Diatom surface sediment assemblages around Iceland and their relationshipsto oceanic environmental variables

Canonical correspondence analysis of diatoms from surface sediment samples and oceanographic environmental variables shows that summer and winter sea- surface temperatures, water depth and winter sea-surface salinity are the m ain environmental factors affecting diatom distribution around Iceland. Of these, summer sea-surface temperature is the most important. Five diatom as semblages are distinguished and the distribution of these assemblages is cl early correlated with oceanic current patterns in the region. The sea-ice d iatom assemblage is limited to the area where the East Greenland Current (P olar Water) has its strongest influence, and the cold diatom assemblage is basically controlled by the less cold East Icelandic Current (Modified Pola r Water). The mixing diatom assemblage results from the interaction between the cold East Greenland and East Icelandic Currents and the warm Irminger Current. The warm diatom assemblage is located in the area dominated by the Irminger Current and may be used as an indicator of warm-water masses (Atl antic Water). The coastal diatom assemblage is the only one strongly influe nced by both water depth and summer water temperatures. (C) 2001 Elsevier S cience B.V. All rights reserved.