Effect of the Outflow from the Gulf of St. Lawrence on Nova Scotia Shelf Zooplankton

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Sameoto, D. D., Herman, A. W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1992
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Calanus glacialis; Copepods
• Online Access: http://dx.doi.org/10.1139/f92-096; http://www.nrcresearchpress.com/doi/pdf/10.1139/f92-096

Significant differences in concentrations (per square metre) of the copepods Calanus glacialis and C. hyperboreus found between the northeastern (NE) and southwestern (SW) halves of the Scotian Shelf were apparently related to the Gulf of St. Lawrence outflow. This outflow introduces these species to the Shelf during late winter and early spring and is probably responsible for maintaining their populations on the Shelf. Deep basins on the NE half of the Shelf are also sources of breeding animals of these two species. The influence of the Gulf outflow on C. finmarchicus was less clear because a large population of this species was found in the basins and beyond the Shelf break. Temora was the only other copepod genus to show a relationship with the Gulf outflow, indicating that it is carried onto the Shelf from the Gulf. The outflow dominated the surface water of the NE Shelf over the entire year; its influence was less marked on the SW Shelf due to mixing with slope water. This mixing in turn dilutes the concentrations of the Gulf Calanus spp. introduced by the Nova Scotia Current. The Gulf outflow is responsible for the high zooplankton biomass concentrations on the NE Shelf in June and October.