Diatoms and aquatic palynomorphs in the Barents sea sediments: main distribution patterns and use in palaeoceanological studies

The Chapter deals with the uniqueness of the Barents Sea and adjacent sea areas from the viewpoint of the main groups of phytoplankton (diatom algae and dinoflagellate) development and their reflection in tanatocenoses of bottom sediments. Special attention is paid to the distribution of microfossils in surface waters as an indicator of the modern sea ice and hydrological signal. A distinctive feature of the Barents Sea tanatocenoses is the frequency of re-deposited Paleogene and Cretaceous forms of diatoms and dinocysts. Despite all the difficulties in finding microfossils in bottom sediments, data were obtained on characteristic associations mainly related to the redistribution of relatively warm North Atlantic waters. The issues of microfossils in cores and boreholes located on the Barents Sea shelf and continental slope are considered and the most extensive material on changes in sedimentation conditions in the Pleistocene and Holocene is generalized.

Diatoms in Volcanic Soils of Mutnovsky and Gorely Volcanoes (Kamchatka Peninsula, Russia)

Volcanic activity has a great impact on terrestrial ecosystems, including soil algae in general and diatoms in particular. To understand the influence of volcanoes on the biodiversity of diatoms, it is necessary to explore the flora of these microorganisms in regions with high volcanic activity, which includes the Kamchatka peninsula. During the study on diatoms in the soils of Mutnovsky and Gorely volcanoes of Kamchatka, 38 taxa were found. The Mutnovsky volcano diatom flora was more diverse and accounted for 35 taxa. Eunotia curtagrunowii, Humidophila contenta, and Pinnularia borealis were the dominant species. In the Gorely volcano, only 9 species were identified, with Caloneis bacillum and Pinnularia borealis prevailing in the samples. Overall, the genera Pinnularia and Eunotia were the most diverse in the studied area. The diatom flora of the studied volcanoes comprises mostly cosmopolitan small-sized taxa with a wide range of ecological plasticity. Our data confirm the high adaptive potential of diatom algae and add new knowledge about the ecology and biogeography of this group of microorganisms.

About a new representative of the genus Aulacoseira Thw. (Bacillariophyta) for the flora of Ukraine

In this study, scanning electron microscopy images of valves of the centric diatom algae Aulacoseira subborealis (Nygaard) Denys, Muylaert et Krammer from from the Kaniv Reservoir and the Desna River are analyzed. The quantitative (colony size, valve diameter and mantle height, the ratio of mantle height to valve diameter, number of areola rows and areolae in 10 µm on the mantle, ring-shaped diaphragm size) and qualitative (short pointed spines, areolae arrangement on the valve face and the mantle) morphological characteristics correspond to the diagnosis of A. pusilla (F.Meister) A.Tuji & A.Houki, a new species for the flora of Ukraine. In the analyzed material, minimum values of the mantle height and the height/diameter ratio are lower than in the published data.

MICROFOSSILS AS EVIDENCE OF TRASFORMATION OF GEOSYSTEMS DURING MEDIEVAL DEVELOPMENT OF SOUTH PRIMORYE (FORTRESS STEKLYANUKHA-2)

Представлены результаты изучения спорово-пыльцевых спектров и диатомовых водорослей в разрезах отложений в пределах средневвекового городища Стеклянуха 2. Восстановлена палеоландшафтная ситуация и выделены признаки антропогенного воздействия на растительность. Палиноспектры из поверхностной почвы отражают активное сельскохозяйственное освоение близлежащих речных долин со второй половины XIXвека. Изучение диатомовых водорослей в древнем котловане подтвердило предположение, что его использовали для хранения запасов воды. The results of pollen spectra and diatoms study within the middle-century settlement of Steklyanukha 2 are presented. The paleolandscape situation was restored and signs of anthropogenic impact on vegetation were identified. Pollen from surface soil reflect the active agricultural development of nearby river valleys from the second half of the 19th century. A study of diatom algae in an ancient pit confirmed the assumption that it was used to store water reserves.

Morphology, taxonomy and distribution of the rare species Aulacoseira cataractarum (Hustedt) Simonsen (Bacillariophyta) in Russia

This scanning electron microscopy study was undertaken to reanalyze frustule samples of the centric diatom algae Aulacoseira cataractarum, collected earlier from a swamp in the Uzon volcanic caldera (Kamchatka). This species, under the name of Melosira cataractarum, was reported before from a number of waterbodies in Russia. Later it was transferred to the genus Aulacoseira Thwaites – A. cataractarum (Hustedt) Simonsen (Simonsen, 1979), and then – to the genus Pseudostaurosira (A.Grunow) D.M.Williams & F.E.Round, under the name of P. seudostaurosira cataractarum (Hustedt) Wetzel, Morales et Ector. In this study we specify perforation of intercalary bands, the shape of the valves and spines as well as the number of valve face and mantle areolae per stria and their shape. Based on the original and published data an extended diagnosis of P. cataractarum is presented. Scanning electron microscope images of frustules of the centric diatom algae.