Interactions of Acute Temperature and pH Changes on Metabolic Rates and Hypoxia Tolerance: A Comparison Between Mid- and North-Atlantic Species

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NOAA Hollings Fellow Danielle with our skate respirometer

The increasing use of autonomous data recording devices has revealed temperature, pH, and dissolved oxygen are extremely variable in temperate coastal and estuarine areas over both tidal and seasonal time scales. We hypothesized species inhabiting these areas likely possess species-specific physiological mechanisms which will allow them to withstand the environmental changes predicted under climate change. To test this hypothesis, we used intermittent-flow respirometry to measure changes in metabolism (e.g., aerobic scope, standard metabolic rate) and hypoxia tolerance across multiple temperature and pH levels in clearnose skate (Raja eglanteria), summer flounder (Paralichthys dentatus), and thorny skate (Amblyraja radiata). Our preliminary results suggest the two estuarine species native to the mid-Atlantic Bight (clearnose skate and summer flounder) are more tolerant of acute thermal stress than thorny skate (a species with a more northern and less environmentally-variable distribution). However, all three species exhibited an antagonistic, interactive effect of reductions in pH and increases in temperature on hypoxia tolerance. The differential responses to acute changes in temperature and pH conditions may have management implications under climate change, especially for the skates which are currently managed as a species complex.