More jellyfish in Cape Cod waters? Science teacher examines flowers
Check out the moon jellyfish in Channel Islands Harbor
Check out the moon jellyfish at Channel Islands Harbor in Oxnard. Photos by Mike and Bonnie Mercadante.
WENDY LEUNG/THE STAR, WENDY LEUNG/THE STAR
MASHPEE – Since Nicole Corbett was hospitalized after becoming entangled in a stinging nettle six years ago, she has noticed an increasing number of these jellyfish in the south-facing waters of Cape Cod.
In fact, so many of them have already appeared that she now wonders: “Could breeding grounds for nettle jellyfish be forming in this area?”
Now Corbett, president and CEO of the Popponesset Water Stewardship Alliance — a nonprofit that uses citizen-led research and education to address environmental problems in coastal Nantucket Sound — is leading a scientific study to find out.
“On the south side of Cape Cod, we have had problems with jellyfish blooms for the past decade,” she said during a recent visit to Ockway Bay Dock, one of the study sites.
Corbett is a high school science teacher.
“One of the species that contributes to this is the Atlantic nettle,” she said.
Warmer water brings warmer nettles
Stinging nettles are usually associated with the mid-Atlantic. As the waters warm, she explained, they are migrating up the coast, including into the warming bays on the south side of the Cape. She has also documented more frequent and larger swarms of native moon jellyfish, some of which are up to 30 centimeters across.
She said that this is “probably the northernmost range of stinging nettles at this time. I have not heard any reports of them in northern Cape Cod yet.”
She noted that calmer waters in warm bays such as Falmouth, Mashpee and Barnstable are more likely locations for nettle breeding sites to establish.
When adult jellyfish mate, they release eggs that float until they stick to hard surfaces like the bottom of docks, where they then form polyps – “very, very small, anemone-like organisms.” If conditions are right, they enter the next stage of life, are released into the water and develop into adult jellyfish, and then the cycle starts again.
To make matters worse, the polyps can also clone themselves asexually on a hardened substrate.
Do docks serve as breeding grounds for jellyfish?
The theory is that residential and communal moorings in the Cape’s bays serve as a basis for regional nettle farming, leading to an increase in the jellyfish population and the establishment of a local (rather than a migratory) population.
Corbett noted that Paul Bologna, director of the marine biology and coastal sciences program at Montclair State University in New Jersey, has been leading research on stinging jellyfish since the mid-2010s. He was the first to theorize that floating docks could be a factor in hard-surfacing bays, increasing the breeding grounds of these jellyfish.
The polyps, Corbett said, “like protected surfaces. The bottom of a dock is a really good surface if you’re a polyp trying to hide.”
She modeled her organization’s study on Bologna’s research, which involves hanging rows of “drop plates” — 10 in total — in the water at various docks. In addition to the dock at Ockway Bay, there are plates at the Mashpee Neck Marina and at private docks volunteered for the program in Shoestring Bay and along New Seabury and Popponesset Island.
Corbett’s team, with help from Alliance Treasurer Bob Wittstein, made settling plates out of ground Plexiglas to mimic the underside of docks. Corbett also made some out of scallop shells.
“We’re trying to compare artificial and natural substrates to see if there’s a difference,” Corbett said.
If you find a lot of nettle eggs on the plates, “that would be a good indication that they are also sticking to the underside of the dock,” she said.
In New Jersey’s Barnegat Bay, where stinging nettles have proliferated, Bologna’s team found polyps under docks. In response, the organization Save Barnegat Bay launched a pressure-cleaning program to reduce the numbers.
“If we start to push back the polyps, we may be able to start to push back the stinging nettle population,” Corbett said.
Without that control, communities could experience “big boom years” where the nettle population gets very, very large, she said. “Then it just becomes harmful to people who are recreationally in the water.”
Nettles on the southern beaches of the Cape
On Cape Cod, the nettles have been showing up in large numbers on south-facing beaches around the second week of August, which Corbett says happens “pretty much every year at this point.” Some years, like 2021 and 2023, there have been huge numbers. Other years, there haven’t been as many. So far, this year seems to be off to a slow start, but August is only halfway over.
Aside from their presence on beaches, jellyfish can also pose a problem when they enter areas with heavy boat traffic.
“They get torn apart and the tentacles are swimming around and they still sting people,” Corbett said. “You get stung and you’re like, ‘What’s stinging me?’ and then there’s a little tentacle that looks like a violin string wrapped around you and you’re trying to find it. It’s pretty horrific.”
Moon jellyfish
Corbett and her team are studying the increasing and large swarms of moon jellyfish in local waters. In particular, she wants to find out if the moon jellyfish in Nantucket Sound have evolved the ability to sting easily. The jellyfish are not known to sting, but there have been reports of stings.
“We’re actually doing a study this year with the University of California, Merced,” she said. “We have 20 research facilities, including mine, looking for moon jellyfish all over the East Coast and trying to genetically code them all to see if there are genetic differences in the moon jellyfish at different locations.”
Heather McCarron writes about climate change, the environment, energy, science and the outdoors. You can reach her at [email protected].
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