Spatial Variability of Primary Production and Chlorophyll in the Laptev Sea in August–September

The spatial distribution pattern of phytoplankton primary production (PP) and chlorophyll was studied by the data of three cruises in August–September 2015, 2017, and 2018. The integral primary production (IPP) in water columns along the transect from the Lena River mouth to the continental slope was 2.8 times higher than that along the transect from the Khatanga River mouth, which was explained by the illumination and mineral nutrition. The rise in the chlorophyll content in the layer of photosynthesis (Chl pl ) along the transects across the continental slope was related to the formation of deep-water maxima. The increase in IPP and Chl pl was allocated to the continental slope. The mean IPP < 100 mg C/m 2 per day in August–September is the evidence of oligotrophy of the Laptev Sea late in summer and early in autumn.