Bountiful seagrasses under threat

By MICHAEL McCARTHY in London

They are the meadows of the sea, beautiful and bountiful but, hardly known and unappreciated, they face increasing threats.

They are the beds of seagrass which fringe many of the world's coastlines, providing rich feeding grounds and shelter for huge numbers of fish and other marine species, including some of the most endangered, such as dugongs and manatees, seahorses and green turtles.

The world's first survey of seagrasses shows 15 per cent of this unique marine ecosystem has been lost in the past decade and conservationists are hoping the findings will prompt Governments and policymakers to prevent further losses.

Seagrass beds are being destroyed by nutrient enrichment from human sewage, from heavy fishing activities, and even by yachting and jet-skiing, say the editors of the World Atlas of Seagrasses, produced by the Cambridge-based World Conservation Monitoring Centre in conjunction with the United Nations Environment Programme.

Dr Ed Green of the centre and Professor Fred Short of the University of New Hampshire pointed out at the atlas launch last week that unlike coral reefs and mangrove swamps - two associated habitats which, in some cases, are protected - seagrass beds are largely taken for granted.

"Seagrasses are quite possibly the most widespread shallow marine ecosystems in the world, yet there are few places where seagrass meadows are protected," Dr Green said.

The atlas, the work of more than 50 authors, estimates that the extent of seagrasses world-wide is 177,000sq m, an area two-thirds the size of the UK.

It suggests seagrass meadows should be considered one of the most important marine ecosystems for humans, playing a vital role in fisheries, protecting coral reefs by binding sediments, cleaning coastal waters and providing coastal defence from erosion.

They are just as important for wildlife, being key habitats for sirenians - the odd-looking sea-cows once mistaken for mermaids.

The dugong is the best-known sirenian. Its relation, the manatee, has three species. All are threatened by habitat loss and the negative impacts of human population growth and development.

They are the only true herbivore marine mammals, and grazing on seagrass is essential for their survival.

Green turtles, one of the most endangered of the seven marine turtle species, are also highly seagrass-dependent.

Seagrasses are a mixed group of about 60 species of true flowering plants (not seaweed) which reproduce sexually and produce pollen.

Thousands of other plant and marine animal species grow submerged in large meadows in both tropical and temperate seas.

- INDEPENDENT