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U.S. Department of the Interior
U.S. Geological Survey
National Wetlands Research Center
700 Cajundome Blvd.
Lafayette, LA 70506

Contact: Gabrielle Boudreaux Bodin
Phone: 337-266-8655
Fax: 337-266-8541
For Release: June 5, 2001



Marshes Green in Early Spring Now Turning Brown

U.S. Geological Survey scientists are seeing a new wave of browning in patches of Louisiana coastal salt marsh that had survived last year's dieback and were green as recently as March and April.

Last year an unprecedented amount of marsh vegetation - more than 100,000 acres of smooth cordgrass (Spartina alterniflora) - disappeared in coastal southeastern Louisiana due to a poorly understood phenomenon, referred to as brown marsh. More than 40 research scientists throughout the state are studying sites along the coast to find the cause. Likely causes range from drought to disease.

While researching the cause, scientists are trying to get a handle on the extent of the browning, which seems to be changing monthly. Many of the previously surviving patches from last year and this spring are now browning and some are completely brown and look dead, according to research scientist Tommy Michot at the USGS National Wetlands Research Center, headquartered in Lafayette.

"The 100,000 plus acres of dieback area we found last year are still there, but new brown patches started showing up this year," Michot said. "We estimate that the acreage of brown standing vegetation increased from 2,800 acres this April to 12,500 acres this May."

"If they follow the same pattern as last year, they will likely turn into deadflats by late summer," Michot said. The "deadflats" he refers to are former salt marshes that have become mostly bare and are turning to mud and open water.

Initially Michot thought about a third of the previously affected sites - 33,000 acres - were recovering, but closer ground inspection indicates that much of the green vegetation is showing signs of stress (leaves are turning brown and rolling up).

Michot conducts monthly airplane surveys of the coastal marshes from Vermilion Bay to Breton Sound. Based on his May survey this year of about 1,300 salt marsh sites, he estimates that nearly 30 percent of the marsh in the Terrebonne-Barataria basins, or 100,000 acres, has been lost. He noted that the current extent of dieback within the remaining 70 percent of marsh may be an indicator of things to come.

Parishes affected include Jefferson, Lafourche, Plaquemines and Terrebonne. Michot and other USGS scientists are planning to expand their study sites next month.

This new development worsens the picture presented earlier that some moderately affected areas were showing signs of recovery and beginning to green up. An April resurvey in the Terrebonne and Barataria basins, for example, by Karen L. McKee, USGS; Irving A. Mendelssohn, Louisiana State University; and Michael D. Materne, Natural Resources Conservation Service, reported that the brown marsh area was not expanding in their 20 study sites.

Sites severely stressed last summer remain in serious condition, agreed Robert Twilley, Director, Center for Ecology and Environmental Technology, University of Louisiana at Lafayette. He said, "There were isolated patches of recovery, but the salt marsh region of Terrebonne and Barataria bays remain highly disturbed. The level of this disturbance should be of concern given the susceptibility of the coast as we enter another hurricane season and with signs that drier conditions may exist throughout the summer."

Scientists are employing many different techniques to understand and measure what is going on - from using aerial and satellite imagery to developing models that predict the occurrence of brown marsh. The Louisiana Governor's Office is coordinating ongoing state, federal, university and contractor research efforts.

Last year the federal government provided emergency funding of $3 million dollars through the National Oceanic and Atmospheric Administration to the Louisiana Department of Natural Resources to begin the work necessary to understand this phenomenon. Other agencies like the USGS National Wetlands Research Center are providing additional funding to study the marsh dieback.

Smooth cordgrass grows in saline marshes along the Gulf of Mexico and the eastern U.S. coast. This highly productive ecosystem provides critical habitat and nutrition for many birds, fish and invertebrates.

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