Rapid turnover of ciliate community members in New England tide pools

The rocky intertidal zone represents a dynamic habitat marked by considerable species richness, which has been well-documented for invertebrates and macroalgae. This high biodiversity exists in the context of extreme fluctuations in abiotic factors such as temperature, salinity and pH that occur during each tidal cycle. Despite these attributes, few studies have focused on microbial diversity in tide pools, including analyses of the ciliate communities that are the focus of this study. We investigated the spatial and temporal distributions of ciliate species across the intertidal environment at sites in Maine and Connecticut, USA. Our study used a DNA fingerprinting technique, denaturing gradient gel electrophoresis (DGGE), which allows for genetic analyses of abundant community members. We investigated how ciliate diversity changed across several spatiotemporal scales: (1) between the open ocean and tide pools, (2) among different tide pools at varying distances from the low tide mark and (3) at differing times within a tidal cycle. In addition, we examined the differences between active and non-active members in these extreme environments by investigating diversity of both ribosomal DNA and RNA. In both Maine and Connecticut, we found abundant ciliate taxa that are either rare or absent in the open ocean, and that appear to quickly dominate tide pools once they are isolated from the open ocean. We also found that ciliate distributions within the tide pool community are complex and variable across spatial and temporal scales.