Inter-Research > AME > Prepress Abstract

AME prepress abstract   -  DOI:

Microbial ecology of coral-dominated reefs in the Federated States of Micronesia

Amy Apprill*, Henry Holm, Alyson E. Santoro, Cynthia Becker, Matthew Neave, Konrad Hughen, Angela Richards DonĂ , Greta Aeby, Thierry Work, Laura Weber, Sean McNally

*Corresponding author:

ABSTRACT: Microorganisms are central to the functioning of coral reef ecosystems, but their dynamics are unstudied on most reefs. We examined the microbial ecology of shallow reefs within the Federated States of Micronesia. We surveyed 20 reefs surrounding seven islands and atolls (Yap, Woleai, Olimarao, Kosrae, Kapingamarangi, Nukuoro and Pohnpei), spanning 875,053 km2. We found consistently higher coral coverage on the reefs (mean 36.9% +/- 22.2 SD; max 77%) compared to macroalgae (mean 15.2% +/- 15.5 SD; max 58%) and low abundances of fish. Reef waters had low inorganic nutrient concentrations and were dominated by Synechococcus, Prochlorococcus and SAR11 bacteria. The richness of bacterial and archaeal communities was significantly related to interactions between island/atoll and depth. High coral coverage on reefs was linked to higher relative abundances of Flavobacteriaceae, Leisingera, Owenweeksia, Vibrio, and the OM27 clade as well as other heterotrophic bacterial groups, consistent with communities residing in waters near corals and within coral mucus. Microbial community structure at reef depth was significantly correlated with geographic distance, suggesting that island biogeography influences reef microbial communities. Kosrae’s reefs, which hosted the highest coral abundance and diversity, were unique compared to other locations; seawater from Kosrae’s reefs had the lowest organic carbon (59.8 to 67.9 μM), highest organic nitrogen (4.5 to 5.3 μM) and harbored consistent microbial communities (>85% similar), which were dominated by heterotrophic cells. This study suggests that the reef water microbial ecology on Micronesian reefs is influenced by the density and diversity of corals as well as other biogeographical-related features.