Gray’s Reef awash with life off Savannah’s coast

Expedition aboard NOAA ship studies invertebrates, predator-prey relationships

To the naked eye, there’s not much to Gray’s Reef National Marine Sanctuary.

 

The 22-square-mile swatch of federally protected ocean looks, on the surface, like the rest of the deep blue sea off Georgia’s coast — distinguishable only by a large, bright yellow buoy adorned with solar panels.

But underneath the surface, vibrancy pops.

The sanctuary is as warm with life, with loggerhead sea turtles, black sea bass, nurse sharks and even the occasional North Atlantic right whale calling it home. The live bottom reef itself sits about 60 feet under water, and its rocky seafloor makes a comfy habitat for invertebrates like sea squirts, sponges and anemones.

While anchoring is prohibited in the sanctuary, rod and reel fishing and diving are allowed. It’s also, naturally, something of a haunt for local scientists, especially those working out of the National Oceanic and Atmospheric Association-run sanctuary’s headquarters on Skidaway Island and the adjoined Skidaway Institute of Oceanography, an arm of the University of Georgia.

NOAA and UGA scientists make regular trips to the sanctuary, but it’s about 40 miles off Savannah’s coast. As Kimberly Roberson, the sanctuary’s research coordinator, puts it, that’s a two-hour commute to the “office.”

One of Skidaway Institute’s boats, the Research Vessel Savannah, has onboard labs and can make longer trips, but the big expedition comes in the summer with a little help from the NOAA Corps.

For about two weeks each year, Gray’s Reef scientists and others from around the region are able to board the NOAA Ship Nancy Foster, a 187-foot vessel for an extended stay at the sanctuary.

“Everyone within NOAA competes for NOAA ship time, and we’ve been fortunate for the past several years to get two weeks out at Gray’s Reef,” Roberson said aboard the Nancy Foster last month. “It’s our main concentration of research, and the principal investigators count on that time to conduct their research every year.”

Last month’s expedition brought together scientists from NOAA’s Marine Fisheries Service and Center for Coastal Ocean Science, the University of Connecticut, Georgia Southern University, Valdosta State University, Louisiana State University and the National Marine Fisheries Service.

“This allows us to have a concentrated, devoted time,” said Roberson, who served as chief scientist for the expedition.

The Nancy Foster has a full-service kitchen, living quarters and labs for scientific research. Its ability to carry and launch smaller vessels also gave the scientists an added benefit in terms of their ability to explore and gather information.

“We can get in five to six dives a day,” Roberson said.

On the trip, researchers dove and conducted sampling in support of invertebrate studies and fish surveys. As part of the observational process, they placed cameras underwater at 20 sites in the sanctuary in an effort to photograph invertebrates living on the bottom and other sea life.

Gray’s Reef’s shifting sands provide what Roberson called a “dynamic” habitat full of ridges and shelfs.

“These ledges are really important areas where fish congregate,” Roberson said. “It’s an interesting feature for them. It provides them habitat, it provides them food, it provides turtles resting places. So, other fish and other members of that community pop in and see who’s there and what’s going on.”

Another major endeavor was studying predator-prey relationships to determine whether prey resources vary over night and day at reefs and whether predators and prey interact differently at and away from reefs.

Scientists also conducted sonar surveys to study biomass and fish density.

“We use this technology because it allows us to cover a lot of space compared to scuba diving,” Fabio Campanella, a postdoctoral fellow at NOAA’s Ocean Service lab in Beaufort, N.C., said of the scanning capabilities aboard the Nancy Foster. “We gather the information to have a better picture of the system.”

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