Giant jellyfish invade northern Gulf of Mexico

By: Melissa Schneider / Published: Aug 16,  2000

Ocean Springs, MS — Giant "jellies" up to two feet in diameter have taken up residence in the northern Gulf of Mexico causing swimmers and fishermen to do a double take when they first spy them. Known as the Spotted Jellyfish, these creatures don't pose a threat to swimmers because their sting is mild compared to some of the natives like the Sea Nettle. However, the jellies' threat to the area's ecosystems is yet to be determined. Similar alien jellyfish have caused major disruptions in marine fisheries in Europe in some cases driving out other marine life. "One of the biggest worries is that these jellies will feed directly on the eggs and larvae of the area's fish, shrimp and crabs. And doing so could have a serious effect on the commercial fisheries on the Coast," says Dr. Monty Graham, senior marine scientist at the Dauphin Island Sea Lab in Alabama.

This could be detrimental to the Gulf's commercial fisheries industry. Gulf shrimp are the nation's second most valuable fishery, trailing only Alaska salmon. And the Gulf's commercial fisheries landings account for 40% of all U.S commercial landings.

In response to this invasion, the Mississippi-Alabama Sea Grant Consortium is providing emergency research funding to learn more about these invaders and their potential threat. Graham and Harriet Perry, Director of the Center for Fisheries Research & Development at the Gulf Coast Research Lab in Ocean Springs, MS are heading up the research team. Though only in the early stages of their investigation, they have already found indications that the jellies are reproductively active and growing to their large size due to the algae-rich Mississippi Sound.

"Normally, this species of jellyfish is found in the Caribbean and only grows to six or eight inches in diameter," says Perry. "Some of the things we're investigating are how widespread the invasion is, what their feeding habits are, how much they eat, and whether they can survive over the winter months in the Gulf waters."

Arial surveys have shown that these jellyfish congregate in large patches in some cases more than 2,000 jellyfish clustering in an area the size of a football field.

Native to Australian coastal waters, the Spotted Jellyfish (Phyllorhiza punctata) have been migrating to the Caribbean for the past two decades, but have not been seen this far north. Their coastal invasion began in early June when it is believed the jellies, caught in the Loop Current that circulates through the Gulf, broke off the Loop into an eddy south of Alabama and the Florida panhandle. Satellite imagery from the Naval Research Laboratory at the Stennis Space Center confirms this. At the present time the jellies seem to have taken up residence and spread out across the Mississippi Sound to the west side of the Mississippi River.

Whether they can survive and become a new permanent resident to the northern Gulf is a big question waiting to be answered.

"If they do survive the winter, next year the problems they cause will be much more serious then we are seeing now," predicts Graham. "These jellies and their effect on the Gulf's environment and commercial fisheries could be one of the area's biggest problems next year."


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