Sea Technology

SEP 2012

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

Issue link: http://sea-technology.epubxp.com/i/82362

Contents of this Issue

Navigation

Page 42 of 91

These studies also presented the opportunity to explore some of the technical questions related to glider work. Shelf- edge reef topography complicates deployment at Pulley Ridge, as do highly variable currents and water density. Strong currents at the western edge of the ridge presented difficult conditions for the slow-moving glider. However, the strategy of minimizing the time the glider spent on the surface proved effective in making headway despite the currents. To obtain profiles within several meters of the seabed, the survey team used previously acquired multibeam bathymetry to assist with setting maximum dive depths. Because the entire mission took place in the euphotic zone, the effects of biofoul- ing on the glider and sensors were also a concern. Indeed, it was evident that the sensitivity of the optical sensors was significantly reduced by biofouling after more than six weeks. These separate sorties enabled assessment of seasonal changes in chlorophyll distribution, turbidity, salinity and temperature structure above the reef and in surrounding wa- ters. During the attended phase of the first mission, benthic video survey, CTD rosette profiling and plankton net trawls were also performed in the vicinity of the glider. The chlorophyll maxima over Pulley Ridge was quite consistent between the fall and winter sorties, ranging from 1 to 1.3 micrograms per liter at 50 to 55 meters water depth. In contrast, the temperature and salinity structure was highly variable between the two missions and was most evident in a salinity inversion observed in the February 2012 data. Future Work These missions demonstrated that the Spray Glider is a capable, cost-effective means of monitoring distributions of chlorophyll, turbidity, temperature and salinity structure at shelf-edge mesophotic reef ecosystems. The longer term outcome of these missions could be the use of gliders as tools to indicate the presence and health of deep coral ecosystems by measurement of larval and plank- ton populations in the adjacent benthopelagic region. An- other mission to Pulley Ridge was scheduled for September to November 2012, with plans to pilot the glider toward deeper water to the southeast where other deep coral reef ecosystems are known to exist. n Dr. Fraser Dalgleish directs the Ocean Visibility and Optics Laboratory at Harbor Branch Oceanographic Institute. His research emphasis is on undersea optical sensor develop- ment for remote and in-situ environmental measurements and the improvement of sensing and communications capa- bilities as an enabling technology for multivehicle surface- to-seabed imaging and sensing operations. John Reed is a senior research scientist and research profes- sor heading the Robertson Coral Reef Program. He has or- ganized and supervised 60 expeditions worldwide that have resulted in the collection of more than 30,000 marine speci- mens. His research specializes in the biology of deepwater reefs and taxonomy of reef organisms. Dr. Tammy Frank is an associate professor at Nova Southeast- ern University. Her research focuses on how light controls the distribution pattern of midwater animals, functional ad- aptations of photoreceptors to different light environments, and linkages between pelagic and benthic habitats. www.sea-technology.com SEPTEMBER 2012 / st 43 SEE US AT OCEANS '12—BOOTH #1908

Articles in this issue

Links on this page

Archives of this issue

view archives of Sea Technology - SEP 2012
loading...
Sea Technology