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Pathobiologists Seek Explanation
for Fish Kill in East Hampton Lake
January 24, 2000

UConn scientists have once again stepped in to lend their expertise in resolving an environmental crisis in Connecticut. A team of pathologists is working with the Department of Environmental Protection to determine the cause of a massive fish kill in East Hampton's Lake Pocotopaug.

About four weeks ago, residents around the lake first spotted something unusual: hundreds upon hundreds of fish congregating in large groups at the tributaries, as if they were trying to get out of the lake. The DEP was called in and began taking fish and water samples. Meanwhile, thousands of dead fish of every species started washing up on shore or were found floating throughout the 510-acre lake.

UConn pathologist Richard French lives in Marlborough, nearby the lake. After hearing reports of the fish kill, he stopped by to observe the situation and collect samples of his own.

"It was hitting close to home, so I felt I needed to do something, besides the fact that as a university pathobiologist, it's my responsibility to do what I can to help solve a crisis like this," says French.

Winter is an odd time of year for this size and type of fish kill, he says. From initial tests on the samples he collected, French detected evidence of disease, so he called DEP to offer the services of the Connecticut Veterinary Diagnostic Laboratory, which is based at UConn. The lab recently pinpointed the probable cause of the Long Island lobster kill and tested birds for the West Nile virus.

The extensive testing procedures required live fish, so DEP went fishing in Lake Pocotopaug to catch the six primary species inhabiting the lake: white perch, yellow perch, largemouth bass, carp, bluegill and chain pickerel.

A necropsy was conducted on each fish, but it didn't take a microscope to see evidence of a problem. The gills and fins on each fish had turned shades of red - the result of becoming engorged with blood, says French. He believes a disease that affects the gills is suffocating the fish, and their instinct to swim into the tributaries represents an effort to find more oxygen.

Over the next week, more complex tests will be conducted. Salvatore Frasca, an assistant professor of pathobiology who specializes in finfish pathology, will look at multiple tissues to define any signs of disease and to determine if the findings are consistent across species. Meanwhile, Sylvain DeGuise, an assistant professor of pathobiology and environmental toxicologist, will conduct toxicological analysis of the tissues harvested. Knowing what organ is affected helps determine whether or not a contaminant is involved and narrows the range of possible contaminants.

The lake is noted for its algae blooms, which can produce toxins, but algae blooms only occur during warm summer weather. French says the fish kill could be the result of a contaminant in the water or bacterial overgrowth.

Once testing and analysis are completed, the pathology collected at UConn will be turned over to the DEP to be used in conjunction with other tests being conducted at federal laboratories.

Janice Palmer