Bulkhead Blitz Keeps Jellyfish Population at Bay

By Lauren Wanko

The morning sun beamed down on the Barnegat Bay as bulkheads and docks were scrubbed clean of sea nettle polyps.

“Sea nettles are jellyfish that have taken up residency in the Barnegat Bay,” said Paul Bologna. “It’s really happening over the last decade or so that the numbers have really increased.”

A polyp is one of the smallest life stages of a jelly fish. They need hard substrates like docks and bulkheads to survive. These polyps clone themselves and eventually generate adult jellyfish, says Montclair State University’s Dr. Bologna. He’s teamed up with the Department of Environmental Protection for their first Barnegat Bay Bulkhead Blitz in an effort to demonstrate the steps homeowners can take to reduce sea nettle populations. The agency says periodically scrubbing or power-washing the microscopic polyps can keep the population in check.

“It’s smart for them to consider doing this in the fall right when they’re wrapping up for the season. It’s a thick, thistle brush, no different, you can buy it at Home Depot or Lowes,” said the DEP’s Dan Kennedy.

Kennedy says sea nettles can create ecological imbalance.

“They’ll jump on top of the food chain pretty quickly and they will knock out other species that people like to fish,” he said.

The newer bulkhead and dock materials, like metal and plastic, have created an ideal environment for sea nettle polyps to thrive.

“It’s not toxic so they don’t have to worry about that,” Dr. Bologna said.

Sea nettle polyps can also settle under jet ski ramps.

“Most people take them out in the fall time,” Kennedy said. “But some people leave them around year round, so our recommendation is try to pull them out to lessen the breeding grounds.”

The scrubbing disrupts the life cycle of the polyps by dislodging them, says Bologna.

“So if there’s some way we can disrupt that population of polyps then you shouldn’t have as many jellyfish the following year because you kind of cut down on the numbers to begin with,” he said.

Over the years Dr. Bologna and his team have swabbed floating docks and bulkheads to analyze for the presence of sea nettle DNA. He says they’ve identified that DNA in dozens of lagoon systems in the Barnegat Bay. The MSU team has also measured the amount of polyps that have grown on settling plates off docks and bulkheads in the bay.

“Some of the highest densities that we get are on the order of between 8 and as high as 30,000 little polyps per square yard, or per square meter as we scale them up, so they can be unbelievably abundant,” Dr. Bologna said.

The DEP and Bologna hope to revisit these sites in the spring and compare the cleaned docks and bulkheads to areas that weren’t scrubbed