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NOAA Projects

Integrated Ecosystem Assessment

Deep-Water Coral Investigation with University of Puerto Rico

NOAA has provided a grant to the University of Puerto to conduct a characterization of the shallow and deep coral reef communities in Vieques, Puerto Rico .  While several studies have been conducted on the condition of shallow-water coral reefs within the bombing impact zone, there is little information on the condition of the deep coral reefs of Vieques. For the most part, the distribution, health, and community structure of deep hermatypic (zooxanthellate) coral reefs in Vieques and elsewhere in the U.S. Caribbean remain largely unknown. There is no available information on the possible impact of the military activities on the deeper reefs that are present within the danger zone limit established by the U.S. Navy for the eastern part of Vieques Island .

Dr. Roy Armstrong, University of Puerto Rico , will conduct benthic surveys of shallow (10 m) to deep (30-40 m) coral reefs present on the south coast of Vieques using the Seabed autonomous underwater vehicle (AUV) and a remote operated vehicle (ROV). Two 3-4 Ian long photo transects will be obtained by the AUV in order to assess the condition of the reefs as a function of distance from shore, where the bombing range was located. An additional AUV transect will be obtained from El Seco, a deep reef 9 Ian east of Vieques, which will be used as a control.  The AUV transects will provide the quantitative data required to ascertain the possible direct physical damage by exploded and unexploded ordnance as well as other pollution sources as a function of the depth of the reefs and their distance from shore. Shorter 10-20 m long video transects will be obtained by the ROV to supplement the AUV data. The location of all transects will be established in coordination with NOAA, who will be conducting benthic surveys in this area.

The main objectives of this research are:

• Assess the condition and percent substrate cover of coral reefs found from shallow-water (10 m) to more than 40 meter depths on the south coast of Vieques Island.
• Provide a quantitative description of substrate cover by sessile-benthic categories from ROV video transects and A UV photo transects as a function of depth and distance from shore. The major sessile-benthic categories include corals, sponges, gorgonians, macroalgae, sand, bare substrate, and seagrass.
• Document the condition of the reefs and other benthic communities in terms of observed physical damage, living versus dead coral cover, diseased corals and bleached coral reef organisms. 
• Compare the condition of the deeper reefs within the danger zone south of Vieques to a control reef, at a similar depth, 9 km east of the impact area.

Methodology

The Seabed AUV

The AUV was designed to operate up to 2000m depth to carry out photo transects, sidescan/multibeam sonar and bathymetric surveys. A Pixelfly 1024 x 1280 pixel resolution CCD camera, with 12 bits of dynamic range, is the primary optical imaging sensor. A 150 watt-second strobe is used for photographic illumination. The strobe is mounted 1.4 meters aft of the camera to reduce the effects of lighting backscatter in the images.  Measurements of velocity over the bottom, heading, altitude, pitch, roll, and integrated position are provided by a 300 kHz Acoustic Doppler Current Profiler (ADCP), which projects four sonar beams into the water. The AUV is programmed to maintain a fixed distance from the bottom to avoid collisions in case sudden changes in bottom relief are encountered. The distribution of the four thrusters, coupled with the passive stability of a two-hulled vehicle with a large meta-centric height (Figure 1), allows the Seabed to survey close to the sea floor, even in very rugged terrain and to follow a greater than 450 slope. As opposed to most other AUV's, the Seabed was designed to be hover capable, that is, to be able to independently drive in the X,Y and Z axes.

The expected timeframe for the AUV cruise is December 2006 to January 2007. The three Vieques transects will be obtained as part of a larger survey of deep reefs of Puerto Rico and the U.S. Virgin Islands.

ROV

A Seabotix LBV-150, depth rated at 150 m, will be used for the ROV video transects. This ROV is equipped with a 570 Line/0.2 Lux color camera, a 430 Line/0.03 Lux black & white camera, internal LED and external lights, a laser scaling system, a manipulator arm with a three-jaw and parallel grabber, and a digital video recorder. Since this unit requires AC power it will be operated from a chartered vessel during a one-week period in November 2006.

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