Loss of coastal seagrass habitat accelerating globally

Jun 29, 2009

An international team of scientists warns that accelerating losses of seagrasses across the globe threaten the immediate health and long-term sustainability of coastal ecosystems. The team has compiled and analyzed the first comprehensive global assessment of seagrass observations and found that 58 percent of world's seagrass meadows are currently declining.

The assessment, published in the , shows an acceleration of annual seagrass loss from less than 1 percent per year before 1940 to 7 percent per year since 1990. Based on more than 215 studies and 1,800 observations dating back to 1879, the assessment shows that seagrasses are disappearing at rates similar to and tropical rainforests.

The team estimates that seagrasses have been disappearing at the rate of 110 square-kilometers (42.4 square-miles) per year since 1980 and cites two primary causes for the decline: direct impacts from coastal development and dredging activities, and indirect impacts of declining water quality.

"A recurring case of 'coastal syndrome' is causing the loss of seagrasses worldwide," said co-author Dr. William Dennison of the University of Maryland Center for Environmental Science. "The combination of growing urban centers, artificially hardened shorelines and declining natural resources has pushed coastal ecosystems out of balance. Globally, we lose a seagrass meadow the size of a soccer field every thirty minutes."

"While the loss of seagrasses in coastal ecosystems is daunting, the rate of this loss is even more so," said co-author Dr. Robert Orth of the Virginia Institute of Marine Science of the College of William and Mary. "With the loss of each meadow, we also lose the ecosystem services they provide to the and relying on these areas for nursery habitat. The consequences of continuing losses also extend far beyond the areas where seagrasses grow, as they export energy in the form of biomass and animals to other ecosystems including marshes and coral reefs."

"With 45 percent of the world's population living on the 5 percent of land adjacent to the coast, pressures on remaining coastal seagrass meadows are extremely intense," said co-author Dr. Tim Carruthers of the University of Maryland Center for Environmental Science. "As more and more people move to coastal areas, conditions only get tougher for seagrass meadows that remain."

Seagrasses profoundly influence the physical, chemical and biological environments of coastal waters. A unique group of submerged flowering plants, seagrasses provide critical habitat for aquatic life, alter water flow and can help mitigate the impact of nutrient and sediment pollution.

More information: The article "Accelerating loss of seagrasses across the globe threatens ," appears in the Proceedings of the National Academy of Sciences Early Edition on June 29. The article was authors by 14 scientists from the United States, Australia and Spain, including Drs. Michelle Waycott (lead author), Carlos Duarte, Tim Carruthers, Bob Orth, Bill Dennison, Suzanne Olyarnik, Ainsley Calladine, Jim Fourqurean, Ken Heck, Randall Hughes, Gary Kendrick, Jud Kenworthy, Fred Short, and Susan Williams.

Source: University of Maryland (news : web)

Explore further: Despite significant reduction in smog-producing toxins, the Greater Toronto Area still violates ozone standards

add to favorites email to friend print save as pdf

Related Stories

Seagrass ecosystems at a 'global crisis'

Dec 01, 2006

An international team of scientists is calling for a targeted global conservation effort to preserve seagrasses and their ecological services for the world’s coastal ecosystems, according to an article published in the ...

Nitrogen retained through loss

May 22, 2008

The nitrogen cycle plays a major role in seagrass fields. Dutch researcher Arie Vonk studied the nitrogen dynamics of seagrasses in Indonesia. He discovered that the interaction between seagrasses, animals and microorganisms ...

The mystery of the missing sea nymph – solved!

Nov 28, 2005

A four-year study into the mysterious and rapid decline of Adelaide's coastal seagrass species – mainly Amphibolis (commonly known as 'sea nymph' or 'wire weed') and Posidonia – is close to completion.

Study: World's seagrass beds are declining

Mar 28, 2006

A University of New Hampshire scientist says the world's seagrass beds -- important habitats, food sources and sediment stabilizers -- are disappearing.

Recommended for you

Water crisis threatens thirsty Sao Paulo

4 hours ago

Sao Paulo is thirsty. A severe drought is hitting Brazil's largest city and thriving economic capital with no end in sight, threatening the municipal water supply to millions of people.

Climate change: meteorologists preparing for the worst

10 hours ago

Intense aerial turbulence, ice storms and scorching heatwaves, huge ocean waves—the world's climate experts forecast apocalyptic weather over the coming decades at a conference in Montreal that ended Thursday.

Sunlight, not microbes, key to CO2 in Arctic

10 hours ago

The vast reservoir of carbon stored in Arctic permafrost is gradually being converted to carbon dioxide (CO2) after entering the freshwater system in a process thought to be controlled largely by microbial ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

omatumr
not rated yet Jul 03, 2009
ONLY 15% OF SEAGRASS REMAINS ?

This study supposedly "shows an acceleration of annual seagrass loss from less than 1 percent per year before 1940 to 7 percent per year since 1990."

The fraction of seagrass remaining is only (0.99)^50 x (0.93)^19 = 0.60 x 0.25 = 0.15 = 15%.

Apparently the research funds available for seagrass studies has not declined so precipitously. There are 14 co-authors of this report.

With kind regards,
Oliver K. Manuel
dachpyarvile
1 / 5 (1) Jul 05, 2009
Seagrass destruction is caused by various pollutants in the runoff of water into the ocean. There is no question in my mind of it. The same pollution is also causing coral bleaching. And, that pollution is not CO2.

We had better knock off focusing on CO2 and ignoring our pollution problem or we will be losing far more than seagrass and coral.