Physical and biological influence on the mesoscale zooplankton distribution along an Arctic shelf region

This thesis addresses the influence of mesoscale physical and biological processes on mesozooplankton over a Norwegian subarctic shelf region. A combination of traditional net sampling and high resolution acoustic and optical sensors is used to assess the composition, abundance and distribution of mesozooplankton in relation to the mesoscale physical environment over a roughly 8000 km2 shelf region containing a shallow bank and adjacent trough. Two primary water masses, Norwegian Atlantic Water (NAW) and Norwegian Coastal Water (NCW), interact with the topography to form frontal boundaries, eddies, and intrusions. These physical features are associated with high zooplankton abundance during late spring and late summer and serve as mechanisms of onshelf transport and entrainment for zooplankton. Data pertaining to the copepod Calanus finmarchicus indicate that their seasonal presence in the region may be dependent upon both local populations as well as advection from other regions. The onshelf intrusion of the NAW onto the shelf may be important for the cross-shelf transport of C. finmarchicus between coastal regions and offshore overwintering grounds.