Date of Award


Degree Type


Degree Name

Master of Science in Biological and Environmental Sciences (MSBES)


Ecology and Ecosystem Sciences


Biological Sciences

First Advisor

Jonathan Puritz


The Atlantic horseshoe crab, Limulus polyphemus, is a commercially, ecologically, and economically important species. Current management practices of this species may not be well informed enough to avoid jeopardizing the future health of these animals. This thesis argues that population differences, as defined by morphometrics, behavior, and genomics, may be visible over smaller geographic scales than current fisheries management observes. Specifically, this work focuses on three states in southern New England: Rhode Island, Massachusetts, and Connecticut. Ten sampling locations were observed over two years, 2020-2021, from which over 500 crabs were sampled. Width and weight data were collected to assess whether size differs by location using non-parametric approaches. Tagging data from the US Fish and Wildlife Service was analyzed to assess whether small, localized movement patterns or broad range geographic movement was more prevalent throughout the range. Tissue samples were processed to extract genetic information (single nucleotide polymorphisms) to inform upon adaptive and migratory traits across the range. Morphometric data identified that 36% of pairwise comparisons were significant. Tagging data showed 69% of recaptured crabs were caught in the same water body they were originally released. Genomics tools suggested that outlier loci, more so than neutral loci, were driving the population structuring observed. Cumulatively, these results suggested that population differences can be observed over a smaller scale than currently employed for fisheries management.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.