Dinoflagellate cysts as proxies for palaeoceanographic conditions in Arctic fjords

Abstract

AbstractThe potential of using dinoflagellate cysts as proxies for palaeoceanographic conditions and as monitors of the dynamic marine environment of climatically sensitive Arctic fjords was investigated with sediment traps. Dinoflagellate cysts were analysed from three separate deployments in two high Arctic fjords in the Svalbard archipelago. Two deployments in Kongsfjorden on the west coast of Svalbard occurred during 2002 and 2006–2007 and a deployment in Rijpfjorden on the NE coast occurred during 2006–2007. The cyst production displayed peaks of abundance in the spring and late summer with distinct differences in cyst occurrence in different fjords and in different years. The recorded and identified cyst species were consistent both with the hydrography of the fjords and with changes in cyst composition that are comparable to the seasonal shifts in water mass characteristics. The presence of the heterotrophic species Protoperidinium conicum in Kongsfjorden during 2002 is of note and may reflect the availability of a particular food source possibly associated with the strong influx of Atlantic Water. Cysts recovered from Kongsfjorden during 2006–2007 were dominated by Islandinium minutum, an indicator of cold, polar to subpolar conditions. The temperature and salinity characteristics of the ambient hydrography in this period indicated less influence by Atlantic Water than in 2002, and the cyst production was consistent with regional cyst distribution patterns. In Rijpfjorden, cyst assemblages were dominated by Pentapharsodinium dalei, consistent with the fjord being dominated by full Arctic conditions during the mooring deployment and the possible occurrence of stratified water with high productivity during the spring phytoplankton bloom.