THE OSMOREGULATORY METABOLISM OP THE STARRY FLOUNDER, PLATICHTHYS STELLATUS by CLEVELAND PENDLETON HICKMAN, JR. B.A., DePauw University, 1950 M.S., University of New Hampshire, 1953 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of Zoology We accept this thesis as conforming to the required standard. THE UNIVERSITY OF BRITISH COLUMBIA June, 1958 Faculty of Graduate Studies PROGRAMME OF THE FINAL ORAL EXAMINATION FOR THE DEGREE OF DOCTOR OF PHILOSOPHY of CLEVELAND PENDLETON HICKMAN JR. B.A. DePauw University, 1950 M.S. University of New Hampshire, 1953 IN ROOM 187A, BIOLOGICAL SCIENCES BUILDING MONDAY, JUNE 30, 1958 at 10:30 a.m. COMMITTEE IN CHARGE DEAN F. H. SOWARD, Chairman H. ADASKIN W. S. HOAR W. A. CLEMENS W. N. HOLMES I. McT. COWAN C. C. LINDSEY P. A. DEHNEL H. McLENNAN R. F. SCAGEL External Examiner: F. E. J. FRY University of Toronto THE OSMOREGULATORY METABOLISM OF THE STARRY FLOUNDER, PLATICHTYS STELLATUS ABSTRACT Energy demands for osmotic regulation and the possible osmoregulatory role of the thyroid gland were investigated in the euryhaline starry flounder, Platichthys stellatus. Using a melt• ing-point technique, it was established that flounder could regulate body fluid concentration independent of widely divergent environ• mental salinities. Small flounder experienced more rapid disturb• ances of body fluid concentration than large flounder after abrupt salinity alterations. The standard metabolic rate of flounder adapted to fresh water was consistently and significantly less than that of marine flounder. In supernormal salinities standard metabolic rate was significantly greater than in normal sea water. These findings agree with the theory that energy demands for active electrolyte transport are greater in sea water than fresh water. Thyroid activity was studied in flounder adapted to fresh water and salt water. Correlative with the higher metabolic rate of small flounder was the more rapid turnover and excretion of radioiodine and greater thyroid uptake of small than large flounder. Percentage uptake of radioiodine by the thyroid was shown to be an insensitive and inaccurate criterion for evaluating thyroid activity in different salinities because removal rates of radioiodine from the body and blood differed between fresh water and marine flounder.. Using thyroid clearance of radioiodine from the blood as a measure of activity, salt water flounder were shown to have much greater thyroid clearance rates and, hence, more active thy• roid glands than flounder adapted to fresh water. The greater activity of the thyroid of marine flounder correlates with greater oxygen demands in sea water and suggests a direct or adjunctive osmoregulatory role of the thyroid gland of fish. GRADUATE STUDIES Field of Study: Comparative Animal Physiology Environmental Physiology W. S. Hoar Comparative Physiology W. S. Hoar Other Studies: Biochemistry Biochemistry Staff Mammalian Physiology D. H. Copp and E. C. Black Marine Invertebrate Zoology.. D. L. Ray (Friday Harbor Laboratory) i ABSTRACT Energy demands for osmotic regulation and the possible osmoregulatory role of the thyroid gland were investigated in the euryhaline starry flounder, Platichthys stellatus. Using a melting-point technique, it was established that flounder could regulate adequately body fluid concentration independent of widely divergent environmental salinities. Small flounder experienced more rapid dis• turbances of body fluid concentration than large flounder after abrupt salinity alterations. The standard metabolic rate of flounder adapted to fresh water was consistently and significantly less than that of marine flounder. In supernormal salinities standard metabolic rate was significantly greater than in normal sea water. These findings agree with the theory that energy demands for active electrolyte transport are greater in sea water than fresh water. Thyroid activity was studied in flounder adapted to fresh water and salt water. Correlative with the higher metabolic rate of small flounder was the more rapid turnover and excretion of radioiodine and greater thyroid uptake of small than large flounder. Percentage uptake of radioiodine by the thyroid was shown to be an insensitive and inaccurate criterion for evaluating thyroid activity in different salinities because removal rates of radioiodine from the s body and blood differed between fresh water and marine flounder. Using thyroid clearance of radioiodine from the blood as a measure of activity, salt water flounder were shown to have much greater thyroid clearance rates and, hence, more active thyroid glands than flounder adapted to fresh water. The greater activity of the thyroid of marine flounder correlates with greater oxygen demands in sea water and suggests a direct or adjunctive osmoregulatory role of the thyroid gland of fish. In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representative. