Fishing trawlers, seaweed farming, and tourism on the coasts of Kenya and Tanzania are threatening the survival of seagrasses, warns the United Nations Environment Programme (Unep).

Now, Unep wants countries to include seagrass protection and restoration in their nationally determined contributions to help reduce the amount of heat-trapping carbon in the atmosphere.

In its new report titled Out of the blue: The value of seagrasses to the environment and to people, launched on World Oceans Day on June 8, Unep blames these unsustainable activities for a deteriorating coastal ecosystem, a decline in coastal productivity, and affected certain supportive functions performed by the marine plant leading up to loss of critical fisheries habitat.

Known as the “lungs of the sea” due to their role in producing oxygen in the water, the flowering plants that grow entirely underwater perform numerous functions, including stabilising the sea bottom, providing food and habitat for other marine life, and provide numerous other services to coastal communities. East Africa’s coast has 12 known seagrass species.

Seagrass ecosystems are biologically rich and highly productive, providing valuable nursery habitats to more than 20 per cent of the world’s largest 25 fisheries and filtering pathogens, bacteria, and pollution out of seawater.

“The Out of the Blue report showcases the many ways that seagrasses help people thrive and sustain the healthy natural environment that we all depend on,” said Dr Maria Potouroglou, seagrass scientist at Grid-Arendal and lead editor of the report.

For example, it is estimated that seagrasses covering an area of seven square kilometres of Gazi Bay at the Diani-Chale Marine National Reserve, Kenya, comprise of a total carbon stock of 620,000 Mg, with a monetary value estimated at $19 million in regulated global climate at a global scale.

This value is unevenly shared across the globe with China, Europe and the US as the main beneficiaries.

Though Seagrass meadows cover only 0.1 per cent of the ocean floor, they are efficient carbon sinks, storing up to 18 per cent of the world’s oceanic carbon.

“Seagrasses can help us solve our biggest environmental challenges. They purify water, they protect us from storms, they provide food to hundreds of millions of people, they support rich biodiversity, and they efficiently store carbon.”, said Ronald Jumeau, Permanent Representative to the United Nations and ambassador for Climate Change, Seychelles.

UNEP said new data suggest that seagrasses are among the least protected coastal habitats. Only 26 per cent of recorded seagrass meadows fall within Marine Protected Areas compared with 40 per cent of coral reefs and 43 per cent of mangroves.

The Unep World Conservation Monitoring Centre, said it had found in its most recent census that an estimated seven percent of seagrass habitat is being lost worldwide each year.

That is close to a football field of seagrass lost every 30 minutes.

The survey also found at least 72 seagrass species in decline around the world. Since the late 19th century, almost 30 per cent of known seagrass area across the globe has been lost. The main threats to seagrass meadows include urban, industrial, and agricultural run-off, coastal development, dredging, unregulated fishing and boating activities, and climate change.

Yet, seagrass beds in the region, according to the UNEP support sizeable populations of two endangered species, the greenturtle, the Dugongdugon and seahorses, both of which feed on seagrasses.

They act as nursery, breeding and feeding grounds for marine fish and crustacean species of economic importance such as shrimps and spiny lobster.