Seagrass at risk of extinction
"Globally, the biggest threat to seagrasses is coastal development."
Image: ermingut/iStockphoto

A species of seagrass found only in western and southern Australian waters is at risk of extinction, according to a four-year international study.

The seagrass - Posidonia sinuosa - is one of 10 seagrasses worldwide identified in the study that are in danger of being lost forever, according to one of the study's authors, Winthrop Professor Gary Kendrick of the Oceans Institute 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," Professor Kendrick said.  The loss of seagrasses has significant repercussions for both ocean ecosystems and for humans.

Seagrass meadows provide homes, food and nurseries for countless marine creatures, including commercial fish and crustaceans such as the western rock lobster.

They are also 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," Professor Kendrick said.

"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."

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

It found that Posidonia sinuosa was in the ‘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," Professor Kendrick said.  "It will provide policy makers around the world with an official guide for seagrass conservation."

The study was published in the journal Biological Conservation and is available online.

Editor's Note: Original news release can be found here.