Holocene variations of sea‐surface conditions in the southeastern Barents Sea, reconstructed from dinoflagellate cyst assemblages

Abstract

Palynomorphs were analysed in two sediment cores from the southeastern Barents Sea representing the past 8.3 and 4.4 kyr. High dinocyst contents and species diversity enabled the application of the best analogue method to quantitatively reconstruct sea-surface salinities, temperatures and ice cover using 677 modern reference sites from the North Atlantic and Arctic seas, including new data from the Barents Sea reported here. At the southern core site, where waters are affected by the Atlantic inflow, sea-surface conditions were relatively warm and stable between ca. 8000 and 5000 calendar yr BP. In contrast, the past 5 kyr had periods with cooler temperatures and extended ice cover, fluctuating mostly at 1-1.5 kyr frequencies at both sites. Most pronounced coolings occurred around 8.1, 5, 3.5-3.2 and 2.5 ka. The northern site additionally shows younger cooling events, tentatively dated to 1.4, 0.3 and 0.1 ka. Identified variations in seasurface conditions indicate changes in Atlantic water inputs to the Barents Sea. Our results generally correlate to palaeoclimatic reconstructions from northwestern Eurasia, exemplified by palynological records from Karelia. This correlation suggests that sea-surface variations in the Barents Sea reflect large-scale changes in atmospheric and oceanic interactions between the North Atlantic and the Arctic.

Reconstruction of Atlantic water variability during the Holocene in the western Barents Sea

“…Several studies record a cooling in the late Holocene in both the bottom (Ślubowska-Woldengen et al, 2007;Risebrobakken et al, 2010) and surface water masses (Voronina et al, 2001;Hald et al, 2007;Rasmussen et al, 2007;Risebrobakken et al, 2010), which could be related to declining summer insolation (Berger and Loutre, 1991) or displacements of Arctic and polar water masses (Hald et al, 2007). Opposite to this cooling, two high-resolution studies from Bear Island and the western and northern Svalbard shelf (Jernas et al, 2013) infer a warming over the last ∼ 200 yr induced by the renewed inflow of Atlantic water.…”

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

“…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.…”

Dinoflagellate cysts in the surface sediments of the White Sea

“…(1) The concentrations of dinoflagellate cysts in the sediments of the White Sea are 20 times as low as those calculated previously for the Barents Sea [46] and are compatible with the values obtained for other Arctic seas, for example, for the Laptev Sea [30]. Their quantitative distribution over the White Sea is controlled by the grain-size composition of the sediments, which is responsible for the preservation and conditions of existence of cysts, and by the salinity of the surface waters, which governs the number of planktonic species of dinoflagellates.…”

“…Meanwhile, only one-fifth of them form cysts that can be conserved in the sediments [30,34]. In the recent years, the studies of the dinocysts of the Arctic seas have made great progress and allowed scientists to reveal the general regularities of their composition and distribution in the bottom sediments depending on the hydrological and ice conditions of the shelf [26,30,31,35,40,46]. Up to the present, for this group of microfossils with different degrees of detailing, the characteristics of the species and quantitative compositions of their assemblages in the sediments of almost all of the Arctic seas have been obtained except for in the East Siberian and White seas.…”