Sea Technology

JAN 2013

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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sippi Canyon Block 118 (MC-118), located within 20 miles of the Macondo well blowout. The second multisensor array, the Gulf Hydrocarbon-ANDI or GHANDI, was deployed in June 2010 at Conch Reef in the Florida Keys to survey and detect the spatial variability in background light hydrocarbon distributions in local waterways and along the outer-reef track. The GHANDI array was designed as a survey instrument to be attached to rosettes, ROVs or submersibles. It features fast-response optodes and multiple sensors to monitor CTD, oxygen, light hydrocarbons and current conditions. With the platform's four analog input channels, the team can also select from other commercially available sensors, such as those for methane and other light hydrocarbons used in oil spill monitoring efforts. This system has allowed the scientists to adapt the sensor suite confguration to meet the demands of each stage of the program by combining, adding, removing and redistributing sensors or strings within minutes. Collecting Reef Water Data UNC scientists collected continuous oxygen and temperature data along with the background oceanwater data on a living coral reef in the Florida Keys for nearly three months using an array based on the AADI Seaguard String, Reef-ANDI, or RANDI. The team made synchronized observations with RANDI in a reef ecosystem in search of mechanisms affecting the functions and health of organisms, while monitoring and controlling environmental parameters. The system allowed simultaneous monitoring and logging of ambient dissolved oxygen along with multiple in-situ benthic respiration measurements. Equipped with a 170-meter-long string and 11 fast-response optode sensors, the RANDI array collected data every 30 seconds and sent information via radio to onshore laboratories in near real time, continuously monitoring ambient dissolved oxygen concentrations and benthic respiration on the seafoor. Respiration measurements were obtained using fve pairs of sensitive optode oxygen sensors, spaced at 30 meter intervals along the main trunk cable or "string," which were located at depths of 16 to 24 meters along Conch Reef off Key Largo during summer 2010. This sensor confguration featured two groupings of smart sensors on one instrument, one set of six on the pressure vessel and a second set of 10 distributed remotely across a 170-meter-long cable. This confguration was made possible through the onboard CAN (controller area network) bus sensor network interface. By using wet-mate connectors, each of the remote sensors was mounted independently on a 3-meter fy cable. The individual sensors could also be removed or replaced underwater for cleaning or other maintenance. In addition to ambient dissolved oxygen concentrations and benthic respiration monitoring, the instrument can also measure CTD, and current speed and direction. The UNC HANDI AADI Seaguard logger platform. long lasting. UNC scientists have developed new systems to facilitate effcient detection of light hydrocarbons and oxygen depletion associated with oil and gas releases. Such long-term deployments are needed to provide important new information about the processes controlling rapid changes now threatening reef ecosystems around the world. n Dr. Chris Martens, professor of marine sciences at the University of North Carolina at Chapel Hill, was awarded a Ph.D. in chemical oceanography from Florida State University and a National Science Foundation postdoctoral fellowship at Yale University. He has led numerous surface ship, submersible and Aquarius saturation dive missions, following research interests in sensor technologies for deep-sea and coastal time-series studies. Richard Butler, group manager at Aanderaa Data Instruments, is a graduate of Massachusetts Maritime Academy where he earned a bachelor's in marine engineering and a U.S. Coast Guard Third Engineer License before retiring as Lt. Cmdr. of the U.S. Navy Reserve. He also served for six years on the board of directors for the Marine Technology Society. Conclusions Even small oil spills can severely affect marine life and the surrounding environment, and the effects can be very 52 st / JANUARY 2013 www.sea-technology.com

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