Wednesday, August 24, 2016

Marshes Beat Droughts with Mussel Power

Co-operation between species can make ecosystems more resilient, so that marshes beat droughts far faster than they could otherwise, US scientists find.

Wild mussels: In the US they help to ensure that saltmarshes can survive severe droughts. (Image Credit: ceridwen via Wikimedia Commons) Click to Enlarge.
Florida scientists have worked out what it takes to help a coastal salt marsh survive drought. It takes an ecosystem of just two species:  the prevailing grasses, and a colony of mussels.

With these two partners clustered together in the drying mud, a coastal wetland can recover from prolonged drought in less than a decade.  Without the mussels, recovery could take more than a century.
Since 40% of the planet lives by the coasts, and since drought in the US southeast seems to be on the increase, with three severe droughts since 1999, the research is of more than academic interest.

Natural defense
Coastal wetlands are important both environmentally and economically:  they represent a natural defense against coastal flooding and tropical windstorm damage as well as a wildlife resource and a nursery for coastal fisheries.

Researchers have warned that, if global warming is not contained, the world’s coastal cities could be losing $1 trillion a year by 2050.  And things could get worse as coastal developments are hit ever harder.

After the devastation of New Orleans and New York by hurricanes in 2005 and 2012, scientists have repeatedly confirmed that natural barriers – healthy marshlands, mangrove forests and coral reefs – offer the best and most cost-effective buffer against rising sea levels and roaring winds.

The Florida scientists report in the journal Nature Communications that at the end of a severe, two-year drought in June 2012, they studied nine stretches of marsh along 150 miles of Atlantic coastline from Georgia to South Carolina.  These had been hit by serious losses of the cordgrass Spartina alterniflora that holds the wetland sediments together.

Root reservoirs
They found that, wherever there were clusters of the bivalve Geukensia demissa, a mussel, in the mud around the stems of the plants, the grass had a 64% chance of surviving.  Without additional mussel-power, the probability of survival fell to 1%.

Read more at Marshes Beat Droughts with Mussel Power

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