Term of Award

Spring 2008

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

Daniel F. Gleason

Committee Member 1

Bruce A. Schulte

Committee Member 2

Risa A. Cohen

Abstract

Sessile organisms employing inducible defenses may receive protection from consumers while simultaneously minimizing the metabolic costs of maintaining these defenses. To investigate if reef sponges in the South Atlantic Bight employ inducible chemical defenses, I tested two predictions with Ircinia campana, I. felix, and Aplysina fulva. First, concentrations of antipredator compounds should covary with the abundance of sponge predators. Second, higher compound concentrations should be more effective at deterring predators. Secondary metabolite concentrations in two (I. campana and I. felix) of the sponge species showed temporal variation, which is consistent with the inducible defense hypothesis. Interestingly, higher concentrations of these compounds did not deter feeding by fish or urchins. In contrast, A. fulva, showed no significant temporal variation in the concentration of secondary metabolites, but had deterrent effects on fish predators even at low concentrations. Combined, these results do not support an antipredator strategy based on inducible chemical defenses.

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