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Solving the seagrass crisis



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ARC CoE for Environmental Decisions (CEED)

M e d i a R e l e a s e

Solving the seagrass crisis

September 24, 2013 - for immediate release

The world’s seagrass meadows are in diabolical trouble - but Australian scientists

say we can still save them if we act early, even as sea levels rise.

“We’re currently losing around 7 per cent of the global seagrass area every year

due to a combination of human impacts - and those losses are likely to accelerate

as sea levels rise,” says Dr Megan Saunders a University of Queensland Global

Change Institute researcher collaborating with the ARC Centre of Excellence for

Environmental Decisions (CEED)

A big threat to seagrass is loss of sunlight, she says. As waters deepen due to

sea level rise and become murkier due to human activities on land, seagrass

meadows in deeper waters are deprived of the light they need to stay alive.

In new research reported in the journal Global Change Biology, Dr Saunders and

colleagues used Moreton Bay in Australia, a Ramsar wetland area, as a

laboratory to investigate the fate of seagrass meadows generally as sea levels

rise by an expected 1.1 metres during this century.

“Compared to coral reefs, seagrasses are the ugly duckling of marine

ecosystems. They get nowhere near the publicity they deserve - yet they are vital

both to the oceans and to humanity,” Dr Saunders says.

“They are major nurseries for fish and prawns, and so support our food supply.

They trap huge amounts of carbon - and could sequester even more if we look

after them. They cleanse the oceans by trapping sediment and nutrients.”

The team’s research indicates that a 1.1 metre rise in sea level would result in a

17 per cent decline in seagrass cover in Moreton Bay due to the loss of light

alone. Equivalent losses could occur globally, although exact numbers would

depend on the location, she adds.

Seagrasses are a vital factor in the battle against climate change, Dr Saunders

says. They trap an estimated 48-112 million tonnes of carbon every year. Their

loss means this carbon will be re-released into the atmosphere, accelerating

global warming.

“Equally, if we can stabilise or even expand the area of seagrass beds globally,

they can lock up an awful lot of carbon and help slow climate change - as well as

restoring degraded fisheries.”

Dr Saunders says the keys to saving and regenerating the world’s seagrass beds

are:

• Controlling erosion and runoff in river catchments on land by revegetating bare

areas of farmland, river banks etc and better managing nutrient and soil runoff

from cities

• Local authorities adopting much more flexible coastal planning for development

which allows for future seagrass meadows to expand as sea levels rise.

“This probably means preventing new developments and the construction of sea

walls and levees in the coastal zone. And potentially removing things like houses

and roads from newly flooded areas, as sea levels rise, so that salt marshes,

mangroves and seagrasses can colonise the area.”

The Moreton Bay research indicates that such a “coastal retreat” strategy could

reduce the decline in seagrass cover from 17 to 5 per cent.

The success of the plan depends on creating light conditions at the ‘deep edge’ of

seagrass meadows which allow seagrass species to continue to flourish.

“This is the sort of information our coastal planners will need as we seek to cope

with the changes imposed by sea level rise and other impacts of climate change,”

she explains. “It also means we can think further ahead about what is needed to

keep these essential ecosystems alive and thriving by allowing them to move to

occupy new niches as they emerge.”

Her article appears in Issue 72 of Decision Point at: http://www.decision-

point.com.au/

The paper Coastal retreat and improved water quality mitigate losses of seagrass

from sea level rise by Saunders MI, Leon J, Phinn SR, Callaghan DP, O’Brien KR,

Roelfsema, CM, Lovelock CE, Lyons MB, Mumby PJ (2013) appears in Global

Change Biology at http://onlinelibrary.wiley.com/doi/10.1111/gcb.12218/full

The research was a collaboration between the ARC funded Australia Sea Level

Rise Partnership (ASLRP), based at the Global Change Institute at the University

of Queensland, and CEED.

CEED is the Australian Research Council Centre of Excellence for Environmental

Decisions. CEED’s research tackles key gaps in environmental decision making,

monitoring and adaptive management.

More information:

Dr Megan Saunders, CEED, ASLRP and UQ, +61 (0)7 3443 3116 or +61 (0)432

034 814

Prof Cath Lovelock, UQ, +61(0) 429854507

Prof Stuart Phin, UQ, +61 (0) 401 012 996

Karen Gillow, communication manager CEED, +61 (0) 402 674 409

Carolyn Varley, UQ media, +61 (0)7 3365 1120 c.varley@uq.edu.au

www.ceed.edu.au

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