Distribution of dinoflagellate cycst at ODP Site 123-765 (Table 1)

Site 765 contains a sequence of tropical, middle Miocene to Holocene dinoflagellate cysts. These diverse assemblages are characterized by abundant Polysphaeridium zoharyi and Spiniferites bulloideus. Abundances of Impagidinium spp. and Nematosphaeridium spp. reflect the shelf-to-slope origin of the assemblages. One new genus, Blysmatodinium, and two new species, Nematosphaeridium (?) wrennii sp. nov. and Blysmatodinium argoi, are described.

Occurrence of Selenopemphix undulata sp. nov in late Quaternary sediments of the Pacific Ocean

Detailed palynological studies in the northeast (NE) Pacific, Strait of Georgia (BC, Canada), southeast (SE) Pacific and northwest Pacific (Dongdo Bay, South Korea) resulted in the recognition of the new dinoflagellate cyst species Selenopemphix undulata sp. nov. This species is restricted to cool temperate to sub-polar climate zones, where it is found in highest relative abundances in highly productive non- to reduced upwelling regions with an annual mean sea-surface temperature (aSST) below 16 °C and an annual mean sea-surface salinity (aSSS) between 20 and 35 psu. Those observations are in agreement with the late Quaternary fossil records from Santa Barbara Basin (ODP 893; 34°N) and offshore Chile (ODP 1233; 41°S), where this species thrived during the last glacial. This period was characterised by high nutrient availability and the absence of species favouring upwelling conditions. The indirect dependence of S. undulata sp. nov. abundances on nutrient availability during reduced or non-upwelling periods is expressed by the synchronous fluctuations with diatom abundances, since the distribution and growth rates of the latter are directly related with the availability of macronutrients in the surface waters.

Concentrations of dinoflagellate cysts in the surface layer of bottom sediment from the White Sea

Dinoflagellate cysts were studied in 42 samples from surface sediments of the White Sea. Total concentration of dinocysts varies from single cysts to 25000 cyst/g of dry sediments, which reflects biological productivity in White Sea waters and regional particular features of sedimentation processes. The highest concentrations are observed in silts; they are related to the regions of propagation of highly productive Barents Sea waters in the White Sea. Generally, spatial distribution of dinocyst species in the surface sediments corresponds to distribution of the major types of water masses in the White Sea. Cysts of relatively warm-water species (Operculodinium centrocarpum, Spiniferites sp.) of North Atlantic origin that dominate in the sediments indicate an intensive intrusion of Barents Sea water masses to the White Sea along with hydrological dwelling conditions in the White Sea favorable for development of these species during their vegetation period. The cold-water dinocyst assemblage (Islandinium minutum, Polykrikos sp.) is rather strictly confined to inner parts of shallow-water bays, firstly, those adjacent to the Onega and Severnaya Dvina river mouths.