The Northeast Water Polynya during summer 1992: Distribution and aspects of secondary production of copepods

Abstract

Zooplankton ecology in the Northeast Water Polynya was investigated from July 15 to August 15, 1992. The initial hypotheses were that the polynya would be a site of enhanced secondary production and that the copepod community would be composed of varying proportions of North Atlantic and Arctic species advected onto the Greenland shelf through the Northern and Southern Troughs. Striking contrasts were observed between the northern and southern regions of the shelf. The southern region was dominated numerically by the North Atlantic species Calanus finmarchicus, while species of Arctic origin (C. glacialis, C. hyperboreus, Metridia longa) dominated in the northern region. The polynya itself contained few of the herbivorous Calanus species but, instead, was dominated by the omnivore M. longa. Secondary production of C. glacialis, represented by egg production rates, was high in all regions (55–88 eggs/female/day). However, because of low abundances of the large bodied Calanus species within the polynya, it is estimated that the herbivorous copepods were not significant consumers of primary production in the polynya. Fundamentally different pathways for the cycling of carbon may exist in the northern and southern regions. Copepod communities may utilize much of the primary production in the south but only a small proportion of the primary production in the polynya, where significant proportions may be unconsumed.