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Pathologists Investigate
Ailing Lobsters in Sound
December 6, 1999

First dead crows, now dead lobsters are the center of attention for the Department of Pathobiology. And the work being done by Richard French and his colleagues at the Connecticut Veterinary Diagnostic Laboratory, could solve a deadly and costly mystery that is plaguing the lobster industries in Connecticut and Maine.

In September, Long Island lobstermen, particularly those from the western sound, started pulling up traps that contained many dead or dying lobsters. According to the Department of Environmental Protection, the catch is way down this year, by 34 percent in Stamford and by 63 percent in Greenwich.

When reports about the lobster kill started to surface, the UConn lab was deep into the investigation of the West Nile encephalitis virus and the testing of crows. But as soon as the decks cleared, Richard French, a veterinary pathologist whose research interest is shellfish diseases, contacted the Department of Environmental Protection to see if he and the lab could lend a hand. Within days, the agency delivered lobsters to Storrs, and within a week the UConn team, including French, and fellow veterinary pathologists Sylvain De Guise and Salvatore Frasca, had pinpointed the probable cause of the lobster deaths.

French says they've tentatively identified a tiny parasite called a para-moeba as the culprit. Paramoebas are single-cell organisms, some of which are free-living in the marine environment. But French says what they may be looking at is a parasitic form of the organism.

After conducting a full necropsy on dozens of lobsters, the researchers found evidence of the parasite in the main nerve chord, as well as in the antennae, eyes and other organs. French says the parasite causes an inflammation of the lobster's nervous system and he is trying to prove that it is this which causes them to go limp and eventually die.

In Maine, the lobster die-off began three years ago, but in smaller numbers than Connecticut is now experiencing. Researchers at the University of Maine's Lobster Institute had determined that bacteria were a possible cause. In a recent interview with a reporter, the director of the institute said the lobster's nervous system was "not a place that we ever thought to look."

Now, the Maine Department of Marine Resources has asked UConn to determine if the paramoeba contributed to its lobster die-off and has sent lobsters to the Storrs campus for investigation.

Still to be answered is why the paramoeba, which has always existed in marine waters, is now able to make some - but not all - lobsters sick. French suspects something else may be weakening the lobster's immune system, making it susceptible to the paramoeba's deadly grip.

"What we don't know yet, is if the paramoeba is the primary agent or if it is an opportunistic agent which comes in secondarily," says French. So about 10 days ago, the UConn team began a second round of testing on Maine and Long Island lobsters to pinpoint what stressors may be compromising the lobster's immune system. Three possible factors include: thermal stress caused by warmer water, anoxia or a lack of oxygen at the ocean floor, and environmental contaminants such as pesticides.

For lobster lovers, the disease does not pose any threat to humans other than to their wallets. The lobster kill has wiped out hundreds of thousands of lobsters, among them egg-bearing females, so the effects of the disease could be felt for years.

For Maine, the lobster industry is usually worth $130 million a year and for Connecticut it's been generating about $35 million. But a month ago, dozens of Long Island lobstermen gave up on setting their traps. They are seeking state and federal aid for what is adding up to a huge financial loss.

Although they don't yet know it, some aid has already arrived. Connecticut Sea Grant, based at UConn's Avery Point campus, has just awarded $5,000 to French to help fund further research. It's hoped that any answers the UConn team comes up with will help limit future die-off or, at least, help predict it.

Janice Palmer