Multidimensional zooplankton observations on the northern West Spitsbergen Shelf

Climate change in the Arctic influences the ocean circulation and the hydrographic regime which leads to substantial reconstruction of the zooplankton community, notably a northward shift of dominant boreal species. These unstable Arctic environmental conditions are expected to affect the pelagic food web, which is highly dependent on the consumption of Calanus copepods. The present study is based on multidisciplinary zooplankton observations carried out with net sampling, a Laser Optical Plankton Counter and high frequency echosounding during two summer seasons on the West Spitsbergen Shelf. The extent of northward advection of surface Atlantic origin waters was greater in 2009 than in 2010. Our study determined the position of the surface frontal system and confirmed hydrographical separation of distinctive waters together with their associated fauna. Very abundant assemblages of C finmarchicus dominated Atlantic origin waters in both years while a higher share of C. glacialis was observed in Arctic origin waters during colder 2010. The observed zooplankton assemblages ranged in size up to a few kilometres horizontally and >40 m vertically. Combined implementation of conventional sampling, acoustic and optical methods provided a full spatial zooplankton distribution picture in an area of great importance as a potential feeding ground for planktivores. (C) 2012 Elsevier B.V. All rights reserved.