Coastal Louisiana marsh as viewed driving down to LUMCON (the Louisiana University Marine Consortium).
What is the Brown Marsh phenomenon?
Sudden marsh dieback events are not uncommon and have occurred in coastal marshes from the Gulf of Mexico to Maine. Brown Marsh is a term given to the unusually rapid and extensive browning of Louisiana’s saltwater marsh grass Spartina alterniflora, commonly known as oyster grass or smooth cordgrass. One of the most severe events occurred in 2000, when over 100,000 hectares (ha) of salt marsh were impacted in Louisiana’s Mississippi River Delta Plain.
The cause of sudden marsh dieback is still under debate but may be cyclical depending on interactive climate conditions, sea level anomalies, and other biotic factors.
Healthy marshes and barrier islands are important storm buffers. As marshes and barrier islands deteriorate, people and their communities are placed at increased risk from storm events. Further, the continued loss of coastal landmasses could increase the intrusion of saltwater into freshwater drinking sources.
Learn more: USGS Wetland and Aquatic Research Center
Related
What are wetlands? What are wetlands?
Wetlands are transitional areas, sandwiched between permanently flooded deepwater environments and well-drained uplands, where the water table is usually at or near the surface or the land is covered by shallow water. They include mangroves, marshes (salt, brackish, intermediate, and fresh), swamps, forested wetlands, bogs, wet prairies, prairie potholes, and vernal pools. In general terms...
Why are wetlands important? Why are wetlands important?
Wetlands provide habitat for thousands of species of aquatic and terrestrial plants and animals. Wetlands are valuable for flood protection, water quality improvement, shoreline erosion control, natural products, recreation, and aesthetics. Wetlands are among the most productive habitats on earth providing shelter and nursery areas for commercially and recreationally important animals like fish...
Why is elevation data so important to forecasting hurricane impact? Why is elevation data so important to forecasting hurricane impact?
The fundamental lesson of Hurricane Sandy in 2012 (and prior catastrophic storms and hurricanes) was that storm vulnerability is first and foremost a consequence of elevation. The height at which infrastructure, resources, and communities sit in relation to average tides and water levels, storm waves, surge, and flood waters determines their exposure to overwhelmingly powerful damaging forces...
How would sea level change if all glaciers melted? How would sea level change if all glaciers melted?
There is still some uncertainty about the full volume of glaciers and ice caps on Earth, but if all of them were to melt, global sea level would rise approximately 70 meters (approximately 230 feet), flooding every coastal city on the planet. Learn more: USGS Water Science School: Glaciers and Icecaps National Snow and Ice Data Center: Facts about Glaciers U.S. Global Change Research Program: Sea...
Coastal Marsh in Louisiana
Coastal Louisiana marsh as viewed driving down to LUMCON (the Louisiana University Marine Consortium).
Measuring tidal inundation in a marsh shoreline
Joseph Terrano of the USGS St. Petersburg Coastal and Marine Science Center prepares water level loggers to install near the marsh shoreline in Grand Bay National Estuarine Research Reserve, Mississippi.
Joseph Terrano of the USGS St. Petersburg Coastal and Marine Science Center prepares water level loggers to install near the marsh shoreline in Grand Bay National Estuarine Research Reserve, Mississippi.
Sea-Level Rise, El Niño, and Storm Effects on Coastal Tidal Marshes
Sea-Level Rise, El Niño, and Storm Effects on Coastal Tidal MarshesTidal marshes exist as a transitional environment between the land and sea, and provides habitat to fish and wildlife, protects human developments from coastal flooding, and stores carbon at high density, among other important ecosystem services.
Sea-Level Rise, El Niño, and Storm Effects on Coastal Tidal Marshes
Sea-Level Rise, El Niño, and Storm Effects on Coastal Tidal MarshesTidal marshes exist as a transitional environment between the land and sea, and provides habitat to fish and wildlife, protects human developments from coastal flooding, and stores carbon at high density, among other important ecosystem services.
High stakes, big questions in marsh grass die-back
High stakes, big questions in marsh grass die-backBrown patches and brown stems show stress in this phagmites (roseau cane) stand in Pass A Loutre Wildlife Management Area, a tract of state-owned land in Louisiana's bird foot delta, where the Mississippi River meets the Gulf of Mexico. An ongoing phragmites was first discovered in spring 2017 and blamed on an invasive scale insect from Asia.
High stakes, big questions in marsh grass die-back
High stakes, big questions in marsh grass die-backBrown patches and brown stems show stress in this phagmites (roseau cane) stand in Pass A Loutre Wildlife Management Area, a tract of state-owned land in Louisiana's bird foot delta, where the Mississippi River meets the Gulf of Mexico. An ongoing phragmites was first discovered in spring 2017 and blamed on an invasive scale insect from Asia.
Brown Marsh in Southeast Louisiana
Brown Marsh observed in southeastern Terrebonne Basin, La
Brown Marsh observed in southeastern Terrebonne Basin, La
Brown Marsh in Southeast Louisiana
Brown Marsh observed in southeastern Terrebonne Basin, La
Brown Marsh observed in southeastern Terrebonne Basin, La
Brown Marsh in Southeast Louisiana
Brown Marsh observed in southeastern Terrebonne Basin, La.
Brown Marsh observed in southeastern Terrebonne Basin, La.
Using Airboats For Marsh Studies
National Wetlands Research Center scientists use air boats for the marsh studies along the Gulf of Mexico.
National Wetlands Research Center scientists use air boats for the marsh studies along the Gulf of Mexico.
Surface sediment sampling in a vegetated Louisiana saltmarsh.
