Jellyfish are here early and staying longer, thanks to climate change

An unwelcome visitor is now bobbing in the bays and off the beaches of Delaware, Maryland and Virginia: jellyfish.

Experts say jellyfish season is coming earlier in the year and lasting longer, thanks to warming waters of the Atlantic Ocean. With the increased number of jellyfish, comes the possibility of more stings to swimmers.

Jellyfish arrive as early as May and can stay until September, said Ann Barse, a professor of biology at Salisbury University. The gelatinous, bell-shaped animals are attracted to warmer waters, and they congregate off shore and in inland bays.

While warmer water associated with climate change does not increase the number of jellyfish here each year, it does extend the time the creatures capable of stinging humans remain in the waters where humans play and fish.

Barse said the jellyfish population can be attributed to two things: pollution in the bay and the reduction of oysters in the bays.

"So in the past in the bay, the primary filter feeder is the eastern oyster, whose population has been reduced to a fraction of 1 percent of what it used to be," she said. "The filter feeders would be extracting some of these phytoplankton and zooplankton out of the water, meaning there wouldn’t be as many jellyfish."

They feed on plankton, small fish or other jellyfish, Barse said. They are transported by the natural currents of the ocean, and it is around this time every year that the jelly — as they are referred to by some scientists — arrives in the rivers, bays and the ocean on the Delmarva Peninsula.

Jellyfish typically gather in the waters off Rehoboth Beach in the middle of August and in September, according to Rehoboth Beach Patrol Capt. Kent Buckson. But he said the beach patrol has had some reports of jellyfish already this season.

"We have had a few stings the past week," he said. "We have had a lot of the clear jellies the past week that don't sting (moon jellyfish), and they have kind of saturated the water. We don't have a huge influx of them, which is a good thing."

Why the uptick?

Jellyfish have different biological functions than humans, Australian-based biologist Lisa-ann Gershwin said in an interview with USA Today in 2016. They have no brain, blood, heart or bones.

"Pretty much they're just a bag of goo with a stomach and a really primitive nerve net, and gonads," she said. "That's it."

The increase in plankton, she said, comes from the increase of runoff in the bay from farms and developments.

“What we are doing as a normal part of being human — our waste and our coastal construction and our fishing and our carbon dioxide, all of these things — we are creating a world for jellyfish that they're loving,” Gershwin said. “We are giving them the biggest break of their entire history.”

A jellyfish bloom can contain millions of jellyfish and spread over dozens of miles, she said.

The Delmarva Peninsula is not in a bloom now, said Barse. But blooms are problematic for swimmers and for some ecosystems where huge numbers of the creatures make them a top predator.

“That just bends your mind backwards,” Gershwin said. “You think, ‘Hang on, jellyfish is the top predator? What about fish and sharks and whales?’ It's not that they're eating sharks, but they eat the food that the food of the food of sharks would eat, and so jellyfish are able to cripple an ecosystem at the ankles.”

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In the bay, the most common form of jellyfish is the Atlantic sea nettle, Barse said. They prefer the lower salinity of the bay compared to the ocean.

During the winter months, the lion's mane jellyfish can be found in Delmarva bays, said Harrison Jackson, former education coordinator for Maryland Coastal Bays Program, in a July 2016 column.

"This species is the largest known jellyfish species in the world, with bells as large as 6 to 7 feet across," he wrote in the column. "However, we tend to find smaller versions here in Maryland."

In the ocean, the most common forms of jellyfish are the moon jellyfish and the lion's mane jellyfish, Barse said.

But there's a tropical system moving north in the Atlantic that has the possibility of moving the jellyfish into Delmarva waters.

While it does not appear the storm will make landfall, the storm could stir up the waters and transport jellyfish over wide expanses of ocean, Buckson said.

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"It has happened in the past," he said. "But it can move them out, too."

This season, Buckson has had a few reports of stings.

Although the sting can be uncomfortable, creating a burning sensation on your skin, the common Atlantic sea nettle does not deliver an attack that is considered deadly.

However, there is a jellyfish-type animal that does carry the potential to deliver a lethal sting: the Portuguese man o' war.

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If somebody does get stung by a jellyfish, Buckson said there are many different remedies.

"(Rehoboth Beach Patrol) does a remedy that is half water and half vinegar," he said. "If you have access to your hotel or house, put children in the shower and make the water as hot as they can stand it — that tends to neutralize the pain."

Ice cubes, too, work, Buckson added, because they numb the pain. However, hot water is recommended.

Jackson said applying meat tenderizer can often act as a good antidote, although it does not completely alleviate pain.

"Time works best for most, " he said, "but for severe exposure it is best to see a physician."

Information from USA Today was used in this report.

On Twitter @hughesg19

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