The distribution of primary production (PP), chlorophyll a concentration (Chl a ), and size structure of the phytoplankton community were studied in the Kara Sea during the first-year ice retreat in late June 2021. The maximum value of water column PP (IPP) reached 1352 mgC m –2 day –1 . The ice-edge phytoplankton bloom was characterized by high averaged of IPP and Chl a integrated in the photosynthetic layer (Chl phs ) values: 740 mgC m –2 day –1 and 81.40 mg m –2 , respectively. The highest IPP values were observed at sites where Chl a was concentrated in the upper mixed layer or where the subsurface chlorophyll maximum coincided with the pycnocline. Over the area of phytoplankton bloom, the contribution of microphytoplankton (>20 µm) to the total IPP and Chl phs was 92 and 82%, respectively. Contribution of picophytoplankton (<3 µm) to the total PP increased along the depth until reaching the lower margin of layer of photosynthesis, from 3 to 70%, on average. No similar pattern has been observed for vertical distribution of Chl a . This pattern was evidenced by an increase in the chlorophyll specific carbon fixation rate (assimilation number) of picophytoplankton with depth under low insolation conditions.