Thursday, January 11, 2018

Mud Scientists: Researchers Seek Answers about How Hurricanes Impact Marshes

There’s a debate raging among environmental scientists: Do hurricanes help or hurt wetlands?

As hard as it may be for residents of storm-ravaged communities like New Orleans to believe, hurricanes can provide some benefits for coastal wetlands by delivering rich sedimentation during storm surge inundation. At the same time, such large storm surges also erode the marsh edges and result in the surface excavation of marsh plants.

So what is the net impact of hurricanes on wetlands?

In December, Ioannis Georgiou, chair of earth and environmental sciences at the University of New Orleans and the Olga Braunstein Professor in Sedimentary Geology, teamed with UNO colleagues and collaborators from Boston University and the Virginia Institute of Marine Sciences to investigate sedimentation in coastal marshes stretching from Florida to South Carolina.

Hurricane Irma made landfall in the Florida Keys on Sept. 10 as a Category 4 storm. While the hurricane tracked over the west coast of Florida, its wind patterns and size created strong onshore winds along the southeast coast, producing storm surges of up to seven feet from northern Florida into South Carolina, according to some estimates.

Supported by a Rapid Response Research grant from the National Science Foundation, the team piled into the R/V Mudlump, a 22-foot aluminum boat, and traveled to backbarrier marsh sites, collecting shallow auger cores, accretion cores and surface sediment samples. Collaborating scientists included Mark Kulp from UNO, Duncan FitzGerald and Zoe Hughes from Boston University, Chris Hein from Virginia Institute of Marine Sciences, and Mike Brown and Tara Yocum from UNO’s Pontchartrain Institute for Environmental Sciences.

The team conducted marsh elevation surveys along 2- to 3-km-wide marsh transects in Amelia Island, Fla., Sapelo Island, Ga., Hilton Head Island, SC, and Cape Romain, SC. Georgiou said the team selected these locations because of the varying physical settings and conditions during Irma. They also had baseline data in two of these locations.

“We want to find out where the sediment is coming from--from the nearby bays or the near-shore ocean, for example--and to learn about the process by which sediment is deposited onto the marsh platform,” Georgiou said. “This research will help us better understand how hurricane events contribute to the long-term resiliency of the marsh.”

The samples collected were kept on ice and are being kept in cold storage in preparation for analysis. The team is now preparing a proposal to NSF to support additional fieldwork and analysis.

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Pontchartrain Institute for Environmental Sciences
UNO Department of Earth and Environmental Sciences
Ioannis Georgiou, PhD
Mark Kulp, PhD