TEMPORAL AND REGIONAL VARIATION IN THE COPEPOD COMMUNITY IN THE CENTRAL BARENTS SEA DURING SPRING AND EARLY SUMMER 1988 AND 1989

In this study, we examined a 3000 km(2) area to the southeast of Bear Island in the central Barents Sea with respect to copepod abundance and depth distribution at nine stations in March, April and May of 1988 and 1989. In order to describe the population dynamics of the most prominent species in the area during the period of study, the annual ascent and abundance of Calanus finmarchicus, Metridia longa and Calanus glacialis are shown. Stage abundance, vertical distribution and cohort development did vary between species and years at one site. The number of species and the complexity of the data for the entire area studied have encouraged us to search for more significant and persistent patterns by using a canonical correlation analysis (CCA). We included a total of 27 species and stage categories, latitude, salinity and sigma from the nine stations in 1989. We performed this analysis for 1989, since we only have environmental data (CTD) available from the same stations in that year. The species-environment relationship showed that the zooplankton community could not be grouped according to area (latitude) or environmental (sigma, salinity) conditions during March-May in 1989. This means that the differences in environmental conditions in the area of study in 1989 do not mediate any consistent gradient in the zooplankton community. When comparing the copepod data for both years, the largest differences are associated with the depth and month vectors. The largest interannual Variation is seen in the copepod community in the depth strata from 100 to 400 m, and is related to a lesser degree of similarity among the species and stages found in this depth interval throughout the study. Two species were particularly responsible for the interannual differences: Pseudocalanus acuspes CV and females, and C.glacialis CV and adults. Changes in these two species are clearly related to major shifts in the hydrographic conditions between the 2 years, where 1988 was generally colder compared to 1989.