Gray's Reef National Marine Sanctuary
Gray's Reef National Marine Sanctuary
Gray's Reef Expedition 2012
Mission Information
 

Invertebrate Density & Abundance

During the 2012 NOAA Ship Nancy Foster cruise, Dr. Daniel Gleason and Dr. Risa Cohen from the Department of Biology at Georgia Southern University, assisted by students James Price and Brittany Poirson, will document the diversity and abundance of bottom-dwelling invertebrate populations occupying ledge outcrops inside and outside the proposed research area at Gray's Reef National Marine Sanctuary.

Livebottom and sponges

Livebottom and sponges
(Photo: Greg McFall, GRNMS)

Bottom habitats of the Georgia continental shelf consists primarily of soft substrate such as sand, however, rocky outcrops covered with algae and non-mobile, bottom-dwelling invertebrates comprise approximately 20 percent of the bottom. These rocky reefs support a diverse array of invertebrates as evidenced by Gleason's collections documenting over 325 species of sponges, corals, sea stars, sea squirts and other animals.

Short spined sea urchin

Short spined sea urchin
(Photo: Greg McFall, GRNMS)

Even more striking for the region is the fact that over 80 of the specimens collected to date represent new records for the area. For sponges alone, of the 52 species identified, 15 represent new records for the area, nine were previously reported exclusively from tropical habitats and eight from temperate areas.

Not only are these "livebottom" reefs diverse, but they improve fish harvests and diversity by aggregating animals, providing valuable food resources, and supplying critical habitat by enhancing structural complexity. Interestingly, our understanding of the dynamics of the organisms providing much of the complex structure of these rocky habitats, the bottom-dwelling invertebrate community, is poor.

Soft coral

Soft coral
(Photo: Greg McFall, GRNMS)

During the cruise Gleason and colleagues will document the abundance and diversity of invertebrate populations occurring along rocky ledges found within Gray's Reef. Collecting this data is critical to our continued efforts to asses the effects of the recently established no-take research area within the sanctuary.


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