As part of the U.S. GLOBEC NW Atlantic/Georges Bank study, Dr. Wiebe and collaborators will determine the broad-scale distribution of zooplankton and nekton populations on Georges Bank using a towed body equipped with multiple frequency acoustical, bio-optical, and physical sensor systems. The primary focus is on making high-resolution measurements of volume backscattering and target strength of plankton and nekton throughout the Georges Bank region, complemented with optical and physical data, to provide a multi-dimensional base of estimates of the spatial distribution of biomass and size frequency of acoustical targets which span the size range of the target species (cod, haddock, Calanus, and Pseudocalanus) and their predators. The multi-frequency, multi-beam system will provide high spatial resolution estimates of volume backscattering and target strength. The bio-optical system will provide high resolution video images of the plankton which will be used to determine the relative composition and size distribution of the taxa along the tracklines in the immediate vicinity of the towed body. These data together with theoretical models will be used to interpret the acoustical data in terms of meaningful biological properties, such as biomass and size distribution. The physical sensors will provide the information about fine to coarse-scale physical structure of the Bank environment and also the micro-structure relevant to predator-prey interactions. The acoustic measurements can be directly related to the data generated by the optical and net collections of plankton and nekton. The acoustical spatial maps and time-series will also provide essential linkage between the physical oceanographic conditions on the Bank and the biological distributions of the species as determined from the net collections at the stations distributed throughout the Georges Bank region.
