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from the Flower Garden Banks National Marine Sanctuary Sustainable Seas Expeditions,
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Flower Garden Banks National Marine Sanctuary SSE Accomplishments Report

On August 29, DeepWorker pilots Steve Gittings, Edie Widder, Peter Vize, and Emma Hickerson departed Key West on board the NOAA Ship Ferrel and steamed towards the Flower Garden Banks National Marine Sanctuary. Flat, calm seas and dolphin and whale spottings brought hopes for good weather during the missions. Unfortunately, the sea state took a downward turn about the time the Flower Garden Banks hit the radar screen. Although faced with unpredictably bad weather, and certain logistical problems, a total of 12 DeepWorker dives were conducted in the short time nature cooperated.

Coral Spawning

A remotely operated vehicle is deployed to document spawning. Weather and sea conditions did not permit scuba or DeepWorker dives to be conducted during this event. (Photo credit: FGBNMS)

On the peak spawning night for several species of coral, scuba and submersible operations were canceled due to weather conditions and sea states. Fortunately, an S2 Phantom remotely operated vehicle (ROV) could be deployed to document this event. Phil Otalora, Nuytco, flew the ROV for several hours as others crowded around the screen to witness the beauty of the "snowstorm" occurring beneath the water. Dr. Peter Vize, the principle investigator of the coral spawning project, made several good observations using the ROV as his window to the spawning. He recorded the deepest spawning observation to date, Montastraea cavernosa (a star coral) at 43 meters.

Unfavorable sea states disrupted submersible diving operations for the remainder of the first week, so scuba and ROV operations were continued. Spawn collections were made using scuba. Samples from blushing star coral, Stephanocoenia sp., verified that this species' eggs are fertilized prior to release from the female coral.

Geological Exploration

Emma Hickerson, research coordinator for the sanctuary, prepares for a dive. (Photo credit: Frank Burek)

During dives, DeepWorker pilots reported changes in topography to topside. The vertical incline of the reef crest on the west bank varied from around 50-80 degrees. Some portions were densely covered with well developed boulder and star corals. In other areas, it was clear that the reef had collapsed and toppled down to the sandy bottom. What was left was just rubble. On two occasions, pilots Emma Hickerson and Laddie Akins observed small canyon like formations with reef structures forming the canyon walls. These areas had sandy bottoms, as if some force had been moving down the crest like a river. Emma and Laddie followed the "rivers" up to 90 feet (30 m) to a sunken "bowl" shaped depression, approximately 30 feet (10m) across, with the "river" of sand forming a horseshoe around the top side, and returning down the crest on the other side of the "bowl". In the middle of the depression was well formed reef - star and brain coral - just lower than everything around it. This area appeared to have sunk, probably due to dissolution of the salt dome underneath. Hence, somewhere below, a brine seep like that on the east bank may exist.

On the east bank, Jim Gardner and Dave Lott used technology provided by the U.S. Geological Survey to navigate the ROV to points of interest in and around the brine seep. The ROV was also used to explore the north ridge of a graben area. The U.S. Geological Survey mapped the Flower Gardens in the winter of 1998 using high resolution multibeam sonars. The images were taken originally to test equipment but were spectacular and informative, stimulating further interest. A paper on this work was published in the recent dedicated issue of the journal Gulf of Mexico Science (for copies, email emma.hickerson@noaa.gov).

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Fish Censuses

The nurse shark (G. cirratum) was one of several shark species seen during the Expeditions. (Photo credit: Frank and Joyce Burek)

Emma and Laddie simultaneously piloted the two DeepWorker submersibles while conducting REEF (Reef Environmental Education Foundation) censuses of the fish they encountered in different zones. They began their surveys in the zone where the coral stops, between 150 and 170 feet (50-57 m). Red hind (Epinephelus guttatus), not often seen on top of the reef crest, were abundant, propped up on their pectoral fins on top of coral heads. A dynamic school of cottonwick (Haemulon melanurum) congregated in a particular location of the reef edge and it was realized that it was a large cleaning station. Numerous juvenile Spanish hogfish (Bodianus rufus) flitted around the school cleaning one fish, then the next. A large school of horse eye jacks (Caranx latus) took time out of their transit to swirl several times around Laddie's submersible. Emma recorded a total of 40 fish species during her survey around this small portion of the base of the west bank, including sunshinefish (Chromis insolata), large amberjack (Seriola dumerili), tiger grouper (Mycteroperca tigris), and green razorfish (Hemipteronotus splendens). Several carcharinid sharks were seen, but their species could not be identified.

Next Laddie and Emma headed west over the sand, which was filled with yellow-headed jawfish (Opistognathus aurifrons) dancing over their holes. As they descended, the terrain changed to rubbly chunks of drowned reef. Several very large circular piles of rubble revealed large sand tile fish (Malacanthus plumieri) busily picking up chunks of the rubble and moving the rubble to the perimeter of their territory. With continued descent, the rubble turned to algal nodules, hiding all sorts of cryptic species. Emma hopes to return to this zone next year to collect some of these nodules to assess the contents -- likely micromolluscs, sponges, etc. The deepest depth reached by Emma and Laddie was about 260' (87m) where there were large outcroppings. A roughtongue bass (Holanthias martinicensis) was seen among the outcroppings.

Tiger grouper, Mycteroperca tigris, and several other grouper species were seen around piles of reef rumble, perhaps preferred habitat. (Photo credit: Frank and Joyce Burek)

On another DeepWorker dive, Emma and Laddie circumnavigated the west bank crest at 150-170 feet (50-57 m) and while surveying fish using the REEF roving diver technique they noted a healthy population of groupers -- tigers (Mycteroperca tigris), yellowmouths (M. interstitialis), blacks (M. bonaci), and yellowfins (M. venenosa) -- and a comb grouper (M. rubra), rarely seen on the east and west banks. Piles of reef rock, which had perhaps tumbled from the reef crest, seemed to be the preferred habitat for groupers. About a half dozen reef sharks were also observed in the area. Forty fish species were recorded during the dive.

One limitation of the DeepWorker, discovered during REEF roving diver surveys, is that it cannot get close enough to the substrate to allow the pilot to see the cryptic species.

Georeferencing

One of the major accomplishments of the missions at the Flower Garden Banks was the use of the tracking system. This system allowed pilots and topside technicians to georeference notable observations, such as the cleaning station with the cottonwicks, an anchor, a cable, or a particularly large congregation of grouper, so that in future expeditions pilots and scientists will know where they have been and what to look for.

This water spout was only one of the weather hazards that plagued the Expeditions during its first week at the Flower Garden Banks National Marine Sanctuary. (Photo credit: FGBNMS)

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