Doliolid Blooms: What Are the Driving Variables? Investigations of Trophic Interactions

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It is well known that neritic regions of subtropical oceans experience episodic occurrences of pelagic tunicate blooms. However, little is known regarding the processes that regulate these populations or their ecological significance. Based on sporadic field observations and a relatively small number of laboratory studies, it is understood that theoretically blooms of the Thaliacea, specifically the doliolids, may be particularly important because of their enormous and rapid asexual reproductive capacity. Blooms of over 1,000 zooids m-3 are reported from most of the world's continental shelves. Large blooms of doliolids have the potential of restructuring the trophic structure of shelf pelagic ecosystems by limiting copepod production via consumption of eggs and shunting primary production to the benthos and the microbial loop via fecal production. Although much has been learned via careful laboratory studies, investigation of the processes that govern the development of doliolid blooms cannot be satisfactorily simulated in the laboratory and, until recently, methods to investigate key aspects of trophic interactions between zooplankton, their prey, and their predators in situ have been lacking. In this project the investigators will conduct a field-based study in which classical and proven zooplankton ecology methods will be merged with new molecular based approaches for assessing gut contents to address several fundamental questions concerning doliolid trophic interactions during summer blooms on the South Atlantic Bight continental shelf.Two aspects of the project may be considered potentially transformative. First, it will be among the first to systematically apply zooplankton molecular gut content analytical methods in situ, potentially revolutionizing the field of zooplankton ecology. It is of note that the need for new tools to investigate zooplankton trophic processes has been clearly identified by the science community as a major limitation to the field. Second, the project will explore a paradigm shifting hypothesis that doliolid blooms are controlled not by direct predation, nutrient limitation, or advective oceanographic processes, but by a changing food particle environment.The research focuses on a central theme, trophic interactions, within the diverse field of marine plankton studies, and therefore will be of interest well beyond the specific focus of the project. To a broader degree, the study will serve to help bridge the fundamental divide in modern biology that exists between molecules, organisms, and ecology. An important component of the project will involve training and increasing representation of underrepresented students in STEM fields. One graduate student and three undergraduate students will be supported and trained. Through well established relationships with two Historically Black Universities, both of which have Marine Science programs (Hampton University and Savannah State University), the investigators will aggressively recruit students. Additionally, one of the investigators is a young assistant professor at Hampton University and this project will provide her opportunities to advance her research career, improve research infrastructure at Hampton, and increase student exposure to research. Finally, this project will take advantage of established International relationships with Nordic researchers who are actively engaged in similar research but focused on Appendicularians and other gelatinous pelagic species. The project will also support the participation of US marine scientists in the upcoming Molecular Trophic Interactions II symposium being organized in Savannah in 2009.