OLI Grant: Sponge Associated Microbial Communities: Biodiversity and Biogeochemistry


Grant Funded: 2005

The tropical sponge Chondrillanucula harbors a variety of microbial symbionts, including photosynthetic cyanobacteria and possibly nitrifying bacteria. Rates of nitrate release from C. nucula have been shown to greatly exceed water column or sedimentary rates and thus may constitute a large source of nitrate to the reef ecosystem. The primary nitrifying bacteria involved in this sponge-associated nitrate production, however, have not yet been identified. In this study, we will study the diversity of nitrifying symbionts in C. nuculacollected from the Cayo Enrique reef near Puerto Rico. We will also measure net and gross rates of nitrification associated with the sponges to identify whether nitrate produced in this association is reassimilated by the sponge or its symbionts. Finally, we will investigate the possible linkage between nitrogen fixation and nitrification that has not previously been evaluated. The nitrogen cycle dynamics will be determined using a combination of nitrogen isotope tracer techniques and molecular genetic techniques to identify the key microbial players in this novel biogeochemical habitat.