Gut-Associated Microbial Symbionts of the Marsh Fiddler Crab, Uca Pugnax

摘要

Digestive associations between marine invertebrates and resident (attached) microbial communities may play a critical role in host physiology and involve previously unidentified microbial species. The overarching goal of this thesis was to characterize the ecology and genetic diversity of resident gut microbes to advance our understanding of their interactions with their host, the marsh fiddler crab, Uca pugnax. Furthermore, we assessed whether microbes benefit the host by contributing extracellular enzymes along the digestive tract. This is the first report of the eccrinid protists, Enteromyces calllanassae and Enterobryus sp., inhabiting U. pugnax. The greatest abundances of both bacteria and protists were documented in the host stomach and hindgut. For these sections, we have described morphologies, measured abundances and characterized the genetic diversity (bacteria) of resident microbes. Presence and abundance of the Eccrinales protists depends on host molt stage as all eccrinid biomass is shed with the host's molt. In intermolt crabs, both bacterial and protozoan symbionts appear to be consistent features of the stomach and hindgut.