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia Vancouver 8, Canada. ii TABLE OP CONTENTS I INTRODUCTION A* Environmental relations of starry flounder, lemon sole and speckled sand dab • ••••eo«...o«eo.»......<>oo 3 Be Collection and care of fish ••o.eeo»<>.«» III THE OSMOTIC RESPONSE OF STARRY FLOUNDER TO CHANGES IN ENVIRONMENTAL SALINITY „.„».. 9 A. Determination of body fluid concentration »•••••••••• 10 1. Melting-point determination «..••.••••••••••••« 10 2© Experimental procedure M«M«»««««»»««t««tM«« 11 B. ReSUltS ..eo........•<,•••••»..«oo...o...........°..c. 13 1« Starry flounder in normal sea water 13 2. Starry flounder in hypotonic media: regulation against overhydration and salt depletion „„„ 17 a, concentration disturbances •»•••••••••»••• 17 b, volume disturbances ••»««i«««n«MMtMM 18 3. Starry flounder in supernormal hypertonic media: regulation against dehydration and salt excess 20 4* The effect of body size on alterations in body fluid osmolarity after abrupt changes in envir• onmental salinity ••<«•>••«««•<•••••«««« 20 C. Comment «••••<••»••••«•««•••••«<••»•••«•«••••<•(••«< 23 IV THE EFFECT OF ENVIRONMENTAL SALINITY ON THE OXYGEN CONSUMPTION OF FIATFISH 27 A. Determination of standard metabolic rate .........oe . 32 iii 1. Apparatus •••••<,«••••••« <>«••»•••••••••••••••••• 32 2, Chemical analysis o» 35 3.o Experimental procedure •<»«<«•<«•«•••«•<«••••» 35 4« Statistical procedures „„( „.,•«« 36 B. Results ............... o • 37 1» Standard metabolic rates of starry flounder, lemon sole and speckled sand dab •••••••••••••• 37 a. interspecific comparison ••••••••••••<,•••<, 37 b. significance of the slope of regression of metabolic rate ••••••.••••»•••*•« 40 2. Diurnal rhythm in the metabolic rate of Starry flounder ••oa«oo*ooo*«ooe««o«««*«*o*9eaa 43 3» Effect of starvation on the standard metabolic rate of starry flounder •••••»....•<>••<>••.0oa«* 48 4* Effect of salinity on the standard metabolic rate of starry flounder O»M.O 55 5« The effect of salinity on the standard metabolic rate of lemon sole and speckled sand dab 9»MM«.<»MM<ct«Mi»» 68 C. Comment •••.»««..*.«.o<>.....*«..e .....0 * »«• 72 V THE EFFECT OF ENVIRONMENTAL SALINITY ON THYROID ACTIVITY AND RADIOIODIDE METABOLISM OF THE STARRY FLOUNDER , 80 A, Methods: determination of iodide movement and thyroid activity with radioiodine •••••••••••••«••••• 86 1. Injections •«•««••••«•• •««•••••«• 86 2. Collection, treatment and counting of samples 87 a. thyroid 90 b. blood .,. 90 c. urine («<o«*Mi«ti««» gMi»««i«i • 91 d. body ............. 91 3. Expression of results e...•...•.•«•••<>•«•.••••c 92 B. Results .... o 95 1. Factors influencing the excretion of radioiodide 95 a. effect of radioisotope reentry ••••••••o.. 95 b. effect of salinity »•.••••...••• 97 c. relative importance of renal and extrarenal excretion of I 102 d. effect of size • •»...e.o««.e.o* 107 2. Factors influencing uptake of radioiodide by the thyroid gland •••• •«•«••• ... 107 a. effect of iodide content of the water «... 107 b. effect of salinity .........<>•. Ill I. the behavior of radioiodide in the blood 112 ii. the thyroidal clearance of radio• iodide from the blood 116 c. effect of body size on thyroid activity of starry flounder and speckled sand dab 118 VI DISCUSSION • » 123 VII SUMMARY AND CONCLUSIONS .. 134 APPENDIX 136 LITERATURE CITED 140 V LIST OF FIGURES" la Average melting points of serum and urine of Platicht stellatus transferred abruptly from sea water of 25 /oo to dilute sea water and fresh water ......<>».......o...*•••• 14 lb Average melting points of serum and urine of Platichthys stellatus transferred abruptly fgom sea water of 25 "/oo to concentrated sea water of 46 /oo ••••••••••••«•••••••«• 14 2 Melting-points of serum and urine of Platichthys stellatus transferred abruptly to concentrated sea water of 46 v/oo 21 3 The effect of body size on the rapidity of change ofsenum melting-point of PlatichthyB stellatus ...».<>•..•..<,•<> 22 4 A diagrammatic representation of fluid shifts attending concentration and volume disturbances of flounder transferred to fresh water. « 25 5 A view of part of the appartus for standard metabolism measurements