Marine Science

Session I

Alexandra Kim, "Impact of Hematodinium Perezi on Molting and Survival of Blue Crabs"

Hematodinium Perezi is a parasitic dinoflagellate that infects decapods, including the American blue crab. This research explored the impact of the parasite as well as other environmental factors on the molting and survival of the crabs. Using data collected from lab and field experiments, various analyses were carried out in R. Factors such as salinity, initial short carapace width and size change were used to determine effects on both infected and naive crabs. Analyses were carried out at two separate temperatures, 20 and 25 degrees Celsius. These were used to build models in order to reflect and predict the probability of survival and molting based on these criteria. Based on the computations, it was found that infection plays a significant role on the molting probability of the crabs at 25 degrees

Student Major(s)/Minor: Computational & Applied Math & Stats - Mathematical Biology

Advisor: Dr. Megan Tomamichel

Libby McClough, "Modeling Ecological Interactions in Coastal Marshes as Influenced by Climate Change-Induced Range Expansion of Fiddler Crabs"

The tightly-linked ecological interactions between fiddler crabs, parasites, and cordgrass are changing as a result of climate change-induced northward range expansion among fiddler crabs. These crabs have been observed to experience “parasite escape”, resulting in an increase in fitness, potentially explaining an observed change in cordgrass belowground and aboveground biomass growth in expanded regions. Here, we develop a differential equation model that captures how parasite-released fiddler crab burrowing affects nutrient cycling and root disruption, and the impacts of these factors on cordgrass growth. Results suggest that fiddler crabs activity in the expanded range may promote greater biomass allocation into aboveground biomass over belowground biomass as compared to the historic range. 

Student Major(s)/Minor: Biology and CAMS majors

Advisor: Dr. Megan Tomamichel 

Session II

Isabel Volden, "Comparing Gracilaria vermiculophylla Epibiota Across Ecological Scales"

Across eukaryotes, there is a tremendous diversity of life cycles. Yet, we lack a mechanistic understanding of the factors influencing the evolutionary maintenance of this diversity. The haploid-diploid red macroalga Gracilaria vermiculophylla has colonized soft bottom habitats where algal spores cannot easily grow. Despite morphological similarity, the haploid phase (the gametophyte) of the life cycle is lost. Recent work in the lab has identified phenotypic differentiation among male gametophytes, female gametophytes, and diploid sporophytes, including differences in their associated microbial communities. We sampled Gracilaria vermiculophylla thalli from sites along the Delmarva Peninsula. Using amplicon sequencing, we will characterize their epibiota to analyze how microbial communities vary across different life cycle phases and ecological conditions, such as salinity gradients. Identifying the baseline microbial compositions under these differing conditions will therefore allow for future experimental manipulation to fully investigate the role of microbes in this alga’s invasion and altered life cycle.

Student Major(s): Undeclared

Advisor: Dr. Stacy Krueger-Hadfield