Surface sediment sampling in a vegetated Louisiana saltmarsh.USGS researchers Jennifer Agee and Le Kieu sampling surface sediment in a vegetated Louisiana saltmarsh. Photographer: M. Marvin-DiPasquale.
Surface sediment sampling in a vegetated Louisiana saltmarsh.
Surface sediment sampling in a vegetated Louisiana saltmarsh.USGS researchers Jennifer Agee and Le Kieu sampling surface sediment in a vegetated Louisiana saltmarsh. Photographer: M. Marvin-DiPasquale.
Related
What are wetlands? What are wetlands?
Wetlands are transitional areas, sandwiched between permanently flooded deepwater environments and well-drained uplands, where the water table is usually at or near the surface or the land is covered by shallow water. They include mangroves, marshes (salt, brackish, intermediate, and fresh), swamps, forested wetlands, bogs, wet prairies, prairie potholes, and vernal pools. In general terms...
Why are wetlands important? Why are wetlands important?
Wetlands provide habitat for thousands of species of aquatic and terrestrial plants and animals. Wetlands are valuable for flood protection, water quality improvement, shoreline erosion control, natural products, recreation, and aesthetics. Wetlands are among the most productive habitats on earth providing shelter and nursery areas for commercially and recreationally important animals like fish...
Why is elevation data so important to forecasting hurricane impact? Why is elevation data so important to forecasting hurricane impact?
The fundamental lesson of Hurricane Sandy in 2012 (and prior catastrophic storms and hurricanes) was that storm vulnerability is first and foremost a consequence of elevation. The height at which infrastructure, resources, and communities sit in relation to average tides and water levels, storm waves, surge, and flood waters determines their exposure to overwhelmingly powerful damaging forces...
How would sea level change if all glaciers melted? How would sea level change if all glaciers melted?
There is still some uncertainty about the full volume of glaciers and ice caps on Earth, but if all of them were to melt, global sea level would rise approximately 70 meters (approximately 230 feet), flooding every coastal city on the planet. Learn more: USGS Water Science School: Glaciers and Icecaps National Snow and Ice Data Center: Facts about Glaciers U.S. Global Change Research Program: Sea...
Coastal Marsh in Louisiana
Coastal Louisiana marsh as viewed driving down to LUMCON (the Louisiana University Marine Consortium).
Coastal Louisiana marsh as viewed driving down to LUMCON (the Louisiana University Marine Consortium).
Measuring tidal inundation in a marsh shoreline
Joseph Terrano of the USGS St. Petersburg Coastal and Marine Science Center prepares water level loggers to install near the marsh shoreline in Grand Bay National Estuarine Research Reserve, Mississippi.
Joseph Terrano of the USGS St. Petersburg Coastal and Marine Science Center prepares water level loggers to install near the marsh shoreline in Grand Bay National Estuarine Research Reserve, Mississippi.
Sea-Level Rise, El Niño, and Storm Effects on Coastal Tidal Marshes
Sea-Level Rise, El Niño, and Storm Effects on Coastal Tidal MarshesTidal marshes exist as a transitional environment between the land and sea, and provides habitat to fish and wildlife, protects human developments from coastal flooding, and stores carbon at high density, among other important ecosystem services.
Sea-Level Rise, El Niño, and Storm Effects on Coastal Tidal Marshes
Sea-Level Rise, El Niño, and Storm Effects on Coastal Tidal MarshesTidal marshes exist as a transitional environment between the land and sea, and provides habitat to fish and wildlife, protects human developments from coastal flooding, and stores carbon at high density, among other important ecosystem services.
High stakes, big questions in marsh grass die-back
High stakes, big questions in marsh grass die-backBrown patches and brown stems show stress in this phagmites (roseau cane) stand in Pass A Loutre Wildlife Management Area, a tract of state-owned land in Louisiana's bird foot delta, where the Mississippi River meets the Gulf of Mexico. An ongoing phragmites was first discovered in spring 2017 and blamed on an invasive scale insect from Asia.
High stakes, big questions in marsh grass die-back
High stakes, big questions in marsh grass die-backBrown patches and brown stems show stress in this phagmites (roseau cane) stand in Pass A Loutre Wildlife Management Area, a tract of state-owned land in Louisiana's bird foot delta, where the Mississippi River meets the Gulf of Mexico. An ongoing phragmites was first discovered in spring 2017 and blamed on an invasive scale insect from Asia.
Brown Marsh in Southeast Louisiana
Brown Marsh observed in southeastern Terrebonne Basin, La
Brown Marsh observed in southeastern Terrebonne Basin, La
Brown Marsh in Southeast Louisiana
Brown Marsh observed in southeastern Terrebonne Basin, La
Brown Marsh observed in southeastern Terrebonne Basin, La
Brown Marsh in Southeast Louisiana
Brown Marsh observed in southeastern Terrebonne Basin, La.
Brown Marsh observed in southeastern Terrebonne Basin, La.
Using Airboats For Marsh Studies
National Wetlands Research Center scientists use air boats for the marsh studies along the Gulf of Mexico.
National Wetlands Research Center scientists use air boats for the marsh studies along the Gulf of Mexico.
Surface sediment sampling in a vegetated Louisiana saltmarsh.
Surface sediment sampling in a vegetated Louisiana saltmarsh.USGS researchers Jennifer Agee and Le Kieu sampling surface sediment in a vegetated Louisiana saltmarsh. Photographer: M. Marvin-DiPasquale.
Surface sediment sampling in a vegetated Louisiana saltmarsh.
Surface sediment sampling in a vegetated Louisiana saltmarsh.USGS researchers Jennifer Agee and Le Kieu sampling surface sediment in a vegetated Louisiana saltmarsh. Photographer: M. Marvin-DiPasquale.
Updated Date: November 28, 2025