Plum Island Divers Report on An Unspoiled Ecosystem

Divers who spent a week last August exploring the underwater lands surrounding Plum Island are still excited by the pristine conditions they found during their research.

Scientific divers from InnerSpace Scientific Diving in Albany, working for a New York Natural Heritage Program project funded by several private donors through Save the Sound, presented the results of their research in a Zoom forum organized by Save the Sound March 31.

Over the course of 26 dives, the crew found 126 species of plants and animals, many of them in a rocky area on the north side of the island that they explored on their final day.

Plum Island, off the tip of Orient Point on the North Fork, is owned by the federal government. It is home to the Plum Island Animal Disease Center, which is slated to be replaced this year by the new National Bio and Agro-Defense Facility in Manhattan, Kansas, after which the Department of Homeland Security is slated to dispose of the island. Save the Sound is coordinating a group of 120 environmental and community groups, the Preserve Plum Island Coalition, working on a preservation future for the island.

“That last dive was fantastic for us. There was so much packed in that area,” said Steve Resler of InnerSpace Scientific Diving, who led the dive. “There were lined anemones that numbered in the thousands on the sides of boulders. If I were to go back, I would want to go back to that area and spend more time there.”

“It’s a relatively undisturbed marine ecosystem. In our part of the world, that’s not common,” said NYNHP Chief Zoologist Matt Schlesinger.

A lined anemone. |. Innerspace Scientific Diving

Mr. Resler said the divers didn’t find a single piece of trash — “not a bottle cap, not a fishing line” — over the course of the dive, a rare event in this part of the world.

“Some of these habitats are rare — we have eelgrass, rocky intertidal areas and subtidal areas with large boulders,” said Dr. Meaghan McCormack, a marine zoologist with the New York Natural Heritage Areas Program who catalogued the samples collected by the divers. “For one small island to have these natural communities surrounding it is really special.”

What’s also rare is Plum Island’s coastline, which has no hardened structures, enabling natural erosion and accretion of sand along the beaches and bluffs surounding the entire island.

“It’s nine miles of untrammeled coastal system,” said Curt Johnson, president of Save the Sound, which helped organize the dive. “Erosional and accretional features work together. This is a system that all works together.”

“If it erodes, that’s not a bad thing — what’s bad is what we put in beach areas when the beaches have to move. Then we have a problem,” said Mr. Resler. “That’s my view as a former coastal manager.”

The divers began their work on the east side of the island, on a sandy transect, after which, a little farther east, they found larger boulders where gray seals were hauling out, cutting their surveys short. Seals can be aggressive and humans are prohibited by the Marine Mammal Protection Act from getting too close to them.

Divers from Innerspace Scientific Diving
Divers from InnerSpace Scientific Diving at the August 2021 dive.

On the west side of the island, said Dr. McCormack, the divers found eelgrass beds filled with invertebrates, while on the north shore they found anemones and bryozoans, starfish and northern star corals and many, many juvenile fish in the midst of areas of large boulders.

“We only found eelgrass on the western area, at shallower depths,” she added. “Red algae was all over, and we saw mostly kelp in the same areas we saw large boulders.”

She said that, now that the data is compiled, scientists can look at the percentages of plants and animals present in different areas to define the natural communities present in different areas surrounding the island.

But the lure of the final area they studied has the divers excited for further research.

On the last dive, “there was just so much there, and it was so dense,” said Mr. Resler. “We didn’t do as much detailed work there as we’d like to have, because it was the last dive of the week.”

“Bryozoans are on every hard substrate, everywhere,” he said. “They look like plants, but they are not… They are, to me, the greatest influencers here. They provide cover for all manner of fish and other species. We found anthropods, a skeleton shrimp, that looks like a shrimp but with very long appendages. It’s very freaky looking. We found polychaete annelids, worms, that were everywhere, in all the sediments and growing on all rocks…. There were sea stars walking across the bottom, very slow, with hundreds of tiny feet on each arm. If we had done more sampling in the sediment, we would have come back with a lot more.”

Here’s the divers’ report.

Beth Young

Beth Young built her first boat out of driftwood tied together with phragmites behind her family’s apartment above the old Mill Creek Inn in Southold. Nowadays, she spends most of her time kayaking, learning about shellfish, writing newspaper stories, trying to sail a Sunfish, and watching the way the bay changes from day to day. You can send her a message at

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