Analysis of the microbial base community in the nesting environment of American Horseshoe Crabs

Student: Arianna Leo
Mentors: Kirk Bartholomew, Mark Beekey, Jennifer Mattei
Major: Biology

The American horseshoe crab, Limulus polyphemus, is an ecologically and economically important invertebrate species with a wide distribution along the Atlantic and Gulf of Mexico coasts. Investigation of the sediment surrounding horseshoe crab nests in the Long Island Sound has lead to the discovery of an invertebrate species assemblage that seems to be found in consistent association. The objective of our current work is to extend the nest community analysis to the microbial level. Accordingly, we constructed 16S rRNA metagenomic libraries of environmental DNA isolated from 15 nest and 4 out-of-nest sediment samples at varying depths for next generation sequencing. We have obtained in excess of 30,000 sequences of the 16S rRNA variable 4 region from each sample which has allowed a comparison of the prokaryotic communities at each depth within and between nests and to the surrounding environment. Analysis of the sequence data to date indicates significant differences in microbial community composition between nest samples and those derived from the surrounding environment. However, no significant differences were found between samples at different depths, suggesting that the “nest” environment has some influence on the microbial composition of each sample.