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Seagrass at risk of extinction

Melbourne: A species of seagrass found only in western and southern Australian waters is at the risk of extinction, says an international study.

The seagrass — Posidonia sinuosa — is one of 10 seagrasses worldwide identified in the four-year study that are in danger of being lost forever, according to lead author Prof Gary Kendrick at the University of Western Australia.

Posidonia sinuosa is found in Western Australia from Kalbarri through to Eyre on the south coast and also in Cockburn Sound, which has had declining populations for several decades. The seagrass is also found along the South Australian coast as far as Encounter Bay.

"Posidonia sinuosa is declining at an alarming rate — about 1.2 per cent every year," Prof Kendrick said.

According to researchers, the loss of seagrasses has significant repercussions for both ocean ecosystems and for humans as seagrass meadows provide homes, food and nurseries for countless marine creatures, including commercial fish and crustaceans such as the western rock lobster.

They are a major sink for carbon dioxide and are being developed as valuable ecosystems in the global carbon market.

"Globally, the biggest threat to seagrasses is coastal development. Degraded water quality and the mechanical damage from dredging and port, industrial and urban growth on the coast are other major factors.

"Perhaps surprisingly for many people, climate change isn`t identified as a threat. Seagrasses are, in fact, one of the few groups expected to benefit from climate change," said Prof Kendrick.

The seagrass study involved more than 20 leading researchers who used the Red List criteria of the International Union for the Conservation of Nature to determine the conservation status of 72 seagrass species.

It found that Posidonia sinuosa was in "vulnerable" category, the second highest threat classification after "endangered", according to the IUCN system.

"This latest study is the product of four years of international workshops and input from hundreds of seagrass experts. It will provide policy makers around the world with an official guide for seagrass conservation," Prof Kendrick wrote in the `Biological Conservation` journal.

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