Jun 30, 2009

Destruction of seagrass on a par with loss of rainforests and coral reefs

While the world has focused on the destruction mankind has brought to coral reefs, the massive loss of an equally important ecosystem has been widely ignored.

Now the first comprehensive assessment of the state of seagrass meadows around the world has revealed the damage that human activities have wrought on these economically and biologically essential areas.
Seagrass meadows on Cyrene Reef facing our container terminal.

A synthesis of quantitative data from 215 sites suggests that the world has lost more than a quarter of its meadows in the past 130 years, since records began, and that the rate of that decline has grown from less than 1% per year before 1940 to 7% per year since 1990.

"Seagrass loss rates are comparable to those reported for mangroves, coral reefs and tropical rainforests, and place seagrass meadows among the most threatened ecosystems on earth," write the authors of the synthesis, which is published this week in the Proceedings of the National Academy of Sciences1. "Our report of mounting seagrass losses reveals a major global environmental crisis in coastal ecosystems, for which seagrasses are sentinels of change."

As well as supporting unique wildlife such as green turtles (Chelonia mydas) and dugong (Dugong dugon), seagrass meadows also serve as a vital nursery for fish, supporting populations for coral reefs and commercial fisheries. They also serve to stabilize sediment and provide coastal protection, as well as trapping carbon and helping in nutrient transportation.

Some fishes in the seagrass meadows of Cyrene Reef, being tagged by Collin.

Study author Frederick Short, a researcher at the University of New Hampshire, Durham, admits that there is "not that much data" available on seagrass, so the total loss is difficult to pin down exactly.

[Thus efforts such as TeamSeagrass will contribute towards closing the data gaps.}

The vast majority of this decline, say Short and other experts, is attributable to human activity. Nutrient and sediment pollution from nearby human activities and the introduction of invasive species are both contributing to their decline.

Giuseppe DiCarlo, marine climate change manager at Conservation International and a member of the steering committee of the World Seagrass Association, told Nature News that even where seagrass meadows have been lost there is the opportunity for recovery if protection via the designation of Marine Protected Areas can be brought in.

Full media articles on this study on the wildsingapore news blog.

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