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Blue crab populations along the Atlantic coast could get a boost from a research project being undertaken by scientists at Old Dominion University and the Virginia Institute of Marine Sciences under a $2.4 million grant from the National Science Foundation (NSF) and National Institutes of Health (NIH).

Mark Butler, professor of biological sciences at ODU, and Jeffrey Shields, professor of environmental and aquatic animal health at VIMS, lead the research team. The five-year project will focus on the effects of environmental change and fishing on outbreaks of the pathogenic parasite Hematodinium, which can be especially deadly to blue crabs.

Research will take place in small coastal estuaries of the Delmarva Peninsula.

A key goal of the project is to determine the role that fishing pressure plays in Hematodinium epidemics. Butler said intensive catches of blue crabs removes adults, which are more disease resistant, while intensifying the population of more disease-susceptible juveniles (which, when trapped by crabbers, must be thrown back). "The effect of fishing pressure on disease has received little attention, which is surprising given the increasing reports of diseases in marine populations that experience significant exploitation," he said.

Another goal is to weigh the effects of habitat degradation on Hematodinium outbreaks.

The researchers propose to produce "epidemiological models capable of integrating local environmental change and fishing pressure with disease dynamics," according to their project summary. They say that such models could have broad application, not only to crabs, but also to other finfish and shellfish populations.

NSF's Directorates for Biological Sciences and Geosciences and NIH's Fogarty International Center and National Institute of Environmental Health Sciences announced on Oct. 29 that they would fund this project under the Ecology of Infectious Diseases (EID) program. Seven other projects, all of which involve studies of the interaction between the environment and disease processes, also were funded.

The EID program is designed to investigate ways that environmental changes are related to the emergence and re-emergence of infectious diseases over the last several decades.

Hematodinium, which is a dinoflagellate related to the more widely known Phiesteria that causes fish kills, has attacked crab populations for decades in places such as France and Scotland. But the parasite was only first reported about 15 years ago in the Mid-Atlantic, where studies have now connected it to sporadic (warm weather) kills of blue crabs. It grows in the crab's blood, consuming the hemolymph protein that transports oxygen. Crabs suffering from a heavy infection of Hematodinium are lethargic and eventually die from lack of oxygen.

The research team, which also includes Harry Wang and Kimberly Reece, associate professors of marine science at VIMS, will undertake outreach programs related to the project. They will sponsor an annual meeting with fishermen, resource managers and environmentalists to share their findings. They will send their graduate-student team members into high schools to make presentations on environmental change and disease. Finally, they will develop a Web site on Hematodinium at www.vims.edu/~jeff/hematodinium.htm.

This article was posted on: November 5, 2007

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