Summer macrozooplankton assemblages of Arctic shelf: A latitudinal study

The distribution, abundance, biomass, and community structure of macrozooplankton were investigated in relation to oceanographic conditions in the Barents Sea during summer 2013, using an IKS-80 net (0.5 m(2) mouth opening, 550 mu m mesh). Overall, we found 20 taxa (11 in Murmansk Coastal Water-MCW and in Atlantic Water-AW, 13 in Arctic Water-ArW, and 19 in Barents Sea Water-BSW). Total macrozooplankton abundance varied between 36 and 1116 ind. m(-2) (0.2-4.6 ind. m(-3)) with a mean value of 238 +/- 34 ind. m(-2) (1.0 +/- 0.1 ind. m(-3)) for the entire area. Although the catch was fairly diverse, a small number of species accounted for the majority of the total abundance and biomass. The most abundant taxa were Parasagitta elegans (MCW, AW, BSW, ArW), Thysanoessa spp. larvae (MCW, AW), Mertensia ovum (BSW), Aeginopsis laurentii (BSW), Dimophyes arctica (ArW), and Themisto libellula (ArW). Total macrozooplankton biomass ranged from 17 mg dry mass (DM) m(-2) (0.1 mgDM m(-3)) to 6710 mgDM m(-2) (23.1 mgDM m(-3)), averaging 1058 +/- 240 mgDM m(-2) (4.3 +/- 0.9 mgDM m(-3)) across the study area, with Parasagitta elegans dominant by biomass. Cluster analysis revealed three communities (southern, central and northern) which demonstrated clear variations with latitude. Canonical correspondence analysis showed that location (latitude) and environmental conditions (mean temperature, salinity, mean phytoplankton abundance and biomass) explained 36% of the spatial variability in macrozooplankton communities. In BSW, there was a strong positive correlation between total macrozooplankton biomass and mesozooplankton stock suggesting an important role for food availability in controlling macrozooplankton variability. Predator-prey interactions also might play an important role in influencing the spatial distribution of macrozooplankton. The results may be useful as basis for future investigations of macrozooplankton in order to detect possible influence of changing environment on plankton communities of the Barents Sea during modern warming trend in the Arctic.