Grand Bay National Estuarine Research Reserve, Mississippi

June 26, 2012, 9:13 am
Source: NOAA
Content Cover Image

Sunset over Bayou Cumbest, Grand Bay NERR. Photo credit: Gretchen Waggy.

The Grand Bay National Estuarine Research Reserve is one of the most biologically productive estuarine ecosystems in the Gulf of Mexico region, supporting several rare or endangered plant and animal species, numerous important marine fishery resources, diverse habitat types and archaeological sites.

Location: The reserve is located in Jackson County in southeast Mississippi between Pascagoula and the Alabama state line.

Total Acreage: 18,400

Designation: 1999

Lead State Agency: Mississippi Department of Marine Resources.

Map of the core and buffer areas of the Grand Bay NERR, 2007.


The reserve encompasses coastal bay, expansive saltwater marshes, maritime pine forest, pine savanna and pitcher plant bogs. It supports extensive and productive oyster reefs and seagrass habitats. It also serves as nursery area for many of the Gulf of Mexico's important recreational and commercial marine species, such as shrimp, blue crab, speckled trout, red fish.

As part of the Grand Bay Savannah Conservation Partnership, the Grand Bay Reserve is participating in a prescribed burn management program for the East Mississippi Sound Region. This project is widely supported by local and state government agencies as well as the oil and gas industry with facilities in adjacent fire-dependent woodlands.

The bay is within the National Estuarine Research Reserve System (NERRS), a network of estuarine habitats protected and managed for the purposes of long-term research, education, and coastal stewardship. Established by Congress in 1972 as part of the Coastal Zone Management Act (CZMA), the NERRS is administered as a partnership between the National Oceanic and Atmospheric Administration (NOAA) and the coastal states.

An estuary is located where the rivers meet the sea-where salt- and fresh water mix to form brackish water. Technically, "an estuary is a partially enclosed body of water where saltwater from the sea mixes with the fresh water from rivers, streams and creeks. These areas of transition between the land and the sea are tidally driven, like the sea, but sheltered from the full force of ocean wind and waves, more like a river. Estuaries are generally enclosed in part by the coastline, marshes and wetlands: the seaward border may be barrier islands, reefs and sand- or mud flats." Estuaries occur along the edges of the Earth's one big ocean.

The Grand Bay National Estuarine Research Reserve (GNDNERR) is a marine protected area located in extreme southeastern Mississippi in Jackson County near the small community of Pecan. The GNDNERR is comprised of approximately 18,000 acres, found chiefly within the Grand Bay National Wildlife Refuge and the Grand Bay Savanna Coastal Preserve. This reserve contains a variety of wetland habitats, both tidal and non-tidal, such as pine savannas, salt marshes, saltpans, bays and bayous as well as terrestrial habitats that are unique to the coastal zone such as maritime forests.

Healthy estuarine salt marshes and fire-maintained pine savannas are some of the most biodiverse habitats in North America, and the reserve is fortunate enough to contain considerable amounts of both. These habitats support many important species of fish and wildlife. Commercially and recreationally important species of finfish and shellfish such as brown shrimp, speckled trout and oysters abound here. Sea turtles, bottlenose dolphin and, on occasion, manatees can be found in the deeper waters of the reserve. Many species of carnivorous plants and orchids can be found in the higher savanna habitats.


caption Grand Bay Reserve administration pie chart. (Source: NOAA) The reserve operates as a functional unit within the Mississippi Department of Marine Resources (DMR) and as a component of the National Estuarine Research Reserve System (NERRS). The DMR is working in partnership with the federal agency National Oceanic and Atmospheric Administration (NOAA) to manage this cooperative program. Similar arrangements have been made throughout the NERRS to manage the other 26 sites.

Administration of the GNDNERR closely follows the guidelines established in the Grand Bay NERR Management Plan. This plan covers the broad operations of the program and is modified approximately every five years. In 2003, a Strategic Plan was developed as a condensed version of the Management Plan. Additionally, the reserve administers an annual NOAA Operations grant with specific tasks relating to provisions of the Management Plan under financial protocol established by the State of Mississippi.

The Grand Bay NERR boundaries encompass some 18,400 acres, situated in extreme southeast Jackson County, Mississippi. Ownership of lands and waters within the reserve currently include: State/County 39%, Federal 34% and Private 27%. The Grand Bay NERR has entered into cooperative agreements with NOAA, U.S. Fish and Wildlife Service and other partners relating to the operations of the reserve.

Temporary reserve office facilities are located on Bayou Heron Road, Moss Point, just north of the reserve boundaries on lands owned by the Grand Bay National Wildlife Refuge. This space is shared with refuge staff. The permanent headquarters of the reserve and refuge, which will include an interpretive center and research facilities, is scheduled to be completed on this site by the spring of 2008.


