PECASE: Chemical Communication in Marine Ecosystems: Interactions Involving Harmful Algae and Zooplankton

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

Proposal Title: PECASE: Chemical communication in marine ecosystems: Interactions involving harmful algae and zooplankton Institution: Georgia Tech Research Corporation - GA Institute of Technology Most organisms use chemical signals to assess their environment and to communicate with other organisms. Chemical cues for the purposes of defense, mate attraction, habitat selection, and food tracking are known to be crucial, widespread, and diverse. As our understanding of receptor-ligand interactions, biosynthetic pathways, sensory biology, hydrodynamics, and ecosystem function has improved dramatically in the last decade, the opportunity to address the chemistry of marine biological processes has become more promising than ever before. This project will focus on the ecological effects of chemical communication in marine systems, demanding significant integration of biology and chemistry, involving active participation of young scientists in hypothesis building and testing, and training students in research methods and communication. In this study, the Florida red tide dinoflagellate Karenia brevis (= Gymnodinium breve) will be used as a model system for understanding how phytoplankton natural products directly mediate critical interactions such as predation, which affects population and community structure. Phytoplankton chemistry may also induce food-web cascades affecting multiple ecosystems, amplified by the movement of blooms over vast distances. Indirect evidence suggests that some harmful algae use natural toxins to deter grazing by zooplankters, shellfish, and planktivorous fish, or as allelopathic agents against competing microalgae, perhaps contributing to bloom proliferation. This study will test the hypothesis that chemical compounds produced by Karenia brevis defend it against grazing by the co-occurring copepod Acartia tonsa. Chemical fractionation guided by copepod behavioral and physiological feeding assays will be used to isolate antifeedant compounds from K. brevis extracts. Ecologically active compounds will be identified by spectroscopic techniques such NMR spectroscopy and mass spectrometry (including LC-MS). This research will provide adaptable methods for studying food-web and competitive relationships between unicellular organisms and their enemies, effectively decoupling chemical from morphological and nutritional factors. Students involved in interdisciplinary science need to develop strong communication skills for bridging fields and to acquire a breadth of experience without sacrificing scientific rigor and depth in their specialty. Towards these ends, two new educational opportunities have been designed. First, a new seminar series is planned for graduate and upper-undergraduate students, researchers, and faculty on the intersection of research, policy, and communication with non-scientists, using harmful algal blooms as an example of science that holds public interest. Second, a new interdisciplinary course will be developed for graduate and upper-undergraduate students on methodologies for the discovery of novel bioactive molecules that function as cues among aquatic organisms. This project was originally funded as a CAREER award, and was converted to a Presidential Early Career Award for Engineers and Scientists (PECASE) award in May 2004.