The effect of S.W. on the osmoregulatory processes of Rainbow trout was studied. Rainbow trout were monitered for various acid--ba.se and respiratory parameters during F.W. - S.W. transfer. Plasma Cl⁻, total CO₂ and HCO₃⁻ concentrations were measured, as well as blood pH, Pa0₂ and PC0₂- V02₂, VG, VCO₂, and VH⁺ were calculated from the measured parameters. During the exposure to S.W. for 3 hours none of the measured variables changed significently, indicating that the Rainbow trout is indeed euryhaline. It appears that unlike the goldfish the trout has a branchial Cl⁻/HCO₃⁻ exchange diffusion pump that is of small capacity, because changes in the external concentrations of CI⁻ and HCO₃⁻ did not affect internal levels of these ions. Raising external Cl⁻ levels would cause a lowering in plasma HCO₃⁻ if there was a Cl⁻/HCO₃⁻ exchange diffusion pump in the gills. A second group of experiments involved the use of Cl⁻ to measure Cl⁻ fluxes in the gills of intact trout. Injections of HCO₃⁻ into the fish did not stimulate Cl⁻ efflux, indicating that if there is a Cl⁻/HCO₃⁻ exchange diffusion pump, it is of small capacity. Gill carbonic anhydrase levels were measured in the gills of F.W. and S.W. trout, S.W. and F.W. coho, and goldfish. Goldfish have a high level as does the S.W. coho. Carbonic anhydrase catalyses the formation of HCO₃ from C02 for the Cl⁻/HCO₃⁻ pump, and is thus indicative of the importance of the pump in Cl⁻ and HCO₃⁻ fluxes.. The significance of the differences in the ionic pumps of trout, coho, and goldfish are discussed in relation to their life histories.
Trout having a flexible osmoregulatory system (being euryhaline) while the coho and goldfish are more specialised being essentially stenohaline. / Science, Faculty of / Zoology, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/18865 |
| Date | January 1974 |
| Creators | Milne, Robert Stephen |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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