The sedimentary record of organic-walled dinoflagellate cysts as indicators of palaeoceanographic changes across the Chukchi Borderland and southern Mendeleev Ridge in the western Arctic Ocean

Abstract

Palynological analysis of box- and multi-core sediment samples from the Chukchi Borderland and southern Mendeleev Ridge in the western Arctic Ocean were performed in order to document the distribution of dinoflagellate cyst assemblages and their relationship to palaeoceanographic conditions. A total of 9 genera and 23 dinoflagellate cysts were identified, mainly consisting of O. centrocarpum, Brigantedinium spp. and Spiniferites elongatus. The surface distribution of dinoflagellate cysts shows a sharp decrease from the inner (St. 01A) to the outer shelf areas. The vertical variations of dinoflagellate cyst concentrations in a multi-core sample from site 01A show a gradual increase from the bottom to the top of the core. In the lower part of the core, lower values of total organic carbon and nitrogen contents correspond to lower concentrations of dinoflagellate cysts. Emphasis has been placed on a prominent increase in dinoflagellate cyst concentrations accompanied by total organic carbon and nitrogen contents in the upper part of the core, probably suggesting increased nutrient inputs and marine productivity in the study area.and their relationship to palaeoceanographic conditions. A total of 9 genera and 23 dinoflagellate cysts were identified, mainly consisting of O. centrocarpum, Brigantedinium spp. and Spiniferites elongatus. The surface distribution of dinoflagellate cysts shows a sharp decrease from the inner (St. 01A) to the outer shelf areas. The vertical variations of dinoflagellate cyst concentrations in a multi-core sample from site 01A show a gradual increase from the bottom to the top of the core. In the lower part of the core, lower values of total organic carbon and nitrogen contents correspond to lower concentrations of dinoflagellate cysts. Emphasis has been placed on a prominent increase in dinoflagellate cyst concentrations accompanied by total organic carbon and nitrogen contents in the upper part of the co