Fowler and Greenberg receive funding for study of crab parasites

Amy Fowler, Assistant Professor, Environmental Science and Policy, and Sarah Greenberg, Master’s Student, Environmental Science and Policy, received $2,769 from Washington Biologists’ Field Club to support Greenberg’s master’s research examining castrating parasites of an estuarine crab host.

Focusing on Rhithropanopeus, a species of crab native to the Atlantic coast, Greenberg wants to know how environmental salinity shapes the spatiotemporal distribution of host-parasite relationships, how salinity affects the survival and metamorphosis of parasite larvae, and how parasites affect the reproduction and abundance of the host crab.

Greenberg will place traps in low- and high-salinity sites in three Chesapeake Bay tributaries–the Potomac, Rappahannock, and James Rivers. She will collect crabs from three traps per site every two months for eighteen months. She will count the crabs, dissect them to determine whether they have parasites, and determine host-parasite seasonality.

For those crabs that are infected, Greenberg will dry the body, sexual organ, and hepatopancreas tissue to gauge atrophy, as the parasites are suspected castrators. Greenberg will also subject parasitic larvae to several salinities to investigate if salinity impacts survival and metamorphosis.

Mud crabs are one of the most abundant species living in oyster reef communities. Understanding the extent to which parasites can influence individual and reproductive success is crucial. Abiotic tolerances, such as salinity, give insight to a species’ geographical location and how their distribution influences local fauna.

One of the parasites of interest has a close relative that castrates blue crabs in the Gulf of Mexico. This parasite has not been found infecting blue crabs of the Chesapeake Bay. However, if it were to be introduced to the Chesapeake Bay (through human-mediated introductions), it may cause great ecological and economic damage. This research thus provides an understanding of the ecological and conservation-related impacts of invading parasites that may help predict the future of estuarine communities under continued invasion pressures.

Funding for this research began in March 2021 and will end in late February 2022.

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