EK60 Water Column Sonar Data Collected During HB0904

Habitat Mapping Cruise - Hudson Canyon (HB0904, EK60). Objectives are to: 1) perform multibeam mapping of transitional and deepwater habitats in Hudson Canyon (off New Jersey) with the National Institute of Undersea Science and Technology (NIUST) AUV Eagle Ray. About one half of the shelf portion of the canyon was mapped with Eagle Ray between 2007 aboard Ronald H. Brown and 2008 aboard Henry B. Bigelow. We seek to complete the mapping of the shelf segment of the Hudson Canyon on this cruise; 2) perform visual ground truthing of areas up to 1,000 m deep in Hudson Canyon using the NIUST AUV Mola Mola. In particular, we will be investigating ravines in canyon walls mapped by Eagle Ray for vulnerable deepwater coral and sponge communities, tilefish pueblo villages, and suspected areas of methane blowouts in the canyon bottom for vulnerable chemosynthetic communities. Such vulnerable communities may be at risk due to overlap with deepsea red crab, witch flounder, and/or monkfish distributions. The intention is to detect and locate vulnerable communities and also to gain experience for development of protocols for further exploration for vulnerable deepwater habitats in canyon and slope areas; 3) perform a series of CTD/rosette sampler casts down the canyon to a maximum depth of about 1,200 m in the canyon axis. This will provide a near-synoptic, 3-dimensional view of water mass interaction around Hudson Canyon and allow collection of water samples at multiple depths for dissolved methane analysis. The latter will help resolve the source of elevated methane previously detected in deep water within Hudson Canyon. Possible discovery of a local seep raises the possibility of a chemosynthetic community supported by that feature; and 4) collect ME70 multibeam sonar data for purposes of benthic mapping in order to resolve some issues encountered during summer 2008 cruises for that purpose.