Seagrass study calls for chemical cuts

ABC News 26 Feb 08;

A study into why seagrass is disappearing from the South Australian coastline says nitrogen and phosphate levels need to be cut by up to 75 per cent to protect what is left of the fish habitat.

The six year study has just been finished, and says high levels of both nitrogen and phosphate has caused the seagrass to die.

Professor David Fox, who led research on the problem, says the reduction target will be hard to achieve, but is vital.

"This is a target that now sits with government and industry and also natural resource managers and everyone will have to get together now and work towards figuring out what's the best way of achieving that 75 per cent reduction," he says.

Study helps solve seagrass mystery
Brisbane Times 26 Feb 08;

Reduced water quality has been blamed for the loss of seagrasses along the Adelaide coastline over the past 60 or 70 years.

A CSIRO study, involving 60 researchers, investigated the loss of more than 5,000 hectares of seagrasses along the coast since the mid-1930s.

Study director David Fox said it found that many years of near-continuous discharge of nutrient-rich and turbid wastewater had resulted in significant changes and degradation of Adelaide's coastal marine environment.

"This study has focused on the loss of seagrass - mainly Amphibolis and Posidonia - seabed instability and water quality degradation," Prof Fox said.

"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 seafloor becomes less stable and promotes a further loss of seagrass."

Prof Fox said moves to improve water quality over the past 10 years had improved the marine environment.

But he said large scale recovery of seagrass meadows required continued reductions in coastal discharge and a significant replanting effort.