Copepods in Fram Strait in summer: Distribution, feeding and metabolism

Abstract

A summer study of zooplankton in the Fram Strait area of the Greenland Sea showed elevated abundances of herbivorous copepods in the marginal ice zone or ice-edge compared with copepod communities under the pack ice cover. Several physical factors contributed to this, including the large-scale current systems which deliver both North Atlantic and Arctic plankton to the ice-edge and the effect of melting ice and eddies in increasing primary productivity and standing stocks of phytoplankton. The potential importance of the ice-edge in secondary production was observed directly as increased numbers of juvenile copepods. Indirectly, it can be inferred from observations that copepods under ice-cover were ingesting only enough to meet daily metabolic demands, were metabolizing protein, and were not storing lipid. Copepods were not undertaking diel vertical migration. Abundances of female copepods at the ice-edge were largely a function of currents, while growth of juveniles was dependent on food supply which even at the ice-edge fell short of the calculated requirements of the dominant copepods.

Plankton patchiness in the Polar Front region of the West Spitsbergen Shelf

“…The high-resolution sections in the present study did not extend deep enough to detect the structure of the eddy; however, the analysis of fulldepth hydrographic point measurements, carried out in parallel to the continuous survey, confirmed the oc currence of a mesoscale anticyclonic baroclinic eddy, extending down to approximately 700 m (WSC slope section). Eddies can extend to depths greater than 500 m (Smith 1988), but the most pronounced contrasts in temperature are mostly found in the upper 25−50 m, as in cyclonic eddies in the Fram Strait (Johannessen et al 1987). The eddy observed in the present survey reached a diameter of approximately 30 km, which is a typical size for mesoscale eddies in the Fram Strait (Walczowski 2013), where the Rossby radius of deformation is on the order of 10 km.…”

Nutrient regimes in the marginal ice zone of the Greenland Sea in summer

“…These populations did not undergo vertical migration (Smith 1988). In summer 1984 elevated concentrations of pheophyhn a and a high percentage of microflagellates w e r e observed in t h e ice e d g e zone i n Fram Strait (Smith e t al.…”

Arctic zooplankton do not perform diel vertical migration (DVM) during periods of midnight sun

“…The influence of sea ice cover on zooplankton is complex, species specific, and differs among regions and seasonals. Smith (1988) concluded that in summer in Fram Strait, the ice edge had a positive effect on herbivorous zooplankton abundances because of elevated concentrations of plant biomass. However, Hirche et al (1991) did not find any enhanced biological activities along the ice edge in Fram Strait during the same season, although he mentioned considerable regional variability related to physical mesoscale processes.…”