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Dr. Kathryn Smith and Joseph Terrano visited Grand Bay National Estuarine Research Reserve (GBNERR) last week to deploy oceanographic sensors in the estuary, swap out net sedimentation tiles (NSTs) and collect sediment samples. This research will help assess the effects of nearby constructed subtidal reefs on the marsh shoreline.

Two white rectangular platforms mounted with metal cylindrical objects sit on the deck of a boat chained to cinderblocks
Oceanographic sensors ready to be deployed to the bottom of the estuary at Grand Bay National Estuarine Research Reserve (GBNERR) as part of the Estuarine and Marsh Geology (EMrG) project. The instruments will remain on the seafloor for six weeks to measure total suspended solids (sediment), water level, dissolved oxygen, and waves near a constructed subtidal reef. The sensor deployment is part of a study to examine the impacts of these reefs on nearby marsh shorelines, which have been eroding at approximately 2 meters per year and causing marsh loss. Natural and nature-based features, such as these subtidal reefs, are possible solutions to coastal erosion, but more research is necessary to understand their long-term impacts.

The team, including Dr. Kathryn Smith (USGS St. Petersburg Coastal and Marine Science Center; SPCMSC), Joseph Terrano (SPCMSC), Alisha Ellis (USGS), Matthew Virden (Mississippi State University [MSU]), Michael Archer (Grand Bay National Estuarine Research Reserve [GBNERR]), Michael Brochard (GBNERR), and Jonathan Pitchford (GBNERR), conducted field work last week in Grand Bay. The team deployed several oceanographic sensors on the seafloor of the estuary to collect time-series data on total suspended solids (sediment), water level, dissolved oxygen, and waves near a constructed subtidal reef. The sensor deployment is a joint USGS/GBNERR/MSU study to collect time series oceanographic and sediment data to examine the impacts of these reefs on nearby marsh shorelines, which have been eroding at approximately 2 meters per year and causing substantial marsh loss. The field work is part of a year-long study to monitor both marsh and nearshore sediment flux to examine short-term impacts of the constructed reefs, but will also provide essential data for developing coupled marsh-hydrodynamic models that can be used to examine long-term impacts. Natural and nature-based features, such as these subtidal reefs, are possible solutions to coastal erosion, but more research is necessary to understand their short- and long-term impacts on sediment transport, marsh accretion, and shoreline erosion.

This sensor monitoring was funded by the USGS Coastal and Marine Hazards and Resources Program and the NOAA Effects of Sea Level Rise (ESLR) Program. Grand Bay marshes are an important natural resource for coastal Mississippi, providing recreational opportunities, habitat for fish and other wildlife, as well as protecting upland coastal communities from storm surge.

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