Microbial community structure shows differing levels of temporal stability in intertidal beach sands of the grand strand region of South Carolina

Studies of microbial community structure in intertidal and supratidal beach sands along the California and Gulf of Mexico coasts have begun to reveal geographical patterns in microbial diversity through the use of next generation sequencing technology. Only a few studies have targeted communities along the Eastern seaboard, leaving a variety of microbial ecosystems uncharacterized. In this study, we examine the microbial community structure within three South Carolina beaches along the Grand Strand via sequencing of the V4 region of the 16S rRNA gene to discern relationships between diversity and temporal or regional factors. Gammaproteobacteria, Planctomycetes, Acidobacteria, and Actinobacteria dominated the composition of these beaches. Diversity analyses revealed that highly diverse communities were similar in overall composition and diversity but showed different levels of community structure stability over time. The community structure in Pawleys Island sands showed no significant change over time, while Garden City experienced significant shifts between each sampling date. Community structure also differed between beaches and, to a lesser degree, sampling date. These data provide evidence of the high microbial diversity within these beach sands and suggest that even though beaches of the same geographic region can show similarity in composition and diversity at a particular timepoint, the nature of their community structure and underlying diversity may differ comparatively and over time.