Graduation Date

Spring 2024

Document Type



Master of Science degree with a major in Biology

Committee Chair Name

Dr. Paul Bourdeau

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. Catalina Cuellar-Gempeler

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Dr. Emily Jones

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Dr. Erik Jules


Predator-prey, Risk cues, Marine ecology, Pisaster-Tegula interaction

Subject Categories



Chemical cues emanating from predators can play a key role in aquatic predator-prey interactions and food webs. Understanding how prey respond to these risk cues is therefore critical for understanding the direct effects of predators on prey populations and their indirect effects on communities. To respond adaptively, prey must accurately assess the risk of predation associated with perceived chemical cues, an oft-documented phenomenon. However, little is known about how cues disperse, persist, and degrade, all of which could limit the adaptive responses of prey. Using laboratory-based observations of a well-studied predator cue-induced antipredator behavior by the marine gastropod Tegula funebralis in response to the predatory sea star Pisaster ochraceous, I found that Pisaster risk cue (as measured by Tegula’s behavioral response), decreases rapidly, with responses reduced by >50% within 24h. In conjunction with the findings of further experimentation, this suggests that microbial activity contributes to cue degradation. Further, cue activity was preserved by freezing cue water for up to 72h, which presumably slowed microbial degradation. Surprisingly, it appeared that microbes themselves may be a key component of Pisaster risk cue, as Tegula did not respond to cue water that was filtered to remove microbes. Moreover, when Pisaster cue was treated with the antimicrobial tetracycline, I saw a significant effect on Tegula’s antipredator behavioral response. Taken together, my results suggest that microbial activity is directly responsible for mediating how prey perceive predator cues, and assess predation risk, in the ecologically important Tegula-Pisaster interaction.

Citation Style



Thesis/Project Location


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