Response of the Lake Ecosystem of the Lesser Kuril Ridge to Paleoclimatic and Seismic Events

In this paper we restore moisture changes since the Younger Dryas based on the study of diatom flora in sediments of the Zelenyi coastal paleolake, the Lesser Kuril Ridge. The section includes numerous interlayers of tephra, the sources of which were located on the islands of Kunashir and Hokkaido, and interlayers of tsunamigenic sands, which made it possible to determine the impact of catastrophic events on changes in the ecological situation. The stages of the development of the lake are identified and its evolution is analyzed during short-period climatic rhythms. The reservoir had its maximal depth at the beginning of the Holocene, and planktonic forms predominated among diatoms. Three phases when the lake turned into a lagoon were established, and the erosion of the barrier form most likely caused this during large tsunamis associated with earthquakes. Except for these cases, the main factor leading to the change in lacustrine–marsh environments was climate change. We identified relatively dry periods and wet periods associated with an increase in the intensity of cyclogenesis in the South Kurils region. We correlated with high-resolution paleoclimatic records from archives for the Southern Kuriles; the most striking events were compared with data for Sakhalin and the continent. Changes in moisture on the islands and the margin of the mainland in the Middle–Late Holocene were established to be in antiphase in most cases, except for the cooling of 2800–2500 BP and the Little Ice Age. The connection of regional climatic changes with anomalies in the ocean and atmosphere of the Asia-Pacific region is shown.