Dinoflagellate cyst assemblages in surface sediments of the Laptev Sea region (Arctic Ocean) and their relationship to hydrographic conditions

Abstract

Kunz-Pirrung, M. 2001. Dinoflagellate cyst assemblages in surface sediments of the Laptev Sea region (Arctic Ocean) and their relationship to hydrographic conditions. ABSTRACT: The occurrence and distribution of dinoflagellate cysts in surface sediments from the Laptev Sea shelf and the adjacent continental margin have been studied in relation to surface water conditions. Assemblages were interpreted by visual inspection and Q-mode factor analysis. The inner Laptev shelf is a type-area for polar environments because of the near absence of relatively warm waters from the Pacific or Atlantic oceans and an extensive seasonal sea-ice cover. Assemblages are of low diversity and are dominated by the cold water taxon Islandinium minutum and related morphotypes. The common occurrence of distinctive polykrikoid cyst morphotypes is an indicator of polar environments. Furthermore, a strong supply of fresh water in summer influences the surface water conditions, and is a major factor controlling the occurrence and distribution of dinoflagellate cysts. The dinoflagellate cysts Nematosphaeropsis labyrinthus and Operculodinium centrocarpum are restricted to the continental margin, suggesting a relation to the inflow of relatively warm Atlantic waters along the Eurasian continental margin. An abundance maximum of Brigantedinium spp. at the shelf break is related to the mean position of the marginal ice zone.

Interaction between subsurface ocean waters and calving of the Jakobshavn Isbræ during the late Holocene

“…P. dalei is common in polar and subpolar regions (Dale, 1996;Rochon et al, 1999) and has especially been found connected to spring blooms (Dale, 1977;Harland et al, 2004a). In contrast, Islandinium minutum thrives in areas of extensive seasonal sea-ice cover and/or polar surface water conditions (e.g., Rochon et al, 1999;de Vernal et al, 2001;Head et al, 2001;Kunz-Pirrung, 2001;Hamel et al, 2002;Marret and Zonneveld, 2003;Grøsfjeld et al, 2006) while…”

Hydrological changes in the White Sea during the historical period inferred from analysis of dinocysts

“…In examined open areas of Kandalaksha and Onezhskii bays, its content varies from 70 to 95%, which is determined by minimal (0.2-0.5 mg/l) concentrations of suspended matter in waters and, correspondingly, favorable conditions for photosynthesis [9]. The occurrence of this species in dinocyst assemblages of the Arctic seas [7] is thought to be related to the distribution of warm Atlantic waters [10,13]. In the examined cores, dinocysts of autotrophic species dominate and their integral share ranges from 75 to 95%.…”

“…The analysis of dinocysts, which makes it possible to reconstruct various parameters of water masses washing the Arctic shelf, has become a promising method in paleohydrological studies, widely used in recent years [10,11]. Dinoflagellates, which represent one of the main phytoplankton groups in the Arctic Seas, the White Sea included, form cysts with biopolymer envelopes, which are preserved in sediments.…”

Dinoflagellate cysts in the surface sediments of the White Sea

“…Cysts of Polykrikos sp. Arctic morphotype, first identified in 2001 [31], are characteristic (up to 2%) of Kandalaksha and Dvina bays. Cysts of Bitectatodinium tepikiense, which also refers to widely spread tropical-boreal notal species [9], are encountered in the northern part of the Basin and in Dvina Bay (up to 5-10%).…”

“…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.…”