The GNDNERR was established in 1999 and has been managed ever since through a unique local, state and federal partnership designed to promote estuarine research and education within Mississippi's coastal zone and its adjacent ecosystems. The major partners of the GNDNERR include the Mississippi Department of Marine Resources, the Mississippi Secretary of State's Office, Mississippi State University, The Nature Conservancy, the United States Fish and Wildlife Service and the University of Southern Mississippi. Additionally, a Citizens Advisory Board has been established to assure that the concerns of the local citizens are adequately addressed by the Management Board.

Seventy-five percent of the property located within the reserve's boundaries is owned by public agencies. Originally, the State's portion of the Grand Bay NERR was designated as the Grand Bay Savanna Coastal Preserve. The federal portion of the reserve is made up of some of the lands that fall within the Grand Bay National Wildlife Refuge (see boundary map). This national refuge was established by the U.S. Fish and Wildlife Service in the early 1990s to protect the nation's last and largest remnant of wetland pine savanna habitat. The Grand Bay NERR is located completely within The Nature Conservancy's (TNC) Grand Bay Savanna project area. Because of the great biological significance of this area, TNC has dedicated this bioreserve as one of its Last Great Places in America. This TNC program encourages communities to protect entire landscapes, not just selected areas of high biodiversity. caption Kenny’s Island American Indian shell midden. Photo credit: Gretchen Waggy

The lands within the Grand Bay NERR are classified as either core areas or buffer areas. The core area (outlined by yellow on the above map) consists of approximately 12, 800 acres of estuarine tidal marsh, tidal creeks or bayous, shallow, open-water habitats, oyster reefs, seagrass beds, maritime forests, salt flats, sandy beaches and shell middens. These protected core lands are extremely important to the functioning of the estuarine ecosystem; and include "ecological units of a natural estuarine system which preserves, for research purposes, a full range of significant physical, chemical and biological factors contributing to the diversity of fauna, flora, and natural processes occurring within the estuary".

The buffer area (outlined by blue in the above map) consists of approximately 5,600 acres of tidal marsh, scrub shrub, pine flatwood and wet pine savanna habitats. Buffer areas are defined as "areas adjacent to the core areas that provide additional protection for estuarine-dependent species." Additionally, a small portion of intertidal marshes located adjacent to the boat ramp at Bayou Heron is also included in the buffer area. This disturbed area currently provides the only publicly-owned waterway access point within the boundaries of the GNDNERR. Properties located within both the core and buffer areas that are not currently owned by one of the partners of the reserve have been identified and attempts to secure these parcels from willing buyers are continuing.

Many of the habitats within the reserve are considered by law to be coastal wetlands. In Mississippi's Coastal Wetlands Protection Act, coastal wetlands are defined as

"all publicly-owned lands subject to the ebb and flow of the tide; which are below the watermark of ordinary high tide; all publicly-owned accretions above the watermark of ordinary high tide and all publicly-owned submerged water-bottoms below the watermark of ordinary high tide and includes the flora and fauna on the wetlands and in the wetlands."

Mississippi's coastal wetlands are important resources, not just for the state, but for the nation as well. Wetlands provide livelihoods and recreation for coastal residents and their visitors. They serve as habitats and supply nutrients for many marine species. They serve as buffer zones for hurricane protection and places of shelter for animals. Tidal marshes, a type of coastal wetland, function as filters, removing pollutants such as sewage and surface run-off which otherwise would flow into the Mississippi Sound and degrade the state's marine aquatic resources. Because of the importance of coastal resources to the state, the Mississippi Coastal Wetlands Protection Act declares it

"to be the public policy of this state to favor the preservation of the natural state of the coastal wetlands and their ecosystems and to prevent the despoliation and destruction of them, except where a specific alteration of specific coastal wetlands would serve a higher public interest in compliance with the public purposes of the public trust in which coastal wetlands are held."

This Act establishes a permitting and compliance review process administered by the Mississippi Department of Marine Resources (DMR) in cooperation with the MS Department of Environmental Quality, MS Department of Archives and History, Mississippi Secretary of State's Office and the U.S. Army Corps of Engineers. Those wishing to impact the coastal wetland must first receive permission from the DMR.

Habitat map of the Grand Bay NERR, 2007.


