Biochemical Ecology on Coral Reefs

Mark Hahn and Kristen Whalen, Biology Department, WHOI
Christopher Reddy, Marine Chemistry and Geochemistry Department, WHOI

In marine communities, predation plays a pivotal role in affecting the phenotype of organisms as well as their abundance and distribution. This is especially true on coral reefs, where consumers exert strong selective pressure on prey to avoid being eaten. Prey species unable to physically escape consumers often produce noxious compounds, termed allelochemicals, as a mechanism of defense against predation. However, some specialized consumers have evolved protective mechanisms that allow them to cope with chemically defended prey. We hypothesize that the ability of marine consumers to tolerate dietary allelochemicals may involve biochemical resistance mechanisms that facilitate xenobiotic detoxification, excretion or sequestration.

This proposal focuses on biochemical resistance mechanisms involving multixenobiotic transporter proteins. Currently, little is known about the role of multixenobiotic transporters in marine invertebrates that feed on allelochemical-rich prey. The objectives of this research are 1) to characterize the diversity and dietary regulation of multixenobiotic transporters in generalist (the gastropod Cyphoma gibbosum) and specialist (the nudibranch Tritonia hamnerorum) molluscan predators that feed on chemically defended gorgonian corals, and 2) to test the hypothesis that gorgonian extracts contain substrates for these transport proteins. We will test the hypothesis that the diversity and selectivity of multixenobiotic transporters is related to feeding specialization. We will also investigate the potential participation of these transporters in the sequestration of dietary metabolites in specialist molluscan predators. This collaborative effort between a molecular toxicologist, a chemist, and an ecologist will help elucidate mechanisms of allelochemical resistance in these molluscs and provide a molecular understanding of patterns of predation and herbivory on coral reefs.