Jellyfish Invasion Threatens Sea Life

Scientists fear millions of Australian spotted jellyfish invading the Gulf of Mexico will threaten coastal sea life from Florida to Louisiana.

“I can’t remember seeing any marine organism in concentration like that,” said Vernon Asper, a marine science professor from Biloxi, Miss., after seeing hundreds of thousands — maybe millions — of the jellyfish while flying over the Mississippi Sound.

“I’ve never seen a school of fish that was that big that had that much biomass. Anything. That’s a large number of anything for the ocean,” he says.

Sea Life, Not Humans, Threatened

The Australian jellyfish, whose largest concentration appears to be around Lake Borgne in Louisiana, aren’t considered dangerous to people.

But the scientists say the density of the animals is dangerous. They’re likely consuming shrimp and oyster larvae, and harvest numbers are down in the Mississippi Sound.

And the jellyfish are large — some as big as 18 inches to 2 feet in diameter.

Harriet Perry of the gulf coast research lab says the creatures, formally known as Phyllorhiza punctata, take up so much space in the sound they could leave smaller sea creatures nowhere to swim.

“Right now is the prime season for blue crab larvae to move from the offshore waters into the sound,” Perry says. “So, they would have to essentially run the gantlet of these jellyfish to make their way into the inshore marshes.”

Hitched Ride Through Canal

The jellyfish are native to Australia and appeared in the Caribbean about 30 years ago. They came through the Panama Canal attached to ships. An unusual current early this summer brought them into the northern part of the Gulf.

Monty Graham, a marine scientist, says the invasion could affect more than creatures of the marsh. He says the jellyfish could easily threaten coastal fisheries, taking away food from young fish and shrimp.

“Jellyfish are voracious predators on the bottom of the food chain,” Graham says. They feed “on the plankton that we’d prefer to go to fish in the Gulf of Mexico. But instead, jellyfish are very good at taking advantage of that food.”

The animals have been thriving in the warm waters, but scientists don’t know how many will survive the winter or at what level the number of jellyfish will stop increasing.

“Big question: Will they survive the winter?” Asper says. “Will they really become the fire ants of the ocean? We don’t know. That’s a big question. And so we’re studying them. With the help from EPA and the Sea Grant we’re talking a look at this. And it’s a big curiosity.”

Steve Phillips of ABC affiliate WLOX-TV in Biloxi, Miss., and The Associated Press contributed to this report.