Spatial variability of phytoplankton, nutrients and new production estimates in the waters around Svalbard Georgina Owrid, Giorgio Socal, Giuseppe Civitarese, Anna Luchetta, Jozef Wiktor, Eva-Maria Nothig, Inger Andreassen, Ursula Schauer zyxw & Volker Strass Phytoplankton dynamics and carbon input into Arctic and sub-Arctic ecosystems were investigated around Svalbard, in summer 1991. Phytoplankton biomass, species composition and dissolved nutrient concentrations were analysed from water samples collected along seven transects. Phytoplankton biomass was low especially to the north (Chlorophyll-a mean 0.3 pg 1- '), where flagellates dominated the communities and only ice-diatoms were present. To the west, the phytoplankton composition was representative of a summer Atlantic community, in a post-bloom state. Zooplankton grazing, mainly by copepods, appeared to be the main control on biomass to the west and north of Svalbard. In the Barents Sea (east of Svalbard), an ice edge bloom was observed (Chlorophyll-a max. 6.8 pgl-') and the ice edge receded at a rate of approximately zyxwvut 1 1 zyxwv km day-'. The phytoplankton community was represented by marginal ice species, especially Phaeocystis poucherii and Chaeroceros socialis. South of the ice edge, Deep Chlorophyll Maxima (DCM) were observed, as surface waters became progressively nutrient-depleted. In these surface waters, the phytoplankton were predominantly auto- and heterotrophic flagellates. Carbon production measurements revealed high net production (new and regenerated) to the north of the Barents Sea Polar Front (BSPF); it was especially high at the receding ice edge (reaching 1.44gC m-'day-'). To the south, a low level of production was maintained, mainly through regenerative processes. zyxw G. Owrid, School of Oceaii and Eayth Sciences, University of Southampton, European Way, SO14 3ZH Southampton, UK: G. Socal, Iiistitute of Marine Biology C.N.R., Castello 1364/A, 30122 Venice. Italy: G. Civitarese & A. Luchetta, Thalassographrc Institute of Trieste. C.N.R., 34123 Trieste, Italy; J. Wiktor, Arctic Ecology Group, Institute of Oceanology, 81-712. PAN Sopot, Poland; E.-M. Nothig, U. Schauer & V. Strass, Alfred Wegerier Institute for Polar und Marine Resenrch, 0-2850 Bremerhaven, Germany; I. Andreussen, Noiwegian College of Fishen Science, University of Trornsh Tronisg N-9037, Norway. Spatial heterogeneity of phytoplankton commu- nities has been well documented for the temperate latitudes (e.g. Venrick 1988, 1990: Weeks et al. 1995). In contrast, little is known of the disti-ibu- tion, abundance and variability of plankton in ice- covered seas, mainly due to the inaccessibility of these waters throughout a major part of the year. Some progress has been made in the last few years in these polar regions, with the improvement in the capabilities of ice-breakers that enable the collec- tion of information at the marginal ice zone and in the water column under the pack ice (Rey & Loeng Owrid et al. 2000: Polar Research 19(2). 155-171 155