Woods Hole Oceanographic Institution

Rebecca J Gast

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Image of amoebae on Mnemiopsis comb plate. Phase contrast image at 20X magnification. (R Gast WHOI)

Analysis of a Protist Assemblage of the Coastal Ctenophore, Mnemiopsis leidyi

Anthony G. Moss Auburn University
Andrew Rogerson Nova Southeastern University
Barbara K. Sullivan University of Rhode Island

This collaborative project focuses on the characterization, phylogeny, and functional impact of a specific assemblage of epicommensal protists associated with the lobate ctenophore, Mnemiopsis leidyi, a keystone predator of marine coastal planktonic communities extending from the Gulf of Mexico along the Atlantic Coast to New England. The species diversity, relative species abundance of each member of the assemblage, geographic range and infectivity of this assemblage will be documented by a team of collaborating researchers from four institutions.

Understanding the range of the microbe-host interaction is critical to a more complete understanding of the biology of Mnemiopsis. Mnemiopsis can alter community structure through voracious predation on zooplankton populations to the point where this resource becomes limiting to other predator species (i.e., fish). Mnemiopsis is also a globally invasive organism that has demonstrated its capacity to disrupt the trophic structure of coastal communities worldwide, with severe economic consequences. Dense protist assemblages may alter reproductive capacity and feeding in Mnemiopsis, and could be transferred to new hosts in new environments. As such, understanding the biology of this assemblage, its impact on the host, and its capacity to infest alternate species, could illuminate the mechanisms and effects of Mnemiopsis invasion into a new environment.

In order to obtain the most comprehensive possible profile of the assemblage, molecular phylogenetic techniques will be combined with conventional protozoological identification methods and cellular ultrastructural data to provide detailed information about each component species. We will seek to identify the source of the cells within the environment (i.e. whether derived from the water column or benthic communities). We will also attempt to determine whether individual species can be transferred to higher trophic level predators such as larger gelatinous predatory ctenophores (e.g., Beroe) or fish.

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