Gray's Reef National Marine Sanctuary
Gray's Reef National Marine Sanctuary
Data Buoy Science


A variety of efforts to characterize the resources within Gray's Reef have been undertaken by NOAA and others. These efforts are designed to understand the biodiversity, habitats, resources and ecological processes controlling the environment. Site characterization also describes the history of the site, resource protection efforts, effects of human activities on natural systems and socioeconomic information. Site characterization is the process of identifying and assessing the natural and cultural resources of interest within a sanctuary. Establishing a baseline of the status of resources is critical for later evaluation of the impacts of natural events and human activities, and the effectiveness of management strategies. The following describes some of the characterization efforts that have been undertaken in Gray's Reef NMS.

Seafloor Characterization

Studies to map the seafloor have been conducted at Gray's Reef by the United States Geological Survey, the NOAA National Center for Coastal Ocean Science, Coastal Carolina University and others. Results from these surveys have given us a three-dimensional image of the bottom topography in the sanctuary, and illustrate the habitat diversity and complexity. Diver observations were used to "ground-truth" the sonar signals, to help us interpret what kinds of bottom formations and animals are associated with features noted on the sonar images. This has enabled us to build a geographically-referenced image of the bottom and different kinds of habitats. Gray's Reef is composed of four main bottom types: flat sand, rippled sand, sparsely colonized (by attached sponges, corals and other invertebrates) live bottom, and densely colonized live bottom (ledges). The four bottom types have distinct physical and biological characteristics.

Fish Assemblages

Dr. Matt Kendall conducted a study to characterize fish assemblages and their relation to habitat types. Dr. Kendall found that habitat is a significant factor in determining the types of fish found in a given area. High-relief ledges have many individuals and kinds of reef fish, whereas sand habitats have fewer individuals of only a few species. Fish diversity and abundance of fish were positively related to total percent cover of sessile invertebrates and ledge height. For additional details on bottom type, habitat and species distributions and characterization, click here. NOAA Technical Memorandum NOS NCCOS 50. 82 pp. (4361 kb)

Recruitment and Succession of Sessile Benthic Invertebrates in the South Atlantic Bight

Dr. Danny Gleason at Georgia Southern University is working inside and outside of Gray's Reef National Marine Sanctuary to determine the recruitment and succession of sessile benthic invertebrates. Sessile benthic invertebrates are organisms that settle and attach to the seafloor, such as sponges and corals. Dr. Gleason is studying which invertebrates settle first to newly available substrate. He is also interested in determining the recruitment rate, death rate and growth rate of settled organisms. For more information on this project please visit Dr. Gleason's website.

Sponge and Octocoral Epifauna at Gray's Reef National Marine Sanctuary

In 2008, College of Charleston graduate student Anna Greene completed a Master of Science thesis titled "Invertebrate Endofauna Associated with Sponge and Octocoral Epifauna at Gray's Reef National Marine Sanctuary off the Coast of Georgia." With aid from her thesis advisor, Jeff Hyland, and scientists from Gray's Reef, Ms. Greene conducted a study to characterize invertebrates that are found around and within soft corals and sponges that are found on the live bottom habitats of GRNMS. This study has provided information about the importance of sponges and soft corals at GRNMS and information about the invertebrate species found in GRNMS. To view the publication about this project click here.

Please visit the Publications section of our site to learn more about research that has been conducted in Gray's Reef National Marine Sanctuary.

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