Critical Coastal Habitats: Sustainability, Restoration and Forecasting

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USGS WARC scientists are monitoring both the long- and short-term effects of coastal restoration efforts on ecosystem health in coastal habitats of Louisiana’s Barataria Basin.

The Science Issue and Relevance: TAKING STOCK OF COASTAL RESTORATION

The Mississippi River Deltaic Plain (MRDP) contains 40% of the contiguous U.S. wetlands and provides critical habitat for waterfowl and fisheries, as well as many other benefits, such as storm surge protection for coastal communities. In terms of ecosystem services, biologic productivity, and infrastructural investments, the value of the MDRP’s coastal wetlands exceeds $100 billion. However, the loss rates of MRDP wetlands are among the highest in the world, with nearly 1.2 million acres lost since the 1930s, an area three-fourths the size of Delaware. In response, extensive wetland restoration efforts are ongoing in the MRDP, which have the potential to impact multiple stakeholders, including commercial fisheries, which are valued at $426 million per year.

USGS WARC scientists operate two eddy covariance (EC) sites in coastal habitats of Louisiana’s Barataria Basin (Map 1, US-LA2 and US-LA3). EC is a method that uses high frequency measurements of wind speed and direction, and gas concentrations to estimate exchange between land surfaces and the atmosphere (Picture 1). USGS is monitoring both the long- and short-term effects of coastal restoration efforts on ecosystem health at these sites. US-LA2 is located in a freshwater marsh near the Davis Pond Freshwater Diversion, which began operation in 2002 to combat marsh loss and salinity intrusion. US-LA3 is located in a saltwater marsh in the receiving area for the Mid-Barataria Sediment Diversion project, which is slated to begin in 2022 in an effort to reverse loss of critical coastal habitat. The pretreatment data currently being collected will provide a critical reference point when comparing conditions after the diversion becomes operational.

Map of eddy covariance sites in LA

Map 1. Two eddy covariance (EC) sites in Louisiana’s Barataria Basin operated by USGS WARC scientists. (Public domain.)

Methodology for Addressing the Issue:

TOOLS FOR MONITORING AND FORECASTING

Eddy covariance instrumentation

Picture 1. USGS WARC scientists operate two eddy covariance (EC) sites in coastal habitats of Louisiana’s Barataria Basin. EC is a method that uses high frequency measurements of wind speed and direction, and gas concentrations to estimate exchange between land surfaces and the atmosphere. (Public domain.)

EC can be used as a real time monitor of ecosystem growth and health, producing estimates of whole ecosystem photosynthesis, respiration, evaporation, and transpiration every half hour. EC sites integrate information from an entire ecosystem at high temporal resolution, making them an ideal data source for many applications, including:

•           Monitoring ecosystem resilience to stressors such as sea level rise, changing salinity, storm surges, frost, heat waves, and droughts.

•           Forecasting models of ecosystem productivity and habitat sustainability in a changing world.

•           Linking marsh biogeochemistry to tidal exchanges in aquatic ecosystems (Picture 2).

 

Future Steps:

Data from these EC sites have already contributed to regional and national efforts in modeling primary productivity and methane emissions of wetlands in the U.S.1,2,3. These sites provide the only source of high-frequency, continuous data on wetland ecosystem carbon and water fluxes in coastal Louisiana. We expect that they will serve a critical role in calibrating the type of process-based models necessary for forecasting the sustainability, resilience, and restoration of these critical coastal habitats. Integration with the regional Ameriflux network and the international FLUXNET network of EC sites ensures the availability and visibility of these data to the global research community for many decades to come.

Tidal exchange station

Picture 2. USGS WARC scientists operate tidal exchange stations in coastal habitats of Louisiana’s Barataria Basin.

(Public domain.)