Overlooked Seagrasses Vanishing, New Atlas Shows

LONDON, UK, October 15, 2003 (ENS) - The first global survey of the underwater seagrass meadows that border the world's coasts reveals that 15 percent of this marine ecosystem has been lost in the last 10 years. The importance of seagrass has not previously been recognized, but researchers who compiled "The World Atlas of Seagrasses" say these true flowering plants shelter fish, turtles and endangered mammals and play a critical role in climatic and oceanic carbon cycles and in coastal protection.

"The World Atlas of Seagrasses," prepared by the United Nations Environment Programme World Conservation Monitoring Centre (UNEP-WCMC) provides the a global estimate for seagrasses worldwide. They cover 177,000 square kilometers, an area two-thirds the size of the UK, an underestimate, say the atlas authors, as the western coasts of Africa and South America have not been surveyed.

The new atlas puts seagrass beds on to the map for the first time. Fifty-eight authors were involved in writing the chapters and completely new data sets have been created, with records compiled from 520 sources and 120 countries.

"We now have a global, scientific view of where seagrasses occur and what is happening to them," said Klaus Toepfer, UNEP executive director. "Unfortunately, the scientists have presented us with a worrying story. In many cases, these vitally important undersea meadows are being needlessly destroyed for short-term gain without a true understanding of their significance."

Healthy seagrasses in the Florida Keys National Marine Sanctuary (Photo by Heather Dine courtesy NOAA)

Seagrasses are a mixed group of true flowering plants - not seaweed - that grow submerged in large meadows in both tropical and temperate seas. They are a functional group of about 60 species of underwater marine flowering plants.

Thousands more associated marine plant and animal species make use of seagrass habitats. They range from the blades of eelgrass in the Sea of Japan, at more than 12 feet long, to the tiny, inch-long, rounded leaves of sea vine in Brazilian tropical waters.

"Seagrasses are quite possibly the most widespread shallow marine ecosystems in the world. " Yet," says Ed Green, one of the co-editors of the Atlas, "there are few places where seagrass meadows are protected. The importance of seagrass has not previously been recognised."

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

"Seagrass beds have been needlessly destroyed for short-term gain without real analysis of the values that the intact ecosystems bring to coastal society," said Mark Collins, director of UNEP-WCMC.

"Physically they protect coastlines from the erosive impact of waves and tides, chemically they play a key role in nutrient cycles for fisheries and biologically they provide habitat for fish, shellfish and priority ecotourism icons like the dugong, manatee and green turtle," Collins said.

Atlas co-editor Frederick Short of the University of New Hampshire, said, "Seagrasses are a critical and threatened coastal habitat worldwide. Their role in the ecology of the ocean and their importance to fisheries is increasingly recognized. The World Atlas of Seagrasses makes available a global perspective on this imperiled ecosystem."

"Like coral reefs, seagrasses are at a critical juncture, heavily impacted by human activities and climate change," said Short. "With the global view provided by the atlas, our ability to preserve and restore seagrass ecosystems is enhanced."

In 2002, the World Summit on Sustainable Development (WSSD) meeting in Johannesburg, South Africa, adopted a commitment to reverse the trend of losses by 2010, said Toepfer. "To achieve this we need hard facts on which to base decisions. The World Atlas of Seagrasses meets that need for a vital marine ecosystem whose importance has largely been overlooked until now."

Conservationists view the atlas as the first step towards an essential Global Marine Assessment, another key objective of the WSSD.

"The public can play an important role," said Collins. "By insisting on protection for sea horses, turtles and dugongs they will also safeguard the ecosystem that supports them and has intrinsic benefits that are less obvious."

Sponsoring organizations that contributed to the production of the atlas include: DEFRA, DFID, UNEP DEWA, The David and Lucile Packard Foundation, Ramsar Convention on Wetlands, International Coral Reef Action Network, University of New Hampshire, World Seagrass Association, Scientific Committee on Oceanic Research, Estuarine Research Federation.

For more information about the Atlas, including maps and photographs go to http://www.unep-wcmc.org/marine/seagrassatlas/ or http://www.unep.org

The World Atlas of Seagrasses is available from: http://www.ucpress.edu/books/pages/10168.html