Microscopic Islands: Theory of Island Biogeography for Aquatic Pathogens

The theory of island biogeography, seminal to modern ecological thinking, has been invoked hundreds of times to explain colonization sequences and species richness on “islands” of many sizes and in many locations. These applications have overwhelmingly focused on macroorganisms, practically ignored microorganisms, and never have been considered in the context of disease ecology. Organic-rich marine and freshwater aggregates (synonyms include: marine snow, freshwater snow, organic detritus, and bioflocs) serve as “microscopic islands” for microbes in aquatic environments.

Our multi-disciplinary team from Old Dominion University (Fred Dobbs), the University of Connecticut (J. Evan Ward), the University of Minnesota Duluth (Randall Hicks), and the University of Georgia (John Drake) is characterizing aggregates and investigating their role in the persistence of aquatic pathogens. We will evaluate whether fundamental concepts of island biogeography apply to bacterial pathogens that enter aqueous environments from a point source of pollution and are subsequently incorporated into aggregates. Our long-term goal is to bring a community-level approach to studies of infectious diseases in aquatic environments. This inquiry will be the first to test island biogeography theory as it applies to aquatic pathogenic microorganisms.

As part of this project, the Hicks lab is using genetic profiling of bacterial communtiies (T-RFLP) to measure how species richness changes as a function of aggregate size and distance from colonizing sources to (a) test island biogeography theory applied to aggregates (microscopic “islands”), and (b) evaluate if the species richness of the resident bacterial community on aggregates influences the colonization success and persistence of introduced pathogenic bacterial species.

This project will start in 2009 and continue for the next four years with support from the National Science Foundation.




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