The Delaware Bay supports the world’s largest spawning population of horseshoe crabs (HSC). The massive abundance of eggs deposited on the beach is a critical resource for many animals including migratory shorebirds, gulls, and fish. Adjacent intertidal oyster farming activities may influence HSC egg distribution, potentially impacting food availability for organisms foraging on the eggs. Beach characteristics may also influence HSC egg distribution, potentially confounding the effect of oyster farms. This research examined how several beach characteristics were associated with the distribution of HSC eggs, and if any associated beach characteristics confound potential associations between farms and egg distribution given the limited and fixed distribution of farms available for study. In Spring 2021 and 2022, HSC egg surveys were conducted in four paired farm-control plots (90 m x 180 m) across a 2 km stretch of beach in Delaware Bay. In 2022 six beach characteristics were examined in each plot: depth of anoxic layer, beach width, beach slope, sand grain size composition, percent cover of Spartina alterniflora, and adjacent land use. Correlation analyses indicated that beach characteristics were not significantly associated with the HSC egg distribution. Additionally, there was no consistent pattern between the beach characteristics and plot type (farm vs. control). These findings suggest that beach characteristics were not confounding factors for other studies addressing the relationship between oyster farms and HSC egg distribution at this site. 

Primary Presenter: Catherine Carrion, Virginia Polytechnic Institute and State University (catherinec20@vt.edu)

Authors:

Catherine Carrion, Virginia Polytechnic Institute and State University   (catherinec20@vt.edu)

David Bushek, Haskin Shellfish Research Laboratory, Rutgers University  (bushek@hsrl.rutgers.edu)

Elizabeth Bouchard, Haskin Shellfish Research Laboratory, Rutgers University  (ehb52@hsrl.rutgers.edu)