Oxygen consumption rate during recovery from loss of equilibrium induced by warming, hypoxia, or exhaustive exercise in rainbow darter (Etheostoma caeruleum).

Animals routinely encounter environmental (e.g., high temperatures and hypoxia) as well as physiological perturbations (e.

Impact of turbidity on the gill morphology and hypoxia tolerance of eastern sand darter (Ammocrypta pellucida).

Anthropogenic stressors such as agriculture and urbanization can increase river turbidity, which can negatively impact fish gill morphology and growth due to reduced oxygen in the benthic environment. We assessed the gill morphology, field metabolic rate (FMR), and two hypoxia tolerance metrics (oxygen partial pressure at loss of equilibrium, PO at LOE, and critical oxygen tension, P) of eastern sand darter (Ammocrypta pellucida), a small benthic fish listed as threatened under the Species at Risk Act in Canada, from rivers in southern Ontario. Field trials were conducted streamside in the Grand River (August 2019; mean NTU 8) and in the comparatively more turbid Thames River (August 2020; mean NTU 94) to test the effect of turbidity on each physiological endpoint.

Impacts of temperature and turbidity on the gill physiology of darter species.

Fish gills are complex organs that have direct contact with the environment and perform numerous functions including gas exchange and ion regulation. Determining if gill morphometry can change under different environmental conditions to maintain and/or improve gas exchange and ion regulation is important for understanding if gill plasticity can improve survival with increasing environmental change. We assessed gill morphology (gas exchange and ion regulation metrics), hematocrit and gill Na/K ATPase activity of wild-captured blackside darter (Percina maculata), greenside darter (Etheostoma blennioides), and johnny darter (Etheostoma nigrum) at two temperatures (10 and 25 °C) and turbidity levels (8 and 94 NTU).

Physiological differences between wild and captive animals: a century-old dilemma.

Laboratory-based research dominates the fields of comparative physiology and biomechanics. The power of lab work has long been recognized by experimental biologists. For example, in 1932, Georgy Gause published an influential paper in Journal of Experimental Biology describing a series of clever lab experiments that provided the first empirical test of competitive exclusion theory, laying the foundation for a field that remains active today.

Seasonal and environmental effects on upper thermal limits of eastern sand darter ().

Anthropogenic stressors are predicted to increase water temperature, which can influence physiological, individual, and population processes in fishes. We assessed the critical thermal maximum (CT) of eastern sand darter (), a small benthic fish listed as threatened under the in Canada. Field trials were conducted stream side June-November 2019 in the Grand River, Ontario, to encompass a range of ambient water temperatures (7-25°C) for which agitation temperature (T) and CT were determined.