Cultural History within the Grand Bay NERR

caption Grand Bay Reserve freshwater wetland. (Source: NOAA)

Archeological evidence indicates that the lands within the Grand Bay NERR were occupied as early as 4,500 years ago. Early aboriginal people probably utilized the waters for fishing and the adjacent lands for hunting, gathering and refuge as evidenced by the numerous earth and shell middens that have been located within the reserve. Recent civilizations have constructed homes along the bayous, especially Bayou Cumbust, and continue to utilize the waterways for commercial and recreational fishing and recreational boating. However, many of the homes were destroyed in Hurricane Katrina, and it is uncertain at this time how many of these landowners will rebuild.

In the early 20th century, many of the pine savanna habitats that are located north of the inhabited bayou waterfront properties were disturbed when local landowners planted them as pine plantations and began suppressing the fires that were necessary for these habitats' natural development. Many of these lands have now been acquired by the U.S. Fish and Wildlife Service, and the disturbed sites are being restored to their former condition through controlled fire management.

The western border of the refuge was developed into the Bayou Casotte Industrial Park in the early 1960s. Chevron U.S.A. Oil Refinery, Mississippi Phosphate Company and the old Jackson County Airport are examples of industries that are located immediately adjacent to the reserve. In addition to operating their refinery, Chevron U.S.A. has supported and contributed to the development of the GNDNERR and maintains several hundreds of acres of conservation lands located immediately adjacent to the western boundary of the refuge.

Physiography and Geology

The Grand Bay NERR lies within the gently sloping, lower Gulf coastal plain. It is thought that the Pascagoula River once flowed through the reserve and emptied into Point Aux Chenes Bay, forming a rich delta. Sometime after the sea reached its current level, however, the river changed its course and now flows into the Mississippi Sound approximately five miles west of the reserve. This natural diversion of the river water and its associated sediments away from Point Aux Chenes Bay has led to a condition that has resulted in the retrograding (erosion) of this estuarine system. Currently, the only major channels within the NERR are Bayou Cumbust and Bayou Heron. These tidal bayous are relatively small and have slow-moving, tea-colored waters that are rich in tannins, a natural by-product of decaying vegetation.

The Grand Batture Islands located at the mouth of Point Aux Chenes Bay once formed a significant chain of islands on the southern boundary of the reserve. However, between the years of 1853 and 1950, coastal erosional forces ate away at the islands until today they are little more than giant mud lumps. Because these islands are no longer large enough to protect the bay from high winds and waves, the sensitive coastal salt marshes located along the fringe of the bay are being eroded away at an alarming rate (over 30 feet per year).


caption Grand Bay Reserve research. (Source: NOAA)

The Grand Bay Reserve has developed an active, dynamic, and extensive research program that provides scientifically-based data to inform management strategies for the conservation of critical coastal resources. The goal of the Reserve's research program is to provide a stable environment for research by staff and other investigators through long-term protection of the site to:

  1. gain greater knowledge about coastal processes;
  2. conduct studies relating to pertinent coastal management issues;
  3. collect information necessary for better management of our coastal resources and
  4. make this information available to stakeholders.

Current research and monitoring efforts by reserve staff and other researchers are focused on meeting this goal.  To date, these efforts have focused on the implementation of various monitoring programs (e.g., water quality, meteorological conditions, nutrients, nekton, marsh birds, etc.), conducting status surveys and inventories for flora and fauna found on and around the reserve, and compiling research needs and data gaps to be used in the development of a comprehensive, long-term research strategy for the Grand Bay Reserve.  A Grand Bay Reserve site characterization study was completed in 2007.

Focus Areas of the Research Program

The Grand Bay Reserve research staff has developed several focus areas over the past 10 years.  These focus areas are based in part on several elements: increased understanding of the Grand Bay ecosystem through site-focused investigations; monitoring and research needs and data gaps identified in the site profile; research issues identified through conceptual risk assessment models developed in collaboration with the Environmental Cooperative Science Center; areas of expertise of reserve staff; and opportunities for collaboration with universities, research laboratories, and government scientists. 

The Reserve has developed six broad focus-areas for research: (1) Ecological Effects of Sea-Level Rise, (2) Ecology of Tidal Marsh Vertebrates, (3) Ecology of Unique Habitats (e.g., salt pannes, shell middens, submerged aquatic vegetation beds, etc.) (4) Monitoring Ecosystem Effects of Atmospheric Mercury, (5) Coastal Plant Ecology and Mapping, and (6) Long-term Monitoring of Environmental Conditions.  Since the inception of the research program in 2001 at the Reserve, over more than 100 research projects have taken place on the Reserve, involved reserve research staff, and/or utilized data collected for the Reserve. 

Further Reading

Disclaimer: This article is taken wholly from, or contains information that was originally published by, the National Oceanic and Atmospheric Administration. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the National Oceanic and Atmospheric Administration should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.




(2012). Grand Bay National Estuarine Research Reserve, Mississippi. Retrieved from


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