Thermal Tolerance of Common Snook by Latitude and Salinity
Applied Research
Brittany Scharf
Marine Agent
UF/IFAS Extension
Brooksville
Abstract
Abiotic factors such as temperature and salinity can affect fish physiological and behavioral responses, resulting in environmentally induced variation in thermal tolerance. Such variation in ecological conditions may therefore influence species distributions across geographic ranges and habitat types. Local adaptations may account for differences in thermal tolerance to allow fish to survive in thermal refuges and thus persist in regions where environmental conditions may be otherwise unsuitable. For example, euryhaline fishes may occupy waters of salinity near 12 ppt to be isotonic with their environment, maximizing energy available for growth and survival. The Common Snook Centropomus undecimalis is one of Florida's most popular sport fish. It occupies various coastal habitats spanning from artificial reefs to freshwater rivers where they are exposed to fluctuating temperatures and salinities. We ran chronic lower-lethal temperature experiments on juvenile Common Snook (239 - 377 mm total length) for three salinity treatments (3 ppt, 15 ppt, and 30 ppt) to better understand how salinity affects survival and ultimately the availability of thermal refuge habitat. Cessation of feeding, loss of equilibrium, and death were recorded. Unexpectedly, our finding showed that this species is the least cold-tolerant (10.49°C) at the mid-salinity treatment (15 ppt). Lower-lethal temperature (9.17°C) for the high-salinity treatment (30 ppt) was similar to previous studies; however, our lower-lethal temperature (9.21°C) for the low-salinity treatment (3 ppt) was much lower than published findings and suggests potential habitat and thermal refuge characteristics during cool winter periods. Furthermore, our latitudinal findings support that this species range expansion has occurred due to mild winters and the development of an overwintering behavior type. We plan to further investigate lower-lethal temperatures for this species at the northern limit of their range.
Poster has NOT been presented at any previous NACAA AM/PIC
This poster is being submitted for judging. It will be displayed at the AM/PIC if not selected as a State winner. The abstract will be published in the proceedings.
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Authors: Brittany Scharf
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Scharf, B. Marine Agent, University of Florida, Florida, 34604