Seagrass ecosystems facing losses

The first comprehensive assessment of the state of seagrass meadows around the world shows the damage that human activities have done to the economically and biologically essential areas, the journal Nature reported. The meadows are among the most threatened ecosystems on earth, scientists say, with loss rates comparable to those of mangroves, coral reefs and tropical rain forests.

Data reported in the Proceedings of the National Academy of Sciences suggests that more than a quarter of the world’s seagrass meadows have been lost since records began 130 years ago. Additionally, the rate of that decline has grown from less than 1% per year before 1940 to 7% per year since 1990.

“Our report of mounting seagrass losses reveals a major global environmental crisis in coastal ecosystems, for which seagrasses are sentinels of change,” wrote study author Frederick Short, of the University of New Hampshire, in the Proceedings of the National Academy of Sciences.

Seagrass — flowering plants that evolved from terrestrial ones — support unique wildlife such as green turtles and dugong. They also act as a vital nursery for fish, supporting populations for coral reefs and commercial fisheries. The meadows further help to stabilise sediment and provide coastal protection, as well as trapping carbon and helping in nutrient transportation.

The vast majority of the decline, experts say, is attributable to human activity, such as nutrient and sediment pollution and the introduction of invasive species. Seagrasses also are likely to be affected by climate change.

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