Bioturbation by the marine polychaete Capitella teleta alters the sediment microbial community by ingestion and defecation of sediment particles

Deposit-feeding benthic invertebrates are known to modify sediment structure and impact microbial processes associated with biogeochemical cycles in marine sedimentary environments. Despite this, however, there is limited information on how sediment ingestion and defecation by marine benthos alters microbial community structure and function in sediments. In the current study, we used high-throughput sequencing data of 16S rRNA genes obtained from a previous microcosm study to examine how sediment processing by the marine polychaete Capitella teleta specifically affects sediment microbiota. Here we show that both sediment ingestion and defecation by C. teleta significantly alters overall microbial community structure and function. Sediment processing by C. teleta resulted in significant enrichment of sediment microbial communities involved in sulfur and carbon cycling in worm fecal pellets. Moreover, C. teleta's microbiota was predominantly comprised of bacterial functional groups involved in fermentation, relative to microbiota found outside of the host. Collectively, results of this study indicate that C. teleta has the ability to alter microbial biogeochemical cycles in the benthic sedimentary environment by altering microbial assemblages in the worm gut, and in the sediment ingested and defecated by worms as they feed on sediment particles. In this sense, C. teleta plays an important role as an ecosystem engineer and in shaping nutrient cycling in the benthic environment.