2023 128 ENV

Turbulent Tidepool Temperature and Porcelain Crab Fitness: What's the Connection?

By: Joe Holdreith, Alexis Hopper

Department: Biology

Faculty Advisor: Dr. Jonathon Stillman

Climate change is rapidly pushing average temperatures beyond the limits many organisms can tolerate. Some ectotherms are adapted to wide temperature ranges and can tolerate dramatic temperature changes. Others, even of the same species or population, cannot. Intertidal crabs tend to experience temperature fluctuations as they experience transitions between high and low tides, which allows them to cope with variations in temperature. It remains unknown which thermal conditions yield the highest thermal tolerances. I hypothesize that crabs living in the most turbulent temperature ranges of the intertidal zone will have the greatest thermal tolerance. I will collect embryos from crabs from the upper and lower zones and subject them to heat shock in a lab setting. Heat shock will be administered with a hot water bath where embryos are held in a custom steel block and bathed at a constant temperature near the thermal maximum of the field site they were collected from. I will then measure energetics via respirometry, survival, time to hatching, and yolk volume via microscopy. I expect that embryos from the lower intertidal zone, the most thermally heterogeneous zone, will see the lowest deviation in energetics, highest survival, fastest development and yolk consumption, and most rapid time to hatching. Determining which thermal conditions yield the highest thermal tolerances will inform our understanding of which species and populations are most susceptible to climate change.