An “ecological disaster has unfolded in Bermuda” and stripped the waters of key species, according to a conservation and research group.

The Bermuda Turtle Project warned of “what can only be described as a dramatic crash” in the marine reptiles, along with the underwater habitats that support them.

David Godfrey, executive director of the Sea Turtle Conservancy – which runs the project with the Bermuda Zoological Society – warned: “Large numbers of turtles have disappeared from Bermuda, and many of those observed in the last few years have been severely malnourished,”

The project, tracking juvenile green turtles growing up in Bermuda’s nearshore waters, said news on the animals had been largely “encouraging – until now”.

“Locations all around Bermuda where green turtles once thrived are now completely devoid of turtles – along with the seagrass they depend on to survive.”

The researchers said blaming the turtles for overgrazing their own habitat was incorrect.

They highlighted the influx of humans into Bermuda over the past century, leading to a cascade of pollution.

Dr Gaëlle Roth, BTP co-director, said: “It’s the ecological collapse of seagrass that caused most of the turtles to either depart from Bermuda or die from starvation.”

The group said a surge in population in Bermuda had been “tipping the ecological scales”.

The project highlighted large-scale development has introduced “thousands of septic tanks, waste water discharges, oil and gas runoff, pesticides, cruise ship impacts, motor boats, moorings, incineration of garbage, plastic pollutants, and undocumented levels of nutrient runoff from the island.

“All of which has combined to push Bermuda’s seagrass past the brink.”

Seagrasses form beds and meadows in shallower waters that are vital to the welfare of many of Bermuda’s marine animals – supporting fish, lobsters and shellfish as well as turtles.

The grasses, the sea’s only flowering plants, also help protect coral reefs from sediment.

Dr Godfrey said pointing to sea turtles as the cause of their decline in Bermuda “distracts attention from the real work needed to reduce human impacts on the marine environment”.

“What conservation leaders do next will for ever determine the fate of Bermuda’s most iconic marine species as well as the island’s seagrass and coral reef habitats.”