Open Collections

Staples, Ben

University of British Columbia

The factors limiting the poleward range limits of aquatic ectotherms remain poorly understood, although it is likely that these range limits may be dependent on the ability of a species to tolerate low temperatures during the winter. Understanding these factors is important because anthropogenic climate change may lead to movements of species distributions poleward as they track their thermal niche. However, most lab studies to evaluate the ability of species to cope with climate change use relatively short acclimation periods, which may not be appropriate given the length of winter periods at high latitudes. Here, I evaluate the effect of long-term thermal acclimation to a range of ecologically relevant temperatures in a southern subspecies of the Atlantic Killifish (Fundulus heteroclitus heteroclitus), which has a northern range limit where temperatures may drop below 10 ℃ for up to 6 months. After 3 months of thermal acclimation to 10 °C, 20 °C and 30 °C, swim performance as measured by Usprint declined in the cold-acclimated fish. Usprint declined further after 6 months of thermal acclimation, which was associated with the development of a dormancy-like behavioural change. However, despite reduced growth in length, the cold-acclimated fish consistently gained weight, resulting in increased body condition in these fish. Several cold-acclimated fish were noted to have eggs, two of which were fully gravid, suggesting Atlantic Killifish invest in reproduction in mild cold conditions. Liver glycogen content did not change between the acclimation groups. At the end of the acclimation period, gene expression in the muscle and liver was assessed, showing a varied response in metabolism-related genes. Upregulation of several cold-responsive genes was noted in both tissues. Overall, southern Atlantic killifish were unable to fully compensate swimming performance in the cold, but there was little other evidence that the duration of mild cold exposure limits the northern distribution of southern Atlantic Killifish.

Text

2024-06-20

Attribution 4.0 International

http://hdl.handle.net/2429/88491

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by/4.0/