Research explores how coastal changes affect wildlife

(12/14/20) BATON ROUGE, La. — The LSU AgCenter has announced publication of research aimed at helping coastal planners predict the results of flood protection and wetland restoration on coastal wildlife.

The research was published in the “Wetlands” journal by U.S. Geological Service ecologist Brett Patton, LSU AgCenter coastal ecologist Andy Nyman and Megan La Peyre, assistant unit leader at the USGS.

The article, “Living on the Edge: Multi-Scale Analyses of Bird Habitat Use in Coastal Marshes of Barataria Basin, Louisiana, USA,” is online at https://bit.ly/3qVw75H.

Patton conducted the research as part of her master’s thesis, which was directed by Nyman.

Nyman noted that wetland loss, navigation channels, flood protection and wetland restoration can replace open water with marsh grasses, or vice versa, and replace fresh marshes with saline marshes, or vice versa.

“The research produced standardized measurements of waterbirds using marsh grasses, waterbirds using marsh ponds and waterbirds using the edge habitat where grass meets ponds,” he said.

Alone, the measurements are of interest to wildlife managers and other naturalists, he said. But when combined with powerful computer models simulating water salinity, water depth, sedimentation, subsidence and wetland change, the standardized bird counts can allow coastal planners to objectively compare the likely response of waterbird abundance to different projects being considered.

Coastal Louisiana wetlands are one of the most critically threatened environments in the United States, according to the U.S. Geological Service.

These wetlands are in peril because Louisiana currently experiences greater coastal wetland loss than all other states in the contiguous United States combined.

Nyman often collaborates on coastal research with La Peyre, who is housed in the AgCenter School of Renewable Natural Resources, where she also is on the faculty.

“The general response of many fish and wildlife to coastal change is recognized by fishermen, hunters and coastal planners, but the size of the changes to fish and wildlife are debatable,” Nyman said.

He explained that edge habitat is particularly valuable to fish and wildlife.

“From prairie potholes to coastal marshes, edge habitats are widely recognized as not only attracting fish and wildlife but actually increasing fish and wildlife numbers,” he said. “This was first demonstrated during the mid-1900s for prairie potholes in the Midwest.”

A previous graduate student, Jessica O’Connell, first demonstrated this for coastal marsh ponds and waterbirds in her 2010 research.

“The new research is unique because it produced standardized counts of waterbirds using marsh grasses, marsh ponds and the edge habitat where grass meets ponds, and it did so in fresh marsh and salt marsh,” Nyman said.

Patton conducted 120 successful surveys and identified 1,117 birds of 68 species during 2014 and 2015.

Of the six habitats compared, fresh edges clearly supported the most birds, and waterbirds were second most abundant in fresh marshes, which supported about 50% of the number in fresh edges. Salt edges supported about 40% of the number in fresh edges.

“Fresh ponds and salt ponds supported similar amounts, 30% and 25% as many birds as fresh edges,” Nyman said. “Salt marsh supported the fewest waterbirds, about 15% in fresh edges.”

Those patterns remained even after eliminating the most abundant bird, the red-winged blackbird.

As in the research published in 2010, duck estimates were least reliable because ducks are so much warier of people, he said.

Nyman, who led teams that created fish and wildlife models for Louisiana’s 2007 and 2012 Master Plans for a Sustainable Coast, suspects that it is too late to use the new data in Louisiana’s 2023 update to its Master Plan.

“I just hope the new data are used to create new models that coastal residents and managers can consider as flood protection and wetland restoration proceed,” he said.

Salt Marsh.

Saltwater marsh near Port Fourchon, Louisiana. Photo by Andy Nyman/LSU AgCenter

Fresh marsh.

Freshwater marsh at the mouth of the Mississippi River downstream of Venice, Louisiana. Photo by Andy Nyman/LSU AgCenter

12/14/2020 5:43:51 PM
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