Variations in sea surface conditions and sea level through the Holocene in the Kandalaksha Bay, the White Sea, were reconstructed based on the study of core sediments from the outer Kandalaksha Bay, using the modern analog technique applied to dinocysts in addition to diatoms, TOC, δ¹³C_org, CaCO₃, and grain size data. The chronostratigraphy of the core sediments was defined from accelerator mass spectrometry ¹⁴C dates on mollusk shells. The results indicated an increase in water depth in the outer Kandalaksha Bay and in the central Dvina Bay until the late Holocene. From about 9.5 to 7.5 cal kyr BP, the data suggested a general trend of increasing sea surface temperatures (up to 14 °C), at least in areas with inflow of Atlantic waters. The last 2.5 kyr were characterized by increased freshwater runoff to the White Sea.

This paper demonstrates the results of diatom analysis of the Holocene sediments from the southeastern part of the Tersky Coast of the White Sea. The main subject of the study is the diatom assemblages’ concentration and composition, as well as the ratio of the main diatom ecological groups in sediments. The study sites were located on the Tersky Coast from the village Chavanga to the right coast of the Varzuga River, at heights from 17 to 52 m. Our reconstruction of the Tersky Coast of the White Sea development is based on diatom study of Holocene sediments from three cores. Age was determined according to radiocarbon dating. In this work, the author determines the features of environmental development, starting from the first half of the early Holocene, clarified the age of the main transgressive stages - Folas, Tapes, Trivia and the absolute heights of their marine sediments. According to the changes in concentration and composition  of the main ecological groups of diatoms, the author records the significant trends in the water temperature changes in coastal reservoirs and hydrobiological conditions in the Holocene, such as short-term decrease in the temperatures of the end of Boreal and the first half of Atlantic time, the Holocene hydrobiological optimum, and changes in temperatures of the Subboreal and Subatlantic time.

The overview of the 20-years joint Russian-German multidisciplinary researches in the Arctic are represented in this article. Data were obtained during numerous marine and terrestrial expeditions, all-year-round measurements and observations. On the basis of modern research methods including satellite observation, radiocarbon (AMS ¹⁴C) dating of the Arctic sea sediments, isotope, biochemical and other methods, the new unique records were obtained. Special emphasis devoted to the latest data concerning modern sea-ice, ocean and sedimentation processes, evolution of the permafrost and paleoenvironments in the Laptev Sea System.