Linking thermal tolerances to estuarine residency of NC fish species

Changing ocean temperatures due to climate change is expected to cause population shifts of NC fish species, thereby affecting marine ecosystems and fisheries. Gag grouper (Mycteroperca microlepis), gray snapper (Lutjanus griseus), mutton snapper (Lutjanus analis), lane snapper (Lutjanus synagris), black sea bass (Centropristis striata), sheepshead (Archosargus probatocephalus), planehead filefish (Stephanolepis hispidus), and pinfish (Lagodon rhomboides) are all fishes common to NC estuaries. For this ongoing experiment, we measured these species’ critical thermal maximum (CTMax) and critical thermal minimum (CTMin). Understanding their thermal limitations will allow us to predict where their populations may or may not move to, thus allowing us to provide advice for fishers and fisheries managers. We aimed to validate the climate variability hypothesis, which states that fishes that have evolved in more stable, or warmer, environments should be observed with a narrower temperature range. We hypothesized CTMax and CTMin will be dependent on fish size, that fish belonging in the same family will have similar temperature tolerances, that acclimation temperature will influence CTMax and CTMin, that CTMax and CTMin values will align closely with observed minimum and maximum estuarine temperatures, and that as estuaries warm, community structures will change. After experimentation, there was no significant relationship between fish size and temperature limits, and there were significant differences with temperature limits between families. Focusing on the Serranid family for the climate variability hypothesis, gag grouper, a more southerly species, were observed with a 3° C smaller temperature range compared to the black sea bass, thereby supporting the hypothesis. With the data received and conclusions reached from experimentation, it is important to understand how long each species is able to stay within the estuaries before the water temperatures reach their CTMax or CTMin values. Using water surface temperatures taken from two buoys in NC, we were able to measure the amount of days each species was able to stay each year. Changing water temperatures in NC estuaries will alter community composition, and in turn, allow different species to stay for longer, or sometimes shorter, periods of time. Understanding these temporal limitations will allow us to recognize the effects from ecosystem imbalances within the estuaries, such as a trophic cascade, as estuarine residencies change.Bachelor of Scienc