EK60 Water Column Sonar Data Collected During HB0806

Habitat Mapping Cruise - Tunicates (HB0806, EK60). Objectives: Use otter trawls (if available), beam trawls (if not), Naturalist Dredge, SEABOSS photography/bottom grab equipment, CTDs, and large (10-30 liter) Niskin water bottles and ship’s ADCP to conduct the following operations: 1) determine changes in distribution and condition of invasive colonial tunicate Didemnum vexillum on northern Georges Bank gravel habitat, and also northeast of Great South Channel; 2) document the influence other ecosystem components, substrates, hydrology, and disturbances, including fishing disturbances on tunicate-benthic/demersal stock interactions; 3) collect tunicate specimens for further study including DNA analysis, and collect near-bottom water samples in tunicate areas; 4) explore the function of a newly-discovered benthic/demersal community not influenced by trawling or tunicate colonization, 5) continue monitoring recovery and productivity of untrawled gravel habitats in HAPC on northeastern Georges Bank, as compared to nearby trawled habitats; also, time permitting, and 6) re-occupy existing stations and sample new stations on a transect from the northeast corner of NLCA to outside the eastern boundary of NLCA.