This thesis deals with the importance of salinity to the distribution of three chironomid species of the genus Chironomus (C. anthracinus. C. athalassicus. and C. tentans). Research to date suggests that salinity and coexistence problems are the major factors influencing the distribution of the chironomid fauna of fresh and saline lakes in the Cariboo and Chilcotin areas of central British Columbia. The difference in the distribution of these three Chironomus species is particularly interesting. The investigation of the importance of salinity to their distribution consisted of a study of (i) the salinity tolerance of each species, (ii)the regulation of the haemolymph, and (iii) the influx and efflux of sodium and chloride ions. Several conclusions were drawn from the investigation. A difference in the salinity tolerance of each species was found in the laboratory: C. anthracinus and C. tentans did not survive at lake water conductivities above 9000 micro-o mhos/cm at 25 C, C. athalassicus survived in lake water conductivities at least as high as 15»000 micromhos/cm at o 25 C. Temperature affected the survival of each species in a similar way; at high temperatures survival time decreased. Sodium, potassium, and chloride as well as the concentration of the haemolymph were regulated by the three species at low salinities. C. athalassicus was the only species able to conform at higher external concentrations. C. athalassicus had a low sodium affinity and a powerful sodium uptake system compared to the other species. Chloride affinity and the power of the uptake system exceeded that of C. anthracinus and C. tentans. The general conclusion reached was that salinity does affect the distribution of the three Chlronomus species. More research is called for in this and related areas in order to more fully understand the distribution of the chironomid fauna. / Science, Faculty of / Zoology, Department of / Graduate

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

No description available.

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

Leung Ling Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 117-138). / Abstracts in English and Chinese. / Abstract (English) --- p.ii / Abstract (Chinese) --- p.iv / Acknowledgements --- p.vi / List of Abbreviation --- p.vii / List of Figures and Tables --- p.viii / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter Chapter 2 --- The effect of salinity on pentose phosphate pathway activity and red blood cells resistance to oxidative stress in silver seabream (Sparus sarba) --- p.4 / Abstract --- p.7 / Chapter 2.1 --- Literature review --- p.8 / Chapter 2.2 --- Materials and Methods --- p.17 / Chapter 2.3 --- Results --- p.32 / Chapter 2.4 --- Discussion --- p.54 / Chapter 2.5 --- Conclusion --- p.63 / Chapter Chapter 3 --- The effect of dietary carbohydrate level on pentose phosphate pathway activity and red blood cells resistance to oxidative stress in of silver seabream (Sparus sarba) --- p.65 / Abstract --- p.67 / Chapter 3.1 --- Literature review --- p.68 / Chapter 3.2 --- Materials and Methods --- p.77 / Chapter 3.3 --- Results --- p.80 / Chapter 3.4 --- Discussion --- p.101 / Chapter 3.5 --- Conclusion --- p.112 / Chapter Chapter 4 --- Summary --- p.113 / References --- p.117

The present study provided information for the role of the RAS in seabream osmoregulatory responses. The structure of angiotensinogen suggested that flounder type Ang II was the prevalent form in seabream. However, HPLC analysis suggested that different forms of angiotensins were present in seabream adapted to different salinities. The status of RAS was revealed in seabream adapted to different salinities and a higher status was found in hypersaline environment. Local renal RAS was identified and it may be activated in hyposmotic media and associated with an increase in glomerular and tubular function to excrete excess water. In general, the RAS in seabream displays differential status, both at systemic and local levels, which modulates osmoregulatory functions under acute and chronic salinity perturbation. / The renin angiotensin system (RAS) is involved in the control of body fluid homeostasis in silver seabream. Seabream angiotensinogen was cloned and sequenced in the present study. The sequence alignment showed that the angiotensinogen of seabream is most similar to that of pufferfish. Differential status of RAS was found among different salinities, with relatively higher RAS activity among hyperosmotic adapted seabream. Circulating angiotensin II (Ang II) was higher in hyperosmotic adapted seabream, with the highest value observed in seabream adapted to double-strength seawater. Although the level of immunoreactive angiotensins in freshwater adapted seabream was higher than that of brackish-water, Ang III, but not Ang II, was the prevalent circulating form in freshwater adapted seabream according to HPLC analysis. Hepatic angiotensinogen expression, however, did not show any statistical difference among different salinities. A positive feedback control for angiotensinogen by Ang II is present in the hepatic tissue of seabream as Ang II increased the expression of angiotensinogen in isolated hepatocyte but captopril lowered the angiotensinogen expression in intact fish. Branchial Na-K-ATPase activities were elevated by Ang II and the activities among different salinities showed a pattern similar to that of circulating angiotensins. However, upon abrupt hyposmotic transfer, branchial Na-K-ATPase elevated along with a decrease in circulating Ang II, an observation implying that the relationship between Na-K-ATPase and Ang II may only be causal. Captopril blockade not only lowered not only circulating Ang II levels but also that of cortisol, indicating RAS activity may limit cortisol secretion. An elevation in the circulating cortisol may be related to the increase in branchial Na-K-ATPase activities after abrupt hyposmotic transfer. The stimulatory effect on branchial Na-K-ATPase activity and the vasopressor effect of Ang II were more potent in hyposmotic than hyperosmotic adapted seabream, which indicates hyposmotic adapted seabream is more sensitive to RAS activation. The renal RAS in silver seabream functions independently from the systemic RAS as the pattern of renal angiotensins was dissimilar to that of systemic angiotensins. The renal RAS was activated in brackish water conditions and abrupt hyposmotic transfer significantly increased renal RAS activities. Kidney morphometrics also indicated that hyposmotic adaptation increase the filtering capacity of seabream nephrons. The number and diameter of glomeruli increase significantly in freshwater adapted seabream, which may vastly increase the filtering surface of the nephrons. Collecting tubules were more prevalent in the kidney of hyposmotic adapted seabream, with higher number, diameter and thickness, suggesting a lower water permeability of collecting tubules is essential for the formation of copious and diluted urine in hyposmotic environment. / Wong Kwok Shing. / "December 2005." / Adviser: Norman Y. S. Woo. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6144. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 130-145). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

