Seasonal patterns in zooplankton community structure on the Newfoundland and Labrador Shelf

We report on the patterns in zooplankton community structure on the Newfoundland and Labrador Shelf from seasonal collections along oceanographic sections during 2000–2007. We use a combination of constrained and unconstrained multivariate methods to assess latitudinal and cross shelf patterns in community structure. Both physical and biological features of the region are dominated by the cross-shelf gradient in water mass characteristics although there is evidence of a latitudinal gradient that may be a reflection of the influence of freshwater outflow from the Arctic. All analyses reveal a strong and consistent pattern in species composition among water masses that extends across spring, summer and autumn, although there are some variations that occur among seasons that reflect differences in development state of certain taxa. The strong association between community structure and water mass characteristics in the region may be the result of the Newfoundland and Labrador Shelf being at the intersection of several major oceanographic domains, bounded by strong Labrador and Gulf Stream currents, that allows the formation and persistence of well defined zooplankton communities. Our findings have implications for the region’s potential as a monitoring location for long term changes in ocean state.

Research highlights
► The cross-shelf gradient in zooplankton community reflects the physical features of the region.
► A latitudinal gradient was most strongly apparent during the summer surveys.
► The species that contributed most to the separation of communities are widespread.
► The Newfoundland shelf and slope may represent a highly spatially structured ecosystem.
► This system allows the formation and persistence of well defined zooplankton communities.