Environmental groups have warned that a plan to combat erosion at a property near Harrington Sound could damage a unique ecosystem.

A planning application for Palmetto Gardens, submitted this year, proposed remediation works to address undercutting of the cliff face caused by tides and storms.

However, it has garnered a series of objections and calls for an environmental-impact statement to be prepared, citing concern about the Harrington Sound Notch.

In a letter of objection, the Bermuda Audubon Society said that the notch was a deep undercutting of the rock below the high tide level formed by black date mussels and other rock-boring organisms.

The charity said the area was so unique that in 2004 the Bermuda Government proposed that Harrington Sound and the notch be considered a “Ramsar site”, protected under the Ramsar Convention created to conserve wetlands.

It explained: “According to the Ramsar information sheet prepared by the Bermuda Department of Conservation, it is a ‘globally unique feature and probably supports the greatest species diversity of sponges in the wider Caribbean’.

“This is further reiterated in the monograph, Ecology of Harrington Sound, Bermuda, by Martin L.H. Thomas, which states: ‘There seems to be no other example of a structure like the Harrington Sound Notch anywhere in the world.’

“The report goes on to describe the enormous biodiversity of the notch ecosystem that includes clams, sponges, sea anemones, seaweeds and corals.

“The area is not only biodiverse but also biodense with research by Dr Thomas showing 4,000 endolithic clam burrows per square metre of rock.

“The proposed revetments will result in destruction of this unique physical feature and its associated habitats in multiple areas on the site.”

The society said that careful consideration must be given and a comprehensive EIS would be needed to fully assess what impact the project could have and to consider alternatives.

It also raised concerns about risks to the surrounding marine environment and the precedent that could be set by taking action without a long-term plan.

“The shores of Harrington Sound are heavily developed,” the BAS said. “If revetment of the Harrington Sound Notch is considered an acceptable protection measure for this property, then every house on the sound may then wish to pursue a similar shoreline development.

“Given the biological and geological significance of this feature, a thorough assessment should be made of the cumulative impact of such revetments.

“The Department of Planning in collaboration with the Department of Environment and Natural Resources should develop a long-term and comprehensive plan for how this issue will be addressed.

“This would avoid a piecemeal approach to what will be an ongoing problem. They need to consider the changing environment and the potential impacts of climate change.”

In another objection letter, the Bermuda National Trust highlighted the Harrington Sound Notch as a “critically important habitat” and said there was no clear reasoning provided to close off or destroy any portion of the “unique and significant biological and geological feature”.

The charity added: “There has been no environmental impact study carried out to determine the rate of expansion of the notch and justify potentially damaging this rare habitat.

“The applicant should be required to conclusively prove that the stability of buildings is under threat and the need for such work to be carried out.”

The BNT also highlighted that an assessment included in the planning application stated that there was “no immediate risk to the existing residential units”, so there did not appear to be an urgent need to “destroy this beautiful and unique piece of our heritage”.

The Bermuda Environmental and Sustainability Taskforce meanwhile called for a full environmental impact assessment to ensure the project does not harm the environment of the area.

“Given that the engineer’s letter states that ‘there is no immediate risks to the existing residential units’, and especially that there is only an assumption that ‘the extent of erosion will be dramatically reduced’ by the work that is being proposed, we believe that a precautionary approach should be taken and an EIA carried out to reveal any possible risks to the environment of the proposed work,“ BEST said.

The organisation, however, agreed with the suggestion in the application that invasive species and root systems should be removed from the area.