HYPOTHESES

(which we feel describe the essential elements that contribute to the high productivity of Georges Bank)

1. The flux of new nutrients into the tidal front in spring and early summer is due primarily to tidally driven upwelling on the north flank and northeast peak.

 

2. A major factor causing interannual variability of the nutrient flux is the changes in deep-water inflow in the Northeast Channel, i.e., nutrient-poorer Labrador Slope Water vs. comparatively nutrient-richer Warm Slope Water from the south.

 

3. The productivity over the crest of Georges Bank, primarily a recycling regime, is maintained by a lateral flux of plankton (particulate and dissolved organic nitrogen) produced in the tidal mixing front.

 

4. The most productive region of Georges Bank can be characterized as a donut-shaped domain situated at the tidal front with nutrient injections greatest along the north flank, a clockwise advected plume of elevated phytoplankton and zooplankton production resulting from these injections, and larval retention along the south flank.