No description available.

viii, 88 leaves : ill. ; 29 cm Notes Typescript (Another copy on microfilm is located in Archives) Thesis (M.A.)--University of Oregon Includes vita Bibliography: leaves 83-88

The locomotor responses of juvenile and adult sockeye salmon (Oncorhynchus nerka) to concurrent changes in temperature and salinity were examined in a controlled laboratory setting. I hoped to better understand how these environmental factors influence the coastal movements of migrating salmon. Juvenile sockeye were captured during the downstream migration from Great Central Lake on Vancouver Island, British Columbia, Canada. The fish were acclimated for 1 wk at 10°C, 20 ppt, and then tested in annular activity tanks. Spontaneous locomotor movements were recorded during concomitant changes in temperature and salinity using infra-red photometry. Raising the water temperature by 4°C in 1 h caused a dramatic increase in locomotor activity. Decreasing temperature by 4°C or varying salinity by 10 ppt from the control levels did not influence routine swimming speed and there was no interaction between factors. Adult sockeye homing to the Fraser River, British Columbia, Canada were captured along the nearshore migration route in two oceanographically distinct regions. Three groups of fish were collected from the cold, saline waters of Queen Charlotte Strait, near the northern end of Vancouver Island. Two groups of sockeye were captured within 60 km of the Fraser River in the warmer, less saline waters of the Strait of Georgia. The adults were acclimated 2-5 days at 12°C, 30 ppt and locomotor activity was tested in annular activity tanks. Routine swimming speed and turning rate rose when the water temperature was raised by 4°C in 2 h, however, locomotor activity was not influenced by decreasing temperature. In addition, decreasing salinity by 10 ppt in 2 h had no effect on swimming activity of adult sockeye and there was no interaction between the two factors. Fish taken from the Strait of Georgia generally showed a less dramatic response to increasing temperature than adults captured in Queen Charlotte Strait. Results indicate that warm coastal temperatures may influence the nearshore migration of both juvenile and adult sockeye salmon. / Science, Faculty of / Zoology, Department of / Graduate

A study was conducted to determine the effects of incubation salinity and temperature . and post-hatching temperature on salinity tolerance of Pacific herring (Clupea pallasi Valenciennes) larvae. Calorimetry experiments were also conducted on herring larvae that were incubated and reared in various combinations of salinity and temperature. In the salinity tolerance test, herring eggs were artificially fertilized in three salinities (13, 21 and 29°/ooS) at 6°C. Newly fertilized eggs were incubated in the same salinities as those in which they were fertilized at two levels of incubation temperature (6 and 12°C), making six incubation groups. During the peak of the hatching period, groups of larvae from each incubation group were exposed to a series of test salinities, ranging from 20 to 55°/ooS at three levels of post-hatching temperatures (6, 9 and 12°C). Salinity tolerance was measured by determining the mortality of larvae occurring in each test salinity over a period of 72 hours. Two approaches were employed: 1) time-mortality, and 2) dosage-mortality. The former provided estimates of the effective time to 50% mortality (ET₅₀), the latter, the effective dosage (salinity) to 50% mortality (ED₅₀). The ET₅₀ or ED₅₀ values were used as bases for comparison of the responses of larvae to incubation temperature and salinity, and post-hatching temperature. The results indicate that both incubation salinity and temperature exert a significant influence on the salinity tolerance of larvae. Eggs incubated in the highest salinity (29°/ooS) and lower temperature (6°C) produced larvae most tolerant to higher post-hatching salinities. Post-hatching temperature also showed a possible influence, although the trends seen were not statistically significant. Salinity tolerance of larvae hatching from the 6°C incubation temperature appeared to be maximized at post-hatching temperatures between 6 and 9°C; whereas, those larvae from the 12°C incubation temperature showed maximum salinity tolerance at 9 to 12°C post-hatching temperatures. The response. of. larvae to salinity may be a result of an irreversible non-genetic adaptation of the embryo to salinity and temperature during incubation. In the calorimetry experiments, samples of herring larvae were combusted in a microbomb calorimeter to determine caloric values. These larvae were hatched and reared in the same six combinations of incubation salinities and temperatures as those used in the main experiment. Larvae were sampled at day 0 (peak of hatching), 3, 6 and 9. Standard lengths, dry weights, ash-free dry weights and ash content of the larval samples were also taken. There was a considerable variability in the data for calorimetry of the herring larva. In general, larvae from all treatments, at hatching, averaged 6,586 cal/g ash-free dry weight and had a mean ash value of 8.25%, obtained by direct ashing. Mean standard length of larvae at the peak of hatching (day 0) ranged from 7.67 mm (12°C, 29°/ooS) to 9.93 mm (6°C, 13°/ooS). There was a trend towards larger larvae (greater standard length) at lower temperatures in lower salinities in all ages tested. Data on dry weights show a linear decrease in larval (body and yolk) weight from day 0 to day 9. Mean dry weight of larva at the peak of hatching ranged from 0.142 mg (6°C, 13°/OOS) to 0.162 mg (12°C, 21°/ooS; 12°C, 29°/ooS). At day 0, the largest larvae (in terms of dry weight) were found at higher temperatures in higher salinities, while at day 9 (past yolk-sac stage), the largest larvae were found at lower temperatures in lower salinities. The same trend was observed in terms of ash-free dry weight. / Science, Faculty of / Zoology, Department of / Graduate