Not Just Summer Heat - Tropical Fish are moving in as Long Island Sound warms

Conneticut Post -    Long Island Sound is changing. Biologists who study the Sound say that they are seeing different fish and crabs, and in just about every case, these new species are those that were better known hundreds of miles to the south decades ago. Meanwhile, the sea creatures that are better adapted to colder water are in distress in the Sound, and are either dying off or moving north. Penny Howell, a marine fisheries biologist with the state Department of Enviormental Protecton said that the troll surveys that the DEP does a number of times a per year, indicate that the "warm adapted" species are doing well, while the "cold adapted" species "have lost their advantage as water temps slowly rise." Cold water fish in trouble include the Atlantic mackerel, the four-spotted flounder, the little skate, the red hake, the windowpane flounder and the sea raven.

"Long Island Sound represents a kind of dividing line between the warm-adapted species of the North Atlantic and the cold-adapted ones," said Nancy Balcom, the associate director of Connecticut Sea Grant. Complicating this picture are scores of invasive species in the Sound, from the bread-crumb sponge to the Asian shore crab, one interloper, the lion fish, is usually thought of as a denizen of tropical coral reefs.

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  It turns out that taking the temperature of the Sound is a lot more involved than wading in and sticking a thermometer in the water. Because the Sound is relatively shallow, about 50 to 100 feet in most places, water temperatures change quickly as spring turns to summer, and again as fall becomes winter. "The data available for water temperatures is fairly limited," said James O'Donnell, a University of Connecticut Scientists whose studying water temperatures and circulation in the Sound. A lot has been learned already. For example, the Sound is remarkable in that, of all the salt water bodies in the world, it has the greatest temperature variation between summer and winter - about 77 degrees Fahrenheit, or 25 degrees Celsius.

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  As for salinity, the Sound is "significantly fresher" than the ocean; it's about one-half to one-third less salty than the Atlantic. 90% of the freshwater influx comes from the Thames, the Connecticut, the Housatonic and the Hudson Rivers.

• Warm-water species that have come up in the DEP nets include the glass eyed Snapper and the lizard fish, moonfish and bluecrab. While the numbers of lobster and winter flounder are strikingly down.