Sea Technology

JUN 2018

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

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18 ST | June 2018 Dr. Mark Borrel- li is the director of the CAPE Lab. His research interests include coastal sed- imentary processes, seafloor and benthic habitat mapping, and understanding how storms, sea level rise and anthropogenic impacts affect the coast. Bryan Legare, M.S., is a marine research- er at the Center for Coastal Studies. His research interests in- clude benthic habitat mapping, fish move- ment and habitat use, and marine habitat assessments. He spe- cializes in technical field operations of data loggers, monitoring in- struments, survey equipment and biologic sam- pling in the marine environment. Theresa Smith is a research geologist and hydrographer at the Center for Coastal Studies. She is inter- ested in the physical processes of coastal and marine environ- ments, nearshore geomorphology, bar- rier spit evolution, and understanding littoral systems with respect to sea level rise and increasing storm intensities of the northeast U.S. coast. Cape Cod, in southeastern New England, is a glaciated coast, and these finer-grained areas are likely outcrops of more erosion-resistant glacial material. The bathymetry alone would still allow for identi- fication of targets that may or may not be lobster pots, but the bathym- etry coupled with the side scan im- agery is determinative and together provides information not attainable with either data set alone. Some of this derelict fishing gear has been submerged for decades and now provides habitat for aquat- ic life. Scuba divers were used to collect information about the state of the gear and surrounding habitat, collect images and video and sedi- ment samples, and aid in retrieval. Combining diver and acoustic sur- veys has provided useful informa- tion to ascertain the habitat value and extent with regard to derelict fishing gear, as well as ground-truth- ing the acoustic data. Coastal municipalities are per- forming more nearshore resource assessments in order to balance the economic drivers of coastal and ocean tourism with responsible stewardship of these ecosystems. Keeping shallow navigation chan- nels open while avoiding protected submerged aquatic vegetation (SAV) is difficult to perform and docu- ment. Typically, one would collect bathymetry to do a pre-dredge sur- vey in a navigation channel or a traditional side scan sonar to map eelgrass beds, however, when both were needed, the PMSS allowed one survey to collect both co-locat- ed data sets. The Town of Chatham, Mas- sachusetts, was concerned about maintaining a heavily used, shallow navigation channel and potential impacts to eelgrass beds. A shal- low-water survey was done August 2017, and the eelgrass beds were clearly identified on the side scan imagery, as well as in the bathym- etry. The identification of the SAV as eelgrass would have been prob- lematic with only the bathymetric data, and a pre-dredge survey with a side scan sonar would not provide the 3D data needed. These co-lo- cated data sets also provide useful information with regard to sediment transport pathways (erosion and ac- cretion), anthropogenic impacts to SAV, and other issues of interest to managers. Coastal resources are under in- creasing pressure from develop- ment, tourism and competing uses. These stressors are compounded given the current regime of cli- mate change and projected rates of sea level rise and the increasing frequency and magnitude of coast- al storms. Mapping these extreme shallow water environments pro- vides much needed quantitative, spatial data to develop largely un- available baseline inventories of these resources but also to measure future change in a rigorous and repeatable way. Phase-measuring side scan sonars coupled with shal- low-draft survey platforms is one way to collect these data rapidly, efficiently and safely. ST www. 25 rue Michel Marion 56850 Caudan - France +33 (0)297 898 580 - UNDERWATER LISTENING SYSTEMS New Noise Processing Features Versatile Acoustic Recorders Real-Time Listening Remote Buoys 26-28 June 2018 SEC, Glasgow Find us at stand E42

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