CANBERRA, Feb. 15 (Xinhua) -- The number of rare shellfish reefs off the coast of Australia has declined by up to 99 percent since British colonization, a new study revealed on Thursday.
Shellfish reefs are formed by millions of oysters or clams clustering together at the mouth of a river where the tide meets the stream, known as an estuary.
A study released by Nature Conservancy Australia on Thursday revealed that the number of reefs formed by Ostrea angasi, Australian flat oysters, had declined 99 percent from 118 to just one in Tasmania.
The number of rock oyster reefs also fell sharply, down 90 percent from 60 known historical locations to just six surviving reefs.
The decline of shellfish reefs is even more drastic than that of the Great Barrier Reef, which has suffered from mass coral bleaching, and kelp forests which have shrunk by 90 percent off the coast of Western Australia.
Ian McLeod, a co-author of the study and professor at James Cook University, said that the main reasons for the decline of the reefs were over-fishing, destructive fishing practices, decline in water quality and invasive species.
"For many Australians today, the Great Barrier Reef probably first springs to mind as our most endangered ocean ecosystem," McLeod said in a media release on Thursday.
"While it and other coral reefs are indeed under threat, it's the shellfish reefs that have really suffered the most. It's just that most of them disappeared before we were born so people aren't aware we've lost them."
Chris Gillies, marine manager at Nature Conservancy Australia and author of the study, said that the data collected in the study would be used in an application for shellfish reefs to be included as a threatened ecosystem under the Environment Protection and Biodiversity Conservation Act.
Nature Conservancy Australia already has shellfish reef restoration projects either planned or underway in every Australian state.
"At The Nature Conservancy we have shellfish reef restoration projects underway in Port Phillip Bay, Victoria; Gulf St Vincent, South Australia; and Oyster Harbour, Western Australia," Gillies said.
"At an eventual size of 20 hectares, Windara Reef in South Australia will be the largest shellfish reef restoration project ever undertaken in Australia."
