MOUNT DESERT, Maine — The Maine shoreline, which stretches for thousands of miles up and down tidal rivers, around islands and along peninsulas, beaches and bays, is known for the relatively pristine habitat it provides to countless millions of sea creatures and plants.

But that hasn’t stopped one businessman from trying to make it a little bit better.

The hundreds of harbors that stretch along the Maine coast may be where people have the most immediate effect on the ocean bottom. Harbors are dredged every so often to help keep them navigable. Heavy boat moorings, usually large granite blocks with a metal bar loop protruding from the top, dot the bottom and periodically are raised and lowered as they are repaired or moved to make room for others.

The main purpose of most moorings is to provide mariners with a secure place to tie their boats when they go ashore, but Stewart Hardison thinks they should have a dual purpose. Hardison, the primary owner of Habitat Mooring Systems in Hampden, believes moorings also should double as microcosms of Maine’s coastal marine habitat.

The firm makes moorings from large blocks of molded concrete with holes of varying sizes that run from one side of the mooring to the other. Granite moorings tend to be solid blocks without any holes, Hardison said, but the holes in his moorings provide shelter to a wide array of marine animals, including lobster and cod.

“It’s not enhancing what it is doing,” Hardison said of traditional granite block moorings. “Ours does.”

Habitat Mooring Systems has sold “dozens” of concrete moorings that are in the water between Connecticut and Maine, Hardison said Tuesday. But only two of the moorings are being studied by University of Maine researchers to verify what kind of effect they have on the marine habitat. UMaine and HMS have a close relationship. HMS donates part of its proceeds to the university’s Lobster Institute, and UMaine marine biology professor Ian Bricknell serves as chief scientific officer for the Hampden company.

One mooring being researched is in Sand Cove in South Bristol and the other is submerged in Seal Harbor off Mount Desert Island. On Tuesday, UMaine graduate student Chris Roy and Mount Desert harbor master Shawn Murphy went out to the mooring in Seal Harbor, which anchors the harbor’s “no-wake” buoy, so Murphy could don a scuba tank and dive to the bottom and inspect it. Murphy has been helping out with dives at the buoy site in exchange for the town getting a mooring from HMS at no charge.

The evidence — photos and video of marine plants covering the concrete and animals hiding inside — show that the moorings can provide shelter to marine life that prefers shallow water, according to people involved with the project. Murphy said he has taken several dives to inspect the Seal Harbor mooring, which was first deployed in the harbor in 2010. It has changed from looking like a large cinder block to looking like a small, plant-covered reef, he said.

“We’ve noticed more and more species coming and utilizing that as habitat,” Murphy said Tuesday morning after his dive. “Ever since day one, up until now, there’s been more species there, at different times of the year, obviously. Some times of the year, there’s a bunch of lobster and crab and fish.”

Chris Roy, a UMaine graduate student who has been collecting data on marine life on the concrete moorings, said two sets of circular holes have diameters of 2 inches and 3 inches while the bottom-most, rectangular holes are 3 inches high and 6 inches wide. The largest holes, he said, have attracted lobsters as big as 2 pounds. Cod, cunners, sculpin, shrimp, mussels, clams, multiple types of crabs, sea cucumbers and scallops also have turned up in the moorings.

Roy said the holes sometimes get clogged with silt from turbulent weather, but usually they don’t stay clogged for long.

“Lobsters will clear them out,” he said, adding that natural currents often do the same.

Bricknell acknowledged there is no shortage of marine habitat along the Maine coast as a whole, but said that most harbors have a sandy or muddy bottom, neither of which encourages a lot of biodiversity. Any large, heavy object has an adverse impact on whatever habitat it lands on, he said, but the concrete moorings are better suited for getting sea life to return to where it lands.

Granite is like glass and, unlike concrete, is not an easy material for marine plants to attach to, he said, though it does attract some species such as crabs and starfish. The concrete blocks, however, attract marine plants, which then attract small marine organisms such as shrimp, which, in turn, attract larger ones.

“There are well over 50 species we’ve seen on these moorings,” Bricknell said.

Not only do they enhance the harbor habitat, he said, but they also help raise awareness by boat owners about the proximity of sea life. Bricknell said he has heard from mooring owners who have bought underwater cameras that they attach to poles and lower beneath their boats to see what might be living in their mooring.

Data collected during inspection dives show that between three and five lobsters are living in each mooring’s tunnels during the summer, when many lobsters migrate to shallow water, he said.

“Some people are very protective of the animals on their habitat moorings,” Bricknell said.

The reeflike quality of the moorings is not the only bonus they provide, according to Hardison. They weigh more than 4,000 pounds, more than many granite moorings, and are cheaper to buy and easier to maintain, too, he said.

With each habitat mooring, a chain hangs down from a surface buoy and is connected to the block with a removable metal rod that locks in place through the center of the mooring.

The rods slide through a link in the chain to keep it in place and are easily replaceable, Hardison said. Metal loops or “staples” in a granite block are not so easy to replace when they eventually corrode in the salt water, he added.

A granite mooring can run more than $1,200, Hardison said, while an HMS mooring costs less than $900.

Murphy, the harbor master, said that he has had boat owners ask him about the concrete habitat moorings. He said there are roughly 300 moorings in Northeast Harbor, most of which, if not all, are traditional granite blocks. Northeast Harbor, where Murphy’s office is located, attracts a lot of large, recreational boat traffic from late spring through early fall.

“A lot of people express interest in the idea,” Murphy said.

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Bill Trotter

A news reporter in coastal Maine for more than 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors....