s o f d i s s o l v e d atmospheric gas on chinook salmon and s t e e l h e a d trout. Fishery 73(4):787-796.  various juvenile Bulletin  E b e l , V.J. 1969. Supersaturation of nitrogen i n t h e Columbia r i v e r and i t s e f f e c t on salmon and s t e e l h e a d t r o u t . Fishery B u l l e t i n 68(1):1-11. E b e l , W.J. and H.L. Raymond. 1976. E f f e c t o f atmospheric gas s u p e r s a t u r a t i o n on salmon and s t e e l h e a d t r o u t o f the Snake and Columbia R i v e r s . Marine F i s h e r i e s Review 38(7):1-14. Ebel,  V.J., E.M. Dawley and B.H. Monk. 1971. Thermal t o l e r a n c e o f j u v e n i l e P a c i f i c salmon and s t e e l h e a d t r o u t i n relation to supesaturation of nitrogen gas. Fishery Bulletin 69(4):833-843.  Fahlen, G. 1971. The f u n c t i o n a l morphology o f the o f the genus Salmo. Acta Anat. 78:161-184. Fahlen, G., B. F a l c k and E. Rosengren. 1965. the swimbladder o f Gadus c a l l arias and Salmo P h y s i o l . Scand. 64:119-126.  gas  bladder  Monoamines i n irideus. Acta  Fange, R. 1976. Gas exchange i n the swimbladder. In R e s p i r a t i o n o f amphibious v e r t e b r a t e s . Ed. Academic Press, London.  p 189-211. G.M. Hughes.  Fidler, L.E. 1985. A study o f the biophysical a s s o c i a t e d with gas bubble trauma in fish. MSc. U n i v e r s i t y o f B r i t i s h Columbia 114pp. F i d l e r , L.E. 1984. A study o f b i o p h y s i c a l phenoma with gas bubble trauma i n f i s h e s . Penny Applied L t d . , Penny, B.C. 132pp.  phenoma Thesis,  associated Sciences,  Harvey, H.H. 1975. Gas d i s e a s e i n f i s h e s - a review. p 450 485 In V. A. Adams ( e d ) , Chemistry and P h y s i c s o f Aqueous Gas Solutions. The E l e c t r o c h e m i c a l Society, Princeton, New J e r s e y , USA.  62 Harvey, H.H. salmon.  1963. P r e s s u r e i n the e a r l y h i s t o r y o f the PhD t h e s i s , U n i v e r s i t y o f B r i t i s h Columbia.  Sockeye 267pp.  Harvey, H.H. and C.R. Bothern. 1972. Compensatory swimming i n the kokanee and sockeye salmon Oncorhynchus nerka CValbaum). J. F i s h B i o l . 4:237-247. J a s i n s k i , A. 1963. The v a s c u l a r i z a t i o n o f the a i r b l a d d e r i n fishes. P a r t I. A i r b l a d d e r o f the bleak CCoregonus albulal and rainbow t r o u t CSalmo i r i d e u s Gibb.5, and the ductus pneumaticus o f the e e l <.Angui.Ha anguilla L.). Acta B i o l o g i c a C r a c o v i e n s i a , V o l . VI:2-31. Jensen, J.O.T. 1980. E f f e c t o f t o t a l gas p r e s s u r e , temperature, and t o t a l water hardness on s t e e l h e a d eggs and alevins In Northwest F i s h C u l t u r e Conference. Courtney, B.C. K n i t t e l , M.D., G.A. Chapman and P.R. Garton. 1980. Effects of hydrostatic pressure on steelhead survival in air-supersaturated water. Trans. Amer. Fish. Soc. 109:7SS-759. Krogh, A. 1919. The r a t e o f d i f f u s i o n o f gases through animal t i s s u e s , with some remarks on the c o e f f i c i e n t of invasion. J . P h y s i o l o g y 52:391-408. Lapennas and Schmidt-Nielsen. 1977. Swimbladder t o oxygen. J . Exp. B i o l o g y 67:175-196.  permeability  Lowndes, A.G. 1942. The displacement method o f weighing living a q u a t i c organisms. J . Mar. B i o l . Assoc. UK. 25:555-574. Lund, M. and T.G. Heggberget. 1985. Avoidance response o f two—year o l d rainbow t r o u t , Salmo gairdneri Richardson, t o a i r s u p e r s a t u r a t e d water: h y d r o s t a t i c compensation. J. F i s h Biol. 26:193-200. Marsh, M.C. and F.P. Gorham. 1905. The gas d i s e a s e Report o f the United States Bureau of C1904):343-376.  