DIATOMS OF PROTECTED AREAS OF NORTHEAST ASIA AS INDICATORS IN A GRADIENT OF GEOGRAPHICAL AND CLIMATIC FACTORS

Northeast Asia is a vast region encompassing diverse natural and climatic zones, from arctic tundra to taiga, with much of it located within permafrost. This study of the regional diatom communities helped identify a number of important patterns and assess processes associated with past global climate change, as well as current climate trends and anthropogenic impacts. Protected Areas serve as natural laboratories for studying the response of biota to geographic and climatic conditions. Diatoms have long been recognised by experts as reliable bioindicators of the environment. However, such research in the regional Protected Areas remains insufficient. The main goal of our study was to assess the resilience of diatom communities across a broad gradient of geographical and climatic factors in Northeast Asia, using Protected Areas with the best-studied diatom floras as an example. Our studies were conducted in the Olyokma State Nature Reserve (Russia) as a model area in 2011 and 2024. Using scanning electron microscopy, we have increased the diatom species list of the Olyokma State Nature Reserve by 269 species. At most stations within the Olyokma State Nature Reserve, genera such as Pinnularia, Eunotia, and Gomphonema predominate in terms of the number of taxa; representatives of these three genera clearly play a key role in the studied flora. The intraspecific variability index Subspecies/Species for the water bodies of the Olyokma State Nature Reserve ranged from 1.00 to 1.06. Overall, 66% of diatom species in Olyokma State Nature Reserve are classified in one or more threat categories by IUCN; five diatom species are in the «Critically Endangered» category. Bioindication and statistical methods showed that the waters of the Olyokma State Nature Reserve correspond to natural water properties. Indicator characteristics demonstrate a significant response of diatom species composition to changes in salinity and pH. For a comparative analysis of our results, we selected 11 most well-studied diatom floras in Protected Areas of Northeast Asia using the Willis criteria. Comparative analysis revealed an increase in the number of taxa in coastal areas, which may be related to the ecotone effect occurring at the interface between continental and marine habitats. In Protected Areas without permafrost, with a milder climate and a longer open-water period, increased intraspecific variability and a specific number of species per unit area were observed. Patterns in the spatial distribution of diatoms were identified in 12 Protected Areas. Geography and the associated permafrost-climate interface play a significant role in shaping diatom communities in Protected Areas. The study is important for developing a framework for monitoring biodiversity in Protected Areas and climate change in the region.