New carbon-capturing seagrass areas discovered along Irish coast

Role of seagrass in protecting biodiversity is being recognised, but more protections needed, says Coastwatch

A year-long survey of the Irish coastline has verified the presence of 76 large seagrass beds, which play a significant role in capturing significant quantities of carbon and in sustaining rich marine habitats.

Many of the seagrass areas were newly discovered, while a further 21 sites are due to be verified, said Karin Dubsky, a director of Coastwatch, which led the research.

The importance of seagrass in protecting biodiversity and capturing “blue carbon” is being increasingly recognised, though she said there was an urgent need to map their location in Ireland to ensure they were adequately protected.

“Seagrass must be known, respected, monitored and protected to ensure it can play its full role of tackling the biodiversity and climate crises.”

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Ms Dubsky highlighted an issue of poor public knowledge, saying “most people cannot tell opportunistic green seaweed from seagrass” in intertidal areas, while accidental damage from human activities was widespread.

The potential avoided emissions for Ireland as a result of seagrass conservation is 2.2 million tonnes of carbon dioxide but seagrass is being lost at a rate of 1.5-2.5 per cent a year globally. Seagrass beds are found in 14 Irish bays and inlets that are designated Natura 2000 sites, but the report found “half of these sites failed to maintain or reach ‘favourable conservation status’ ”.

Ms Dubsky called for seagrass protection under the Maritime Area Planning Act and in designated marine area plans to be put in place by local authorities when they soon take over responsibility for near-shore areas. Blue carbon also needs to be measured and included in Ireland’s climate commitments known as national determined contributions, Ms Dubsky added.

Coastwatch surveyor Rita Hagan said Dublin was very lucky to have extensive seagrass beds so close at Merrion Strand, which is in a special area of conservation and an important feeding ground for brent geese.

However, she said the beds had declined in size from 18,000sq m-10,600sq m since 2019 and were facing numerous threats. These include invasive seaweeds and ectocarpus algae; heat stress; polluted freshwater streams nearby; and trampling — especially from motorbikes, horses and bicycles.

Desk exercise

Dolf D’Hondt, Coastwatch co-ordinator for west Cork, expressed reservations about the regulatory role of the new Marine Area Regulatory Authority, as he understood “it will be a desk exercise and there won’t be any physical presence on the water”.

Social Democrats councillor for Fingal Joan Hopkins said she was worried about lack of funding for local authorities in taking on new responsibilities, including where there is already protected area status. Her local authority had a comprehensive biodiversity plan but it was only being partially funded, she added.

Bernie Connolly of Cork Environmental Forum, which co-ordinates Coastwatch surveys in Co Cork, raised concern about increasing levels of pollution from excess nutrients in coastal areas arising from agricultural run-off and huge amounts of aquaculture waste, “90 per cent of which ends up on the sea floor”.

She cited the situation in Clonakilty, where algae were exploiting the eutrophic conditions caused by excessive nitrogen and phosphate levels in the water and suppressing seagrass. Exacerbated by increasing warming, the problem was getting increasingly worse, she said, while there was a fixation on putting in place buffer zones on land, including trees but this was not protecting coastal zones, she said. In her view, seepage is the main culprit. “It’s a big problem and is not being addressed.”

Minister for the Environment Eamon Ryan said citizen science was set to play a critical role in restoring and protecting the environment, especially biodiversity. This would be done through increasing the body of knowledge and in improved monitoring and management of locations with backing from local communities; “in protecting what we have”, he said.

As a consequence, Mr Ryan said, his department would make every effort to increase support for citizen science. He agreed with Coastwatch that “if it’s not measured, recorded and looked at, then it could be forgotten. We won’t see what’s happening. We won’t be able to restore it.”

Nature restoration was now a big priority at legislative level in Europe and internationally, Mr Ryan said, with an acceptance that “it has to be given the same prominence that we give the climate COP because it’s all connected”. This was reflected in the importance of seagrass in capturing carbon and sustaining species, he said.

Kevin O'Sullivan

Kevin O'Sullivan

Kevin O'Sullivan is Environment and Science Editor and former editor of The Irish Times