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 km² area to the southeastof Bear Island in the central Barents Sea with respect to copepodabundance and depth distribution at nine stations in March,April and May of 1988 and 1989. In order to describe the populationdynamics of the most prominent species in the area during theperiod of study, the annual ascent and abundance of Calanusfinmarchicus, Metridia longa and Calanus glacialis are shown.Stage abundance, vertical distribution and cohort developmentdid vary between species and years at one site. The number ofspecies and the complexity of the data for the entire area studiedhave encouraged us to search for more significant and persistentpatterns by using a canonical correlation analysis (CCA). Weincluded a total of 27 species and stage categories, latitude,salinity and sigma from the nine stations in 1989 We performedthis analysis for 1989. since we only have environmental data(CTD) available from the same stations in that year The species-environmentrelationship showed that the zooplankton community could notbe grouped according to area (latitude) or environmental (sigma,salinity) conditions during March–May in 1989. This meansthat the differences in environmental conditions in the areaof study in 1989 do not mediate any consistent gradient in thezooplankton community. When comparing the copepod data for bothyears. the largest differences are associated with the depthand month vectors. The largest interannual variation is seenin the copepod community in the depth strata from 100 to 400m. and is related to a lesser degree of similarity among thespecies and stages found in this depth interval throughout thestudy. Two species were particularly responsible for the interannualdifferences: Pseudocalanus acuspes CV and females, and C glacialisCV and adults. Changes in these two species are clearly relatedto major shifts in the hydrographic conditions between the 2years, where 1988 was generally colder compared to 1989.