‘Seahorse hotels’ to anchor new Southold coastal restoration project - North Fork Sun

Back in the 1970s and early 1980s, the Peconic Estuary pulsed with life — oyster reefs flourished, scallops and clams blanketed the bay bottoms and meadows of eelgrass rippled like green silk beneath the waves. But over time, a slow unraveling began. Overharvesting, declining water quality and the relentless push of coastal development and dredging devastated Eastern Long Island’s once-thriving marine ecosystems.

For the past decade, the Cornell Cooperative Extension Marine Program’s “Back to the Bays” initiative has been working slowly but steadily to weave the estuary back together — one stewardship site at a time. Last week, they unveiled the foundation of their latest site at Cedar Beach Creek in Southold, a project in partnership with the North Fork Polar Bears cold plunge club.

At a May 7 workshop at Cedar Beach, Back to the Bays aquaculture specialist and stewardship site manager Kate Rossi-Snook described the bigger picture — a future stitched together by dozens of strategically-chosen restoration zones throughout the East End estuary.

“We believe that getting your feet wet and your hands dirty and understanding exactly what we’re doing and how we’re doing it — that’s how you get real community buy in, and that’s where you see success.”

At Cedar Beach and other stewardship sites across the East End, volunteers and marine restoration specialists have joined forces to breathe life back into the bay: planting eelgrass beds, seeding countless millions of oyster, scallop and clam larvae, and — in a new twist this spring— building underwater “hotels” for northern lined seahorses, an enchanting and essential native species.

The hands-on efforts are part of a broader coastal revival movement in recent years that aims to demonstrate that targeted restoration efforts, supported by scientific research and community engagement, can lead to significant ecological improvements in coastal habitats.

“Smothered”

Rossi-Snook remembers the estuary before the tides turned — when marine life thrived and baymen hauled in bounties. Then came the brown tide blooms in 1985, creeping in and out of the estuary for years, annihilating scallop grounds that once fed generations.

“Increased development, with the hardening of shorelines and filling in of the marshes, disrupted the area’s ecological processes,” she said last week. “Excess nutrients entering the creeks and harbors from cesspools and fertilizers literally fed the blooms of harmful algae that smothered the eelgrass meadows, shellfish beds and finfish populations.”

At stewardship sites like Cedar Beach, the mission is to restore and carefully monitor eelgrass beds — the region’s dominant seagrass and among the most biodiverse habitats in our coastal waters. These meadows not only buffer the shoreline from erosion, but they trap excess nutrients, store carbon and help cool the sting of climate change.

They are also the crucial shellfish sanctuaries for oysters and clams — bivalves that filter the water, recycle nutrients, and make way for light to reach the seabed. One oyster, a humble sentinel of the estuary, can filter up to 50 gallons of water a day.

Wild oyster larvae favor hard places to call home — rocks, shells, reefs — while clams burrow down into sandy beds with clean water flow. So restoring eelgrass beds, salt marshes, tidal flats and oyster reefs are all key components of coastal restoration. 

‘Conditioning’

To bring millions of oyster larvae into being, Back to the Bays collects thousands of pounds of discarded shells from local seafood restaurants. The larvae are naturally drawn to these shells — a familiar cradle from generations past.

Shelter Island restaurants Salt and The Chequit, Greenport’s Silver Sands, Cowfish in Hampton Bays and Fauna in Westhampton Beach all participate in the program by donating their used shells, Rossi-Snook said.

The shells are piled and left to cure in the open air for six to twelve months, scrubbing away any lingering matter before becoming nurseries for the next generation.

The oysters are nurtured on a rich diet of algae for six to eight weeks, and then, with great care, coaxed into spawning.

“It’s called conditioning,” she said. “We gradually increase the water temperature over the course of time — and we trick them into thinking it’s spring. On spawn day, we take them out, put them in a shallow tray and fluctuate the water temperature up and down, mimicking the tidal cycle because that’s what triggers their spawning: the temperature and food availability.”

Boosting their numbers in this way, she explained, is a practical necessity.

“If you think about what would be required to have all of these adults in one area to then spawn at the same time and have this concentration of larvae out in the wild — it’s not likely. So this is to kind of give them that population boost.”

At a workshop last week, Rossi-Snook pointed to a photo of a bare patch of bay in Coecles Harbor off Shelter Island from 2022. “If you were a fish being pursued by a predator, how would you get away here?” she said. “It’s like a desert. There’s nowhere to hide … There’s almost no life here that even is supporting multiple species of macro algae, which — like eelgrass — returns oxygen to the water column.”

Today, that same spot is teeming with life: grass shrimp, eels, pipe fish, black sea bass and black fish have all returned to the sheltering folds of the restored reef.

A scallop flex.

Seahorse ‘hotels’

The clam seeding process, meanwhile, begins in mesh-bottom barrels, where ‘post set’ clams which have completed their larval stage are shielded from predators and nourished by seawater pumped continuously up through their tiny world.

“So, they’re getting lots of food, but they’re getting all that seawater pumped through them,” Rossi-Snook said.

When the baby clams reach about the size of a fingernail — 10 to 13 millimeters — they’re strong enough to be planted in the wild.

This year brings a more whimsical but vital addition to the restoration repertoire: seahorse hotels, which are essentially repurposed acquaculture cages that can remain in place year after year so the seahorses can check back in each spawning season.

Northern lined seahorses are creatures of both habit and memory.

“Meaning they come back every year where they were born and where they’ve made it the previous year,” she explained. “So if they lose that cage, which they think is their habitat, they’re confused. They need to start over. So we’re trying to offer these artificial habitats in places where we’ve had reports of seahorses being, but where eelgrass won’t necessarily grow.”