in fishes. Fisheries.  McCutcheon, F.H. 1966. Pressure s e n s i t i v i t y , reflexes, and buoyancy responses i n t e l e o s t s . Animal Behav. 14:204-217.  63 M o r r i s , S.M. and swim bladder T i s s u e Res.  J.T. A l b r i g h t . 1979. U l t r a s t r u c t u r e of o f the g o l d f i s h , Carassius aurat us. Cell 198:105-117.  Pauley, G. B. and R.E. Nakatani. 1967. Histopathology bubble" d i s e a s e i n salmon f i n g e r l i n g s . J. Fish. Canada 24:867-871.  of Res.  the and  "gas Bd.  R a n d a l l , D.J. and C. Daxboeck. 1984. Oxygen and carbon d i o x i d e t r a n s f e r a c r o s s f i s h g i l l s pp 263-314 In V.S. Hoar and D.J. R a n d a l l Ceds), F i s h Physiology, V o l . 10A. Academic Press, New York, USA. S h i r a t a , S. 1966. Experiments on nitrogen gas disease with rainbow t r o u t f r y . Bulletin of Freshwater Fisheries Research Laboratory CTokyo). 15C2>:197-211. Shrimpton, J.M. 1985. Response o f coho salmon COncorhynchus kisutchy t o d i f f e r e n t l e v e l s o f gas supersaturation. BSc T h e s i s , U n i v e r s i t y o f V i c t o r i a , B r i t i s h Columbia. 44pp. Sigma Resource C o n s u l t a n t s L t d . 1983. Water q u a l i t y c r i t e r i a f o r salmonid h a t c h e r i e s . Report t o Department o f F i s h e r i e s and Oceans, Vancouver, B.C. Steen, J.B. 1970. The swimbladder as a hydrostatic organ, p 413-443. In W.S. Hoar and D.J. Randall Ceds), Fish Physiology, V o l . 4. Academic Press, New York, USA. Stevens, D.G., A.V. Nebeker and R.J. Baker. 1980. Avoidance responses o f salmon and t r o u t t o a i r — s u p e r s a t u r a t e d water. Trans. Amer. F i s h . Soc. 109:751-754. Stroud, R.K., G.R. Bouck and A.V. Nebeker. 1975. Pathology o f acute and chronic exposure of salmonid fishes to supersaturated water. p 435—449 In W.A. Adams Ced) Chemistry and Physics o f Aqueous Gas Solutions. The E l e c t r o c h e m i c a l S o c i e t y , P r i n c e t o n , New Jersey, USA. Sundnes, G., T. Enns and in fishes lacking 35C3):671-676.  P.F. Scholander. rete mirabile.  1958. J.  Gas Exp.  secretion Biology  64 T a i l , J.S. 1936. N i t r o g e n and argon i n salmonoid Can. J . Z o o l . 34:38-62. USEPA. 1973. Q u a l i t y c r i t e r i a f o r water. o f Columbia, USA.  swimbladders.  Washington,  District  Weitkamp, D.E. 1976. D i s s o l v e d gas s u p e r s a t u r a t i o n : Live cage b i o a s s a y a t Rock I s l a n d Dam, Washington. In D.H. F i c k e i s e n and M.J. Schneider Ceds), Gas Bubble Disease: Proceedings o f a workshop h e l d a t R i c h l a n d , Washington, October 8-9, 1974, p 24-36. Energy Res. Dev. Admin., Oak Ridge, Tennessee, USA. Weitkamp, D.E. and M. Katz. 1980. supersaturation literature. 109:659-702.  A review of dissolved Trans. Amer. Fish.  Welty, J.R., C.E. Wicks and R.E. Wilson. o f momentum, heat, and mass t r a n s f e r . New York, USA 803pp. Westers, H. 1983. saturation. In Wisconsin, USA.  gas Soc.  1984. Fundamentals 3rd e d i t i o n . Wiley,  Experience i n Michigan with gas supei— Gas S u p e r s a t u r a t i o n Conference, Milwaukee,  Wittenberg, J.B. 1958. The s e c r e t i o n of swimbladder o f f i s h . J . Gen. P h y s i o l .  inert gas into 41C4):783-804.  the  Wright, P.B. and W.E. McLean. 1984. The e f f e c t s o f a e r a t i o n on the r e a r i n g o f summer Chinook f r y COncorhynchus tshauytschcD a t the Puntledge Hatchery. Dept. F i s h . Oceans, Vancouver, B.C. 47pp.  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0097852/manifest

Comment

Related Items