Diatoms and silicoflagellates abundances in the sediment core A12-4 from Amur Bay (Japan Sea)

Diatoms and silicoflagellates from sediments in Amur Bay (Japan Sea) were analyzed with high temporal resolution to examine changes over the last 150 years. The age of sediments was estimated from unsupported 210Pb controlled by 137Cs. Siliceous microalgae examined in each cm of two sediment cores demonstrated significant changes in the ecological structure of the assemblages that reflected changes in sedimentation conditions. The obtained data suggest that the environmental changes over the last 150 years in Amur Bay are associated with the weakening of river runoff due to deforestation, sea level rise caused by global warming, and the increase of siliceous microplankton productivity that resulted in the formation of seasonal bottom hypoxia.