Toxic jellyfish spotted in Edgartown Great Pond

‘The clinger’ is a small jellyfish with a big sting.

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"Clingers," shown here from Farm Pond, have been spotted in Edgartown great pond. – Mary R. Carman

Gonionemus vertens, known as the clinging jellyfish or the clinger — a dangerous, toxic species — has been confirmed to be living in Edgartown Great Pond, according to Emily Reddington, director of science and education at the Great Pond Foundation.

Reddington called the Times Tuesday morning while at the pond to confirm a clinger had been caught and identified.

Two sightings of the clinger occurred off the town landing in Edgartown, according to a report from the Great Pond Foundation.

The Times wrote about the clingers last year, which have been reported in Sengekontacket Pond, Farm Pond, Lake Tashmoo, Stonewall Pond, and Squibnocket Pond, but their recent movement has been cause for alarm for marine scientists.

“It’s become clear to us it’s becoming so abundant that they are tending to move out of eelgrass areas to rest and hang on to something else, such as docks, boats, and oyster aquaculture,” Mary Carman, a research specialist from the Woods Hole Oceanographic Institution (WHOI), told The Times. Carman has been studying invertebrate invasive species on the Island for the past 13 years.

Clinging jellyfish are typically found in low-activity areas where they can cling to eelgrass and seaweed. What is so alarming about their sighting in Edgartown Great Pond is the salinity levels, Carman told The Times. The lowest salinity level thought to be livable for clinging jellyfish was 25 parts per thousand — within the past week, Edgartown Great Pond was measured to be at 19.7 to 20 parts per thousand, she said.

The clinger can be recognized by the orange-brown cross on its see-through body. It gets its name from the sticky pads on the ends of the tentacles.

The stings are known to be severely painful, cause redness at the sting sight, and potentially cause respiratory or neurological problems, according to the WHOI website.

In a published paper last October, Carman said she tried having spider crabs eat the clingers, but discovered the crabs died within 24 hours of eating them.

Carman will be coming to the Island tomorrow to get in the pond and see the clingers for herself. “It seems the species is spreading around and moving,” she said. “This jellyfish thing is very concerning.”
Reddington told the Times the confirmation of the clinger in Edgartown Great Pond is bad news. “I’m not happy to see them. It’s something we don’t want adults dealing with, or children. It’s a hazard in the pond now,” she said.

The next step will be further study of the pond to see how large the clinger population is. The hope is that the clingers may die once the water in the pond rises and the salinity level decreases.