The effect of acclimation temperature on hypoxia tolerance of mummichog killifish (Fundulus heteroclitus)
| dc.contributor.advisor | Scott, Graham | |
| dc.contributor.author | Ridgway, Megan | |
| dc.contributor.department | Biology | en_US |
| dc.date.accessioned | 2023-02-27T20:09:54Z | |
| dc.date.available | 2023-02-27T20:09:54Z | |
| dc.date.issued | 2023 | |
| dc.description.abstract | Climate change is leading to rapid change in aquatic environments, increasing the mean and variability of temperatures, and increasing the incidence of hypoxia. We investigated how acclimation to constant temperatures or to diel temperature fluctuations affect hypoxia tolerance in mummichog killifish (Fundulus heteroclitus). Killifish were acclimated to constant cool (15˚C), constant warm (25˚C), or a diel temperature cycle (15˚C at night, 25˚C during day) for 6 weeks. I then measured hypoxia tolerance (time to loss of equilibrium in severe hypoxia, tLOE; critical O2 tension, Pcrit), whole-animal metabolism, gill morphology, haematology, and tissue metabolites at 15˚C and 25˚C in a full factorial design. Among constant temperature groups, tLOE was highest and Pcrit was lowest in fish tested at their acclimation temperature. Warm acclimated fish had lower metabolic rate at 25˚C and greater gill surface area (less coverage of lamellae by interlamellar cell mass, ILCM), but cool acclimated fish had greater brain glycogen stores. Therefore, effects of constant temperature acclimation on hypoxia tolerance were temperature specific and not exhibited broadly across test temperatures, and they were associated with different underlying mechanisms. Hypoxia tolerance was less sensitive to test temperature in fish acclimated to fluctuating temperatures compared to fish acclimated to constant temperature. Acclimation to fluctuating temperatures also increased haemoglobin-O2 affinity of the blood (decreased P50) compared to constant temperature groups. Therefore, acclimation to fluctuating temperatures helps maintain hypoxia tolerance across a broader range of temperatures, and leads to some distinct physiological adjustments that are not exhibited by fish acclimated to constant temperatures. | en_US |
| dc.description.degree | Master of Science (MSc) | en_US |
| dc.description.degreetype | Thesis | en_US |
| dc.description.layabstract | Human disturbance is leading to increased variability of environmental temperature as well as increased incidence and severity of aquatic hypoxia (low oxygen conditions). The effect of elevated temperatures on hypoxia tolerance is well studied, however little is known about how environmentally relevant temperature variability impacts hypoxia tolerance in fish. To address this research gap, I examined the effects of constant temperature and fluctuating temperature regimes on the hypoxia tolerance of mummichog killifish. I provide evidence that acclimation temperature impacts hypoxia tolerance, gill structure, haematology and energy stores in the brain. My thesis demonstrates that thermal history can alter temperature-sensitive physiological traits that fish use to cope with stressors such as low oxygen. These findings contribute to the existing body of work that documents the interactive effects of combined stressors in changing ecosystems on the physiology of fish. | en_US |
| dc.identifier.uri | http://hdl.handle.net/11375/28345 | |
| dc.language.iso | en | en_US |
| dc.subject | O2 transport; anaerobic metabolism; gill remodelling; respiration; teleost; thermal breadth | en_US |
| dc.title | The effect of acclimation temperature on hypoxia tolerance of mummichog killifish (Fundulus heteroclitus) | en_US |
| dc.type | Thesis | en_US |