[ASC-media] The mystery of the missing sea nymph - solved!

Clare.Peddie at csiro.au Clare.Peddie at csiro.au
Mon Nov 28 09:54:03 EST 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." 

More information: http://www.clw.csiro.au/acws/ 	
 	
Contacts 	

Dr David Fox 	
 	 Program Leader Sustainable Catchment and Groundwater Management

 	 CSIRO Land and Water 
Private Bag 
PO Wembley WA 6014 	
Phone: 	+61 8 9333 6273 	
Fax: 	+61 8 9333 6430 	
Mobile: 	+61 0417 937 624 	
Email:	 david.fox at csiro.au <mailto:david.fox at csiro.au> 	
 	  	 	
Or contact me:
Clare
Mobile 0400 035 599 
__________________________
Clare Peddie
Communication Officer
CSIRO Land and Water 
Waite Road, Urrbrae, South Australia
Postal address: PMB 2 Glen Osmond, SA 5064 Australia
Ph: +61 8 8303 8452 Fax: +61 8 8303 8550
Web: www.clw.csiro.au 
 


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