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from the Gray's Reef National Marine Sanctuary Sustainable Seas Expeditions,
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Gray's Reef National Marine Sanctuary
SSE Accomplishments Report

Overview

DeepWorker surfaces after a three hours of observations at Gray's Reef.

The primary objective for the first year of the Sustainable Seas Expeditions was to characterize the reef and offshore sites for invertebrate and fish populations, paleo-archeological fossils, and loggerhead sea turtles habitat use. Data collected will be used to develop educational and outreach materials for the sanctuary and add to long-term monitoring programs. Additionally, Gray's Reef National Marine Sanctuary and the National Ocean Service used this unique opportunity to increase public awareness and appreciation for our nation's marine sanctuaries and the work of the National Ocean Service. This was accomplished through outreach and media.

Fish Assemblage Characterization of the Georgia Bight

Tom Potts from the National Undersea Research Center and Laddie Akins from Reef Environmental and Education Foundation (REEF) conducted fish surveys at Gray's Reef near shore reefs and Sapelo Scarp outer shelf reefs. A total of seven submersible dives were completed, five at Gray's Reef and two at the Sapelo Scarp reefs. Over 15 hours of qualitative video was taken to document fish, invertebrates, and substrate. Fifteen quantitative/qualitative video transects were completed to document fish communities at the two sites. Detailed analyses of the videotapes have yet to be completed.

Conducting video transect protocol tests were not attempted due to time and equipment limitations. However, pilots were able to get a better idea of the numerous challenges associated with using this new system. For instance, pilots gained considerable experience in operating the DeepWorker submersible in such a manner as to offset bottom currents. By correctly orienting the submersible into the current and applying appropriate forward and sideways thrust, pilots were able to conduct relatively fluid, timed video transects. Still to be resolved, though, are questions pertaining to camera position in relation to the sub and camera angle in relation to the substrate, field-of-view quantification, laser placement and adjustment, and incorporation of ancillary audio capabilities to augment video footage.

Day-night Activity Characterization of Gray's Reef Vertebrates and Invertebrates

Cathy Sakas in the DeepWorker documents the day-night activities at Gray's Reef.

Cathy Sakas, Gray's Reef National Marine Sanctuary marine educator, observed the changes in activity of Gray's Reef live bottom reefs from the diurnal to crepuscular and on through the nocturnal periods. One successful submersible dive was completed starting before dusk at 19:30 and ending after 23:30. Over three hours of video was collected at the sand bottom, low relief live bottom, and high relief ledge area. Since the submersible was not equipped with a low light sensitive camera, video documentation and observations where performed with the submersible lights on and were not indicative of the natural behaviour of the fish and invertebrate fauna during the night period. To better document the changes between day and night activities a low light level camera and film need to be used. The submersible light attracted a large amount of larval fish, a hammerhead shark, and black sea bass. Submersible night dives with high intensity light might be a useful tool in collecting large samples of larval fish and will be considered for future projects. Bioluminescence of ctenophores and unidentified sessile invertebrates were observed during periods when all lights were turned off inside and outside the submersible.

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Comparative Characterization of Live Bottom Fauna in the Gray's Reef National Marine Sanctuary

Gray's Reef is know for its great diversity in sponges.

Live bottom reefs are the primary habitat on the continental shelf on the Southeastern U.S., which support dense assemblages of sponges, corals, and other invertebrates. These dense invertebrate assemblages in temperate regions form complex benthic communities that provide habitat for a great diversity of associated species, many of which provide direct food resources for commercial and recreational fish species. The composition and structure of macro-benthic communities influence the spatial heterogeneity of resource and refuge patches for many of these economically important fish species. A thorough understanding of benthic fauna assemblages and diversity of hard bottom reef communities is essential in determining the capacity in which reefs function as habitat for economically important fisheries. Although no dives were solely dedicated to this project during this years investigations, video documentation from other dives will be analyzed for invertebrate species composition.

Alex Score in the DeepWorker takes visual counts of invertebrates at Gray's Reef.

Submersible cameras were critical for the success of this project since good close video transects are imperative for accurate identification of species. Unfortunately, during the Sapelo Scarp dives one of the cameras malfunctioned and did not have good color or resolution for the analysis of invertebrate fauna. Other video footage taken at Gray's Reef will be analyzed and used in conjunction to photo-quadrats and video transects currently used in Gray's Reef invertebrate fauna monitoring program.

Paleoenvironments and Archaeology at Gray's Reef

This project is a continuation of research at Gray's Reef that has (1) discovered scientifically significant fossilized remains of nearly 12 extinct mammals from the last glacial period- the Pleistocene; (2) obtained core and shallow excavation samples of previously unexplored buried land surfaces that have been shown to contain plant remains of a paleoecology associated with the extinct animals; and (3) begun construction of paleoenvironmental/ paleoclimatological model for the late Pleistocene based on these data obtained from our undersea research. A total of three dives with approximately four hours of observations were completed covering over six miles of sand-bottom habitat at Gray's Reef. A systematic transect search method was employed running North/South transect for 15 minute intervals. One fossil was observed during the search that seemed to have been from a large mammal, probably the leg bone of a bison. Unfortunately, the manipulator arm in the submersible was not functioning so the fossil sample could not be collected for further testing. The submersibles proved to be a good searching tool for large areas and will be used again for this project.

Tom Potts and Tom Zemianeck record DeepWorker's life support readings and monitoring through-water communications from the chase boat.

Sea Turtle Population Survey

No submersible dives were made for this project but turtles were observed on two of the submersible dives. Turtles were observed swimming and feeding in the high relief live bottom habitat and sleeping in the sand flats area. More dedicated dives with systematic searches will be required for this project.

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