Distribution, Export and Alteration of Fossilizable Plankton in the Nordic Seas

Abstract

The present study gives an overview of recent research results concerning the distribution of living fossilizable plankton groups (coccolithophores, diatoms, dinoflagellate cysts, radiolarians and planktic foraminifers) in the water column ofthe Nordic Seas. Infonnation is combined with results of sediment trap investigations on fluxes and the species composition of these fossilizable plankton groups in the Nordic Seas and their relation to oceanographic conditions. In order to validate spatial and temporal occurrence patterns of the plankton assemblages, their fluxes were monitored with sediment traps over several years in three different oceanic regions, characterized by the major surface water masses of the Nordic Seas. In addition, the alteration processes on settling plankton assemblages were investigated at three water depths. Oceanographic domains in the Nordic Seas can be clearly distinguished on the basis of the export of different plankton assemblages. The Norwegian Sea is dominated by calcareous plankton and the Greenland Sea and the Jan Mayen Current are dominated by siliceous plankton organisms. All fossilizable plankton groups show a corresponding decrease with low interannual variations in the number of species from the temperate Norwegian Sea to the colder Jan Mayen Current and the Greenland Sea. Dissolution is one of the major alteration processes and alters diatom assemblages significantly during sinking and settling. No quantitative signal of siliceous plankton groups is preserved in the deep traps or in sediments. The second major alteration process is lateral advection. This process influences the investigated sites on different scales.

Calcium isotopic composition of high-latitude proxy carrier <i>Neogloboquadrina pachyderma</i> (sin.)

“…The corresponding temperature and salinity data for the months of July to September, which characterise the main planktonic bloom in this region (Kohfeld et al, 1996;Schröder-Ritzrau et al, 2001), were extracted from the hydrographic database "World Data Atlas 2001" (Conkright et al, 2002) using the software "Ocean Data View" (Schlitzer, 2007).…”

Global prediction of planktic foraminiferal fluxes from hydrographic and productivity data

“…We extended the database ofŽarić et al (2005) by adding several North Atlantic traps (Jensen, 1998;Peinert et al, 2000;Schröder-Ritzrau et al, 2000;Antia et al, 2001;Schiebel, 2002) complementing SST and PEX data for every sample as described byŽarić et al (2005). Furthermore we added information on the depths of the mixed layer.…”

The coccolithophores Emiliania huxleyi and Coccolithus pelagicus: Extant populations from the Norwegian–Iceland Seas and Fram Strait

“…C. pelagicus has previously been associated with mesostrophic to eutrophic waters in phytoplankton-rich frontal systems of the Nordic Seas (Andruleit, 1997;Samtleben et al, 1995a), suggesting an ecology controlled by factors other than temperatures e.g. nutrients and irradiance (Baumann et al, 2000;Schröder-Ritzrau et al, 2001;Balestra et al, 2004;Giraudeau et al, 2004). In addition, some studies have suggested turbulence as an important factor preventing the sinking of this heavily calcified species from the photic zone (Cachão and Moita, 2000) hence favoring its production in the highly mixed upper Arctic Water (ArW) mass.…”

“…Coccolithophore production is usually delayed by the diatom spring blooms until silica is depleted (Samtleben and Schröder, 1992;Baumann et al, 2000), and it is generally confined to surface waters above or close to the thermocline (Schröder-Ritzrau et al, 2001). In the southeastern Norwegian Sea, the coccolithophore production may be enhanced as early as May, with a progressive transition towards the Greenland Sea peaking in late summer/fall (Samtleben and Bickert, 1990;Samtleben et al, 1995a;Baumann et al, 2000;Schröder-Ritzrau et al, 2001). Hence the living coccolithophore community shows a broad summer/fall maximum in the Nordic Seas (Schröder-Ritzrau et al, 2001), with consistently higher cell numbers of living coccolithophores during this high production period than during the winter-spring low production period (Baumann et al, 2000).…”