Date of Award

8-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Biology

Thesis Sponsor/Dissertation Chair/Project Chair

Paul Bologna

Committee Member

Matthew Schuler

Committee Member

Scott Kight

Abstract

Libinia emarginata, commonly known as the portly or common spider crab, is predominantly herbivorous and native to the east coast of the United States. In Barnegat Bay, New Jersey, L. emarginata is a prominent member in eelgrass communities, but is widespread among numerous benthic habitats. Eelgrass beds in Barnegat Bay are also used as settlement sites for blue mussels (Mytilus edulis), which show episodic recruitment events in the spring. These events are ephemeral and variable in timing, location, and quantity. Unlike more extensively studied crabs, such as Callinectes sapidus and Carcinus maenas, there is limited research on the interactions that L. emarginata has with mussels. This study aimed to evaluate whether L. emarginata could recognize this episodic event as a potential windfall of trophic resources like other crab species or merely rely upon the abundant algae. Crabs and mussels were collected from Barnegat Bay, both were sorted into three size categories, and subjected to a series of experiments to determine size-specific consumption preferences and the choice between mussels and algae (Ulva lactuca). Results indicated that small crabs (0-1 yr. old) did not consume mussels, possibly due to their age and inexperience. Medium crabs (1-2yrs.) preferred small mussels, but actively fed on all sizes of mussels offered as well as algae. Large crabs (2+ yrs.) showed no preference for mussel size, but consumed more mussels and preferred mussels to algae. These findings suggest that predation behavior in L. emarginata is influenced by age and size, with larger, older crabs more capable and inclined to consume mussels, while younger crabs opt for more familiar and easily accessible algae. Understanding these dynamics is crucial for comprehending the ecological roles and impacts of L. emarginata as a consumer in coastal marine communities.

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