Interannual variability of Emiliania huxleyi blooms in the Barents Sea: In situ data 2014-2018.

Using in situ data of 2014-2018, the summers Emiliania huxleyi blooms in the Barents Sea were studied. The blooms were recorded in the upper mixed layer in July and August every year, during which they spread to cover large areas and were associated with Atlantic waters. The E. huxleyi abundance revealed interannual variability, with the highest values (up to 12 × 10 cells/L) in July 2016. Bloom is characterized by a sharp seasonal thermocline, water surface temperature of about 7.14-11.7 °C, low silicate (0.45 ± 0.08 μM) and nitrogen (0.74 ± 0.16 μM) concentration, high phosphorus concentration (0.09 ± 0.01 