A special sanctuary for seagrass has been created in a lagoon on Ireland Island in an effort to guard a protected habitat from a protected species – green turtles.

Grates have been installed at both marine entrances to the lagoon to protect the area in a partnership between the Department of Environment and Natural Resources and the West End Development Corporation.

Sarah Manuel, a senior marine conservation officer with the DENR, said in the latest edition of the Envirotalk newsletter that seagrass around the island had suffered in recent times.

Dr Manuel added: “Anyone swimming or boating around our Island this summer, is likely to have noticed that a lot of the seagrass beds have disappeared, for example at Admiralty Park and Somerset Long Bay.

“Where there is seagrass, it is very short and no longer providing refuge for juvenile fish, newly settled spiny lobsters and other small animals.”

She said: “The lagoon, with its mangrove-lined edges, is an ideal area to create a seagrass sanctuary.

“Both mangroves and seagrass are important nursery habitat for many of our fish species, including some of our commercially important fish, and numerous other organisms.”

Dr Manuel highlighted that the loss of seagrass could damage coral reefs and commercial fisheries.

She added that human activity had been responsible for at least some of the decline in local seagrass.

She said: “Shoreline development, dredging, ocean dumping, land creation, concrete and floating docks, boat propellers, anchoring, groundings and moorings have all impacted our inshore seagrass beds over the years.

“At Bermuda’s northern latitude, the cooler water temperatures and shorter day lengths in winter limit seagrass growth rates and their ability to recover from any negative impact.”

Dr Manuel said seagrass beds were shelter for young fish, helped prevent harmful algae blooms and could also reduce ocean acidification and climate change by removal of carbon from the water.

Seagrass is also an important food source for green turtles – and the island’s increased migrant green turtle population has caused additional pressure.

Dr Manuel explained that successful conservation efforts in the areas where the turtles nested had helped to bolster the population, which meant more juvenile turtles.

She added: “We have an imbalance in our marine ecosystem where one protected species, the green turtle, is putting grazing pressure on a protected habitat, seagrass beds.

“Sharks are the natural predator of green turtles. In the northwest Atlantic sharks have been overfished and their scarceness in our waters leads to even the weakest sea turtles surviving.

“Add this to the human pressures and we can begin to understand the ecosystem imbalance and need for restoration efforts of both seagrass and sharks.”

Dr Manuel said the lagoon had been full of long seagrass until 2017, but turtles had started to eat in the area as other seagrass beds have disappeared.

She added: “Now the seagrass is so grazed that there are very few shoots remaining.”

Crisson Construction supplied and installed grates at both of the lagoon openings to allow water and fish through – but stop sea turtles.

A total of seven turtles were also removed from the lagoon and moved to the Great Sound.

Dr Manuel said: “Five of the seven were underweight, an indication that they are not finding enough food.

“One of the turtles had a Bermuda Turtle Project tag – It was first tagged in 2011 at Cow Ground Flat, then recaptured by BTP in 2017 at Somerset Long Bay and now in the lagoon.

“Normally, when juvenile green turtles arrive on the Bermuda platform they find a seagrass bed and never swim very far from that particular bed.

“They can stay on their chosen seagrass bed for up to 14 years, and possibly longer.

“It is most likely that this tagged turtle has moved from site to site in search of food.”