March of the Mangroves to the Climate Change Beat


Mangroves. Photo by Kyle Cavanagh, Brown U.
Mangroves. Photo by Kyle Cavanagh, Brown U.

As sailors navigate the Intracoastal Waterway southward along the Atlantic seaboard, they pass many miles of salt marshes. On sunny days the marshes shine golden in the sun, from New Jersey to the north and many miles to the south along the twists and turns of the shallow passage ways.

The marshes, if they hadn’t been take out by developers, ¬†used to continue all the way to the Florida coast. But the grasses are now rapidly giving way to tropical mangroves just south of Cocoa Beach in a development that is worrying scientists, according to a recent report.

Climate change has reduced the severity of hard freezes, which is allowing the marshes to be replaced by the mangroves we associate with tropical and subtropical zones. Essentially they provide the same benefits; roosts and rookeries for wading birds, a nursery for young fish, a buffet for crustaceans, molluscs, and fish. They filter salt water into a more brackish water and generally clarify it.

The first species to show up is the Black Mangrove. It can re grow after a hard freeze. Mangroves in general provide somewhat better protection from our increasingly severe weather events. They are a buffer against hurricanes, strong wave action, and run off. They trap debris and silt to prevent soil loss.

It would seem that a barrier of these tropical trees would protect the Jersey shoreline and mitigate the damage from huge storms. But it is more probable developers would tear them up in their lust for profitable waterfront property.

A good example: development in Tampa Bay and Biscayne Bay near Miami caused many acres of mangroves to disappear –a loss never to be rectified. In the south, mangroves provide homes for snakes, crocodiles and even food for dwarf deer. Each acre breaks down an amazing seven and a half tons of leaf litter each year which feeds all kinds of sea life. They are interdependent with the coral reef system.

The switch from salt marsh to mangroves is happening faster than expected. Three thousand more acres appeared in three decades between St. Augustine and Cape Canaveral. Scientists are tracing the change on the ground and from outer space.

“Along a 50-mile stretch of the central Florida coast south of St. Augustine, the amount of mangrove forest doubled between 1984 and 2011, the scientists found after analyzing satellite images,” according to report in the New York Times.

There are not necessarily any negative effects from this march northward of the mangroves but rapid change in the our habitat shows the power of climate change yet again.

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