Meeting Abstract
Reef-building corals form complex relationships with a wide range of microbial partners, including symbiotic algae in the family Symbiodiniaceae and various bacteria. The coral’s algal and bacterial communities can be shaped to varying degrees by environmental context. Sedimentation can structure a coral’s microbial community by altering light availability for symbiotic algae, triggering the coral’s stress response, or serving as a reservoir for both pathogenic and essential bacteria and algal symbionts. To examine the influence of sedimentation on a coral’s microbial community, we used 16S rDNA and ITS-2 amplicon sequencing to characterize the bacterial and algal communities associated with the massive scleractinian coral Porites lobata across a naturally occurring sedimentation gradient in Fouha Bay, southern Guam. In addition to sedimentation, we are also investigating the relative contributions of other environmental parameters (i.e., temperature, salinity) to the coral’s algal and bacterial communities and how these communities differ within a single colony (i.e., edge vs center). Along this gradient we see that sedimentation is higher and salinity and temperature are generally lower closer to the river mouth compared to the reef crest. Together these variations in environmental parameters play a strong structuring role in the coral’s algal community and microbiome and these spatially structured communities may help corals thrive across this steep environmental gradient.
