Scotian Shelf Crossovers: Zooplankton Distributions
Karen Wishner and Dawn Outram (URI)
As part of studies on
the role of episodic features in the input and detrainment of Calanus from
Georges Bank and in conjunction with Gifford and Sieracki's feeding studies, we
sampled the "Cold Plume" (a Scotian Shelf Crossover) along with other
locations on Georges Bank during two 1997 process cruises.
Vertically-stratified MOCNESS tows of cold
plume zooplankton were taken during EN298 (7 - 19 April ) and EN301 (23 May - 3
June). At this time, the Scotian Shelf
Crossover water (defined as water <32 ppt salinity) had high abundances of
total Calanus, and especially particular Calanus lifestages, when compared with
other northeast peak and Georges Bank samples.
This suggests that the crossovers transport assemblages of Calanus (and
presumably other zooplankton) that differ in developmental phase (and possibly
species composition) from the zooplankton already on the Bank. The importance
of this phenomenon to Bank processes would depend on when and to what extent
this water and its zooplankton assemblage mixes onto the Bank, potentially
seeding the Bank with new populations.
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