Dinoflagellate cyst assemblages as tracers of sea‐surface conditions in the northern North Atlantic, Arctic and sub‐Arctic seas: the new ‘n = 677’ data base and its application for quantitative palaeoceanographic reconstruction

Abstract

L. and Voronina, E. 2001. Dinoflagellate cyst assemblages as tracers of sea-surface conditions in the northern North Atlantic, Arctic and sub-Arctic seas: the new 'n = 677' data base and its application for quantitative palaeoceanographic reconstruction.ABSTRACT: The distribution of dinoflagellate cyst (dinocyst) assemblages in surface sediment samples from 677 sites of the northern North Atlantic, Arctic and sub-Arctic seas is discussed with emphasis on the relationships with sea-surface parameters, including sea-ice cover, salinity and temperature of the coldest and warmest months. Difficulties in developing a circum-Arctic data base include the morphological variation within taxa (e.g. Operculodinium centrocarpum, Islandinium? cezare and Polykrikos sp.), which probably relate to phenotypic adaptations to cold and/or low salinity environments. Sparse hydrographical data, together with large interannual variations of temperature and salinity in surface waters of Arctic seas constitute additional limitations. Nevertheless, the use of the best-analogue technique with this new dinocyst data base including 677 samples permits quantitative reconstruction of sea-surface conditions at the scale of the northern North Atlantic and the Arctic domain. The error of prediction calculated from modern assemblages is ±1.3°C and ±1.8°C for the temperature of February and August, respectively, ±1.8 for the salinity, and ±1.5 months yr −1 for the sea-ice cover. Application to late Quaternary sequences from the western and eastern subpolar North Atlantic (Labrador Sea and Barents Sea) provide reconstructions compatible with those obtained using the previous dinocyst data base (n = 371), which mainly included modern data from the northern North Atlantic.

Strengths and Weaknesses of Quantitative Climate Reconstructions Based on Late-Quaternary Biological Proxies

“…See also Magny et al (2001Magny et al ( , 2003 for reconstructions of seven climate variables from one data-set. de Vernal et al (2001; use the same dinoflagellate cyst assemblages to reconstruct summer and winter seasurface temperatures, the number of months of ice cover, and summer sea-surface salinity (see Telford 2006 for a critique). The choice of climate variable to be reconstructed is usually done in one of two ways.…”

Holocene Vegetation and Climate History of the Cheshskaya Bay Region, SE Barents Sea, Inferred from the First Pollen Archives

“…No direct indicators of the penetration of North Atlantic Drift (Atlantic-derived waters or ADW) to the Cheshskaya Bay were observed among aquatic palynomorph assemblage of PZ-Ya-I. This primarily concerns the autotrophic species Operculodinium centrocarpum and Pentapharsodinium dalei, which are regarded to indicate ADW influence in the Arctic Basin (KunzPirrung 1998;de Vernal et al 2001). Complete absence of pollen of temperate deciduous plants, such as Ulmus, Corylus, Carpinus, gives additional evidence for initial isolation of the Cheshskaya Bay.…”

Response of marine palynomorphs to Neogene climate cooling in the Iceland Sea (ODP Hole 907A)

“…Impagidinium pallidum has been frequently considered an indicator for cold surface water conditions and a variable range of sea ice cover (e.g. Rochon et al, 1999;de Vernal et al, 2001; al., in press), and its common occurrence (~10%) has been associated with summer SSTs b 15°C . Since H. tectata requires summer SSTs > 9°C and abundances of N. labyrinthus > 50% preponderantly correlate to SSTs b 15°C Zonneveld et al, in press), SSTs might have been in the range of >9 to b15°C.…”

“…nutrient availability, sea ice cover) or within the deeper waters such as selective degradation and dissolution . Species recorded just below this interval (N. labyrinthus, I. pallidum, and S. elongatus) survive harsh conditions with up to 12 months per year sea ice cover (de Vernal et al, 2001;Zonneveld et al, in press) excluding sea ice as a single cause, and nutrient availability might be excluded since diatoms have been constantly recorded in this interval (Stabell and Koç, 1996). Recent studies demonstrate a species-dependent selective aerobic degradation (Zonneveld et al, 2008, and "Impagidinium and Nematosphaeropsis are clearly more resistant than TOC" (Versteegh et al, 2010, p. 177), but all other dinocyst species degrade considerably faster.…”