In partial fulfillment of the requirements for the degree of

Doctor of Philosophy in Biology

In the

School of Biological Sciences

Alex Draper

Will defend his dissertation

Impacts of Climate Change on Physiology, Behavior, and Predator-Prey Interactions

in Oyster Reef Communities

Tuesday, April 12th, 2022

12:00 PM

Ford ES&T Room L1118

https://bluejeans.com/278656578/0421

 Thesis Advisor:

Marc Weissburg, Ph.D.

School of Biological Sciences

Georgia Institute of Technology

Committee Members:

Mark Hay, Ph.D.

School of Biological Sciences

Georgia Institute of Technology

Julia Kubanek, Ph.D.

School of Biological Sciences

School of Chemistry and Biochemistry

Georgia Institute of Technology

Emily Weigel, Ph.D.

School of Biological Sciences

Georgia Institute of Technology

Dave Hudson, Ph.D.

Remote Ecologist, Inc.

The Maritime Aquarium at Norwalk

ABSTRACT: Predators exert powerful influences on community structure through direct consumption and indirect predation risk that cascade down to lower trophic levels. However, these effects are shifting in marine ecosystems due to global warming and ocean acidification, so predicting community responses to climate change requires examining the physiological and behavioral mechanisms that drive changes in predator-prey interactions. In this dissertation, I developed a framework for understanding how warming and acidification can alter predator-prey interactions in oyster reefs by investigating the physiological and sensory-mediated behavioral responses of blue crab predators (Callinectes sapidus) and mud crab prey (Panopeus herbstii). First, I compared the physiological responses of blue crabs and mud crabs to warming and acidification. While survival of both species was negatively affected by the combination of these stressors, differences in metabolic responses suggest that mud crabs and blue crabs are differentially adapted to local environmental conditions that influence their responses to climate change. Next, I focused on the effects of warming and acidification on the chemosensory foraging behaviors of blue crab predators to attractive food cues using a two-channel choice flume. I found that warming slightly changed kinematic responses of blue crabs to prey cues, but overall their chemosensory function is robust to climate change. Finally, I investigated the effects of these stressors on the transmission and detection of blue crab predator cues that consequently suppress foraging behavior in mud crab prey, using either predator cues stressed in acidified conditions or prey stressed in warmed and acidified conditions. Warming constrained overall foraging activity of mud crabs regardless of predator cue, but acidifying the cue or the mud crabs did not affect this antipredator response. Thus, warming may have stronger effects than acidification on community dynamics in oyster reefs by compromising consumptive effects of predator control, shifting to emphasize non-consumptive effects as sensory function in this system remains robust to acidification. Overall, these findings highlight the significance of understanding climate change effects on physiology, behavior, and species interactions in marine systems in order to better predict the ecological consequences of anthropogenic change on community structure and function.