Charles H. Greene, Mark C. Benfield, Peter H. Wiebe
Calanus finmarchius dominates zooplankton secondary production on Georges Bank during spring. The Georges Bank Calanus population is derived from diapausing populations in the deep basins of the Gulf of Maine and slope waters adjacent to the Bank. It is hypothesized that processes which regulate the survivorship and supply of Calanus from diapausing populations in the deep basins of the Gulf of Maine determine this copepod species' annual production on Georges Bank. To test this hypothesis, research will be conducted 1) to determine what processes regulate the abundance and survivorship of the diapausing Calanus populations in these deep basins, and 2) to determine how physical and biological processes interact to seed Georges Bank with recruits from these basins each year.
Acoustic and video remote-sensing methods will be used to survey diapausing populations of Calanus in Wilkinson and Georges Basins. Broad-scale surveys conducted in October and December will be used to estimate survivorship of the diapausing Calanus and the scale-dependent spatial coupling of Calanus and its principal invertebrate predators, the euphausiid, Meganyctiphanes norvegica, and the siphonophore, Nanomia cara. Field studies will be conducted during cruises in 1997, 1998, and 1999 and combined with results from feeding experiments to estimate predator-inflicted mortality rates. These latter efforts will focus on quantifying the relative contribution of predation to the overall mortality of the diapausing Calanus population.
Results from the field studies also will be used as input to coupled physical-biological models to examine how physical transport processes in the Gulf of Maine interact with Calanus' seasonal and diel vertical migration behaviors to seed Georges Bank with new recruits during winter. This work will be conducted in collaboration with the modeling group at Dartmouth College.
Other SI: Tim K. Stanton