The mystery of the missing sea nymph – solved!

Nov 28, 2005
The mystery of the missing sea nymph – solved!

A four-year study into the mysterious and rapid decline of Adelaide's coastal seagrass species – mainly Amphibolis (commonly known as 'sea nymph' or 'wire weed') and Posidonia – is close to completion.

The $4m Adelaide Coastal Waters Study, initiated by the State Government, was designed to address concerns about the decline in coastal water quality and the loss of more than 5000 hectares of shallow sub-tidal seagrass along the metropolitan coast since the mid-1930s.

The six research teams, involving some 60 scientists and technical staff from a number of research organisations, will meet today (Monday) to review their results – with the final report due to be delivered to the South Australian Government in July, 2006.

Study Director, Professor David Fox from CSIRO Land and Water says: “We have developed a big-picture view of Adelaide's coastal marine environment and can now start looking at how to prevent further degradation and hopefully even bring seagrass back.

“Seagrass meadows are primary producers at the bottom of the food chain and they provide natural habitat for many species of fish, crustaceans, and other marine animals.

“Taking the seagrasses out of the system causes a 'domino effect', where the sea floor becomes less stable and hence promotes a further loss of seagrass.”

The scientists have pieced together the complex story of seagrass loss, which begins with poor water quality (particularly elevated nutrients and suspended matter). Amphibolis plays a critical role in stabilising seagrass beds but has been lost from inshore waters, particularly during the mid-1970s.

“This was a period when urban development was occurring at its greatest rate, waste-water treatment plants were discharging higher loads of nutrients, and sewage sludge was being discharged offshore,” Professor Fox says.

As Amphibolis was lost, it is believed that natural erosion impacted on the other dominant species Poisidonia . According to Professor Fox the initial loss was from close to shore and this has progressed seaward – a reversal of the usual situation where the loss starts in deeper waters and moves landward.

The study also found that the government's water quality improvement plans of the past 10 years, coupled with reduced volumes discharged to the sea, have made a big difference. Most nutrient levels have been substantially reduced and the amount of some metals in the effluent discharged by wastewater treatment plants is only 10 per cent of what it was.

“However we must not be complacent,” Professor Fox says. “Our research has shown that although water quality is generally very much better than it was a decade ago, seagrass meadows have not, for the most part, recovered.

“The challenge now is how to preserve the relatively un-impacted coastal environment further south of Adelaide, in the face of increased pressure from urban sprawl, while trying to reverse the degradation that has already occurred.”

Source: CSIRO

Explore further: Research geared to keep women from fleeing IT profession

add to favorites email to friend print save as pdf

Related Stories

High-CO2 world threatens seabed life

Jun 20, 2014

Environmental change is transforming many parts of the north-east Atlantic seabed, and according to a newly-published paper this will almost certainly get worse in the coming decades.

Loss of coastal seagrass habitat accelerating globally

Jun 29, 2009

An international team of scientists warns that accelerating losses of seagrasses across the globe threaten the immediate health and long-term sustainability of coastal ecosystems. The team has compiled and analyzed the first ...

Recommended for you

Bronze Age wine cellar found

15 hours ago

A Bronze Age palace excavation reveals an ancient wine cellar, according to a study published August 27, 2014 in the open-access journal PLOS ONE by Andrew Koh from Brandeis University and colleagues.

Orphaned children can do just as well in institutions

15 hours ago

The removal of institutions or group homes will not lead to better child well-being and could even worsen outcomes for some orphaned and separated children, according to new findings from a three-year study across five low- ...

User comments : 0