Gray's Reef National Marine Sanctuary
Gray's Reef National Marine Sanctuary
2017 Gray's Reef Research Cruise Photos
Mission Information

Gray's Reef Research
Expeditions 2017

Sunday: June 18, 2017
Log Day 10

Jody Patterson
Gray's Reef Events & Volunteer Coordinator
Savannah, GA

Sponge and coral grouping.

Sponge and coral grouping.
(Photo: Alicia Reigel, LSU)

Gray's Reef has long been known for its' fish communities by local anglers who have enjoyed the abundance of snapper, grouper, mackerel and other tasty or elusive species found here. Just this weekend we observed a number of fishing vessels in and around the sanctuary while a kingfish tournament was underway, yet many anglers are unfamiliar with the habitat below that draws such diversity to it.

Today, our scientists wrapped up their surveys to determine abundance and diversity of sessile invertebrates (spineless animals attached to the seafloor) found inside the open areas of the sanctuary compared to the research only area. NOAA established a research area in Gray's Reef to increase the opportunity to witness natural ecological changes within the sanctuary versus changes caused by humans. The researchers did indeed note changes throughout all areas of the sanctuary; however, these seem to be ecological in nature.

Seafloor invertebrates are possibly key to the wealth and abundance of fish at Gray's Reef as they offer food, hiding places and other important functions. The researchers responsible for studying these invertebrate communities during our cruise this year are Georgia Southern University's Drs. Danny Gleason and Risa Cohen, graduate student Brianne Varnerin, and PhD student Alicia Reigel from Louisiana State University. This team studies the animals, plants, and microbial residents of the seafloor, and various members of the Gleason lab have been surveying the sanctuary since the summer of 2011. What they are finding this summer is proving to be a different story than what they have witnessed before.

Telesto species.

Telesto species.
(Photo: Brianne Varnerin, GSU)

Encrusting along the tops of reef ledges and scattered throughout the sand there are usually high numbers of tunicate, sponge and octocoral species. The brightly colored octocorals grow together in mass colonies, some on long stalks that appear to shiver in the swift water currents. One such octocoral found during this mission in Gray's Reef is Telesto. Two species of Telesto are normally found in the sanctuary; however, this year researchers have recorded a third very distinct species. This Telesto species may be new to Gray's Reef, has very bright, white polyps, and looks much like a flower underwater. Dr. Gleason received permission to collect a sample of the unknown species and his colleague Alicia Reigel will sequence its DNA later to identify it. This was one bright spot in their otherwise unusual survey results.

Gleason, who has studied Gray's Reef for 15 years, seemed less than pleased to note that many of the sites they visited the past week had fewer tunicates than he hoped but more leafy algae in its place. He noted that the ledges appeared scoured by sand and current, which could have removed the delicate animals from the seafloor.

Sandy-sediment filled terrain .

Sandy-sediment filled terrain.
(Photo:Brianne Varnerin, GSU)

These oceanic factors are always prevalent, so why would this summer's survey look different from last? My gut instinct tells me it probably has something to do with a little storm that blew through in October 2016 named Hurricane Matthew. This immensely strong low-pressure system wreaked havoc along the eastern seaboard with measured wave heights of 19 feet at the Gray's Reef buoy before the instrumentation broke. The seafloor may have experienced similar conditions as the surface waters during this storm event, which could prove to be a major factor in the reduction of seafloor invertebrates such as tunicates. The buoy has since been repaired and is collecting data to inform visiting anglers and divers of current sea conditions, however the benthic community will take time to resettle, grow and populate the otherwise thriving ecosystem below.


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