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Archive for Thursday, August 12, 2010

Marshes show signs of regrowth

August 12, 2010

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Cypress trees and salvinia floating on the water is seen at water level Friday in a cypress swamp, which adjoins marsh that stretches to the Gulf of Mexico in Barataria Preserve, part of Jean Lafitte National Park and Reserve, outside Lafitte, La. This bay that was the scene of the first startling images of oil-caked birds already has shoots of marsh grass and mangroves growing back. The marsh is healing itself.

Cypress trees and salvinia floating on the water is seen at water level Friday in a cypress swamp, which adjoins marsh that stretches to the Gulf of Mexico in Barataria Preserve, part of Jean Lafitte National Park and Reserve, outside Lafitte, La. This bay that was the scene of the first startling images of oil-caked birds already has shoots of marsh grass and mangroves growing back. The marsh is healing itself.

— Shoots of marsh grass and bushes of mangrove trees already are starting to grow back in the bay where just months ago photographers shot startling images of dying pelicans coated in oil from the massive Gulf oil spill.

More than a dozen scientists interviewed by The Associated Press say the marsh here and across the Louisiana coast is healing itself, giving them hope delicate wetlands might weather the worst offshore spill in U.S. history better than they had feared. Some marshland could be lost, but the amount appears to be small compared with what the coast loses every year through human development.

On Tuesday, a cruise through the Barataria Bay marsh revealed thin shoots growing up out of the oiled mass of grass. Elsewhere, there were still gray, dead mangrove shrubs, likely killed by the oil, but even there new green growth was coming up.

“These are areas that were black with oil,” said Matt Boasso, a temporary worker with the Louisiana Department of Wildlife and Fisheries.

‘Sprigs are popping up’

As crude from a blown-out BP well oozed toward the marshes after an April oil-rig explosion, experts had feared it would kill roots in marsh grass, smother the mangroves and ultimately dissolve wetlands that plant life was holding together. State, federal and BP cleanup efforts were focused on preventing that from happening by burning and skimming the oil, blocking it with booms and sand berms and breaking it up with chemical dispersants.

Whether it is a triumph of cleanup work, the marshes’ resiliency or both, scientists have reported regrowth of grasses, black mangrove trees and roseau cane, a lush, tall cane found in the brackish waters around the mouth of the Mississippi River.

“The marsh is coming back, sprigs are popping up,” said Alexander S. Kolker, a marsh expert and coastal geologist in Cocodrie, La., with the Louisiana Universities Marine Consortium.

He’s working with a National Science Foundation team looking at the effect of the BP oil spill on Louisiana’s vast but severely stressed marshland — also known as the Cajun prairie — where trappers, shrimpers and alligator hunters have made their living for generations. Louisiana, the state worst hit by the oil spill, is home to the vast majority of the northern Gulf’s marshland.

Marsh life

Coastal Louisiana is covered in a thick mat of salt marshes that thrive on the edge of the Gulf of Mexico, where land merges with the sea. The marshes provide life support for fauna and flora in the Gulf, said Bob Thomas, a zoologist at Loyola University, and up to 90 percent of commercial fisheries depend on them for some stage of fish development.

Young bull sharks, for example, make a beeline for Louisiana’s estuary to feed on catfish, bait fish and crabs, bulking up before returning offshore to pursue bigger meals, he said.

Many other Gulf species do the same thing. Blue crabs, menhaden and shrimp all come into the marsh to feed on the nutrient rich waters of the bays and marshes, where peaceful grazing is easier. Many freshwater bird species also come down to the marsh to feed, mature and nest.

Marsh loss

Even before the spill, south Louisiana had been losing about 25 square miles of marshland a year, a total of about 2,300 square miles since the 1930s, mostly due to levee construction, logging, shipping and oil drilling. Only about 5,300 square miles of marsh and swamp remain in the state.

Louisiana accounts for about 30 percent of the nation’s coastal marsh and about 90 percent of its marsh loss, according to the U.S. Geological Survey.

Associated Press calculations based on how much coastline government scientists say was affected by the oil spill indicate that at most 3.4 square miles of Louisiana marshland was oiled, an area stretched out over hundreds of miles of coastline. At least some of those areas appear to have begun to bounce back.

Ivor van Heerden, a BP-hired environmental scientist, said the damage may be even less than that. He said federal, state and BP oil spill survey teams have found only 550 acres of marsh that have been oiled, less than 1 square mile.

“In all sectors the plants have continued to grow, even in the very worst areas,” he said.

The National Oceanic and Atmospheric Administration concurred with van Heerden’s figure but said it and other federal agencies are still calculating just how much marsh was oiled and what the effect has been, said agency spokesman Ben Sherman.

Questions remain

Marshland closest to the Gulf took the worst of the spill, absorbing oil and keeping it from oozing farther inland. Even losing a little of it would be a blow to the ecosystem.

Michael Blum, a Louisiana State University biologist who toured the marsh of Barataria Bay on Tuesday, said some of the grass won’t stick around much longer.

“You’re seeing exposed roots,” he said. “The expectation is that you will have loss of the protective sheet, you have marsh that anchors the marsh in place, and if they die off they no longer have that anchor.”

He added: “There’s the possibility that land loss will be accelerated, or there will be a pulse of land loss associated with the BP oil spill. The question is how much and where.”

Many other questions remain about how much environmental damage the spill inflicted. Scientists want to understand the effects of the chemical dispersants BP used to break up the oil and look more closely at how the smallest forms of life, things like fiddler crabs and spiders, have been affected.

“This is sort of the initial macroscopic view,” said Tom Bianchi, an oceanographer and marsh expert at Texas A&M University working with the National Science Foundation team.

He said water from the oiled marsh showed problems. “We did see some particulates, silts and clays coming out of the marsh, clogging our filters,” Bianchi said. That, he added, was a sign of marsh death, which could weaken the soil and lead to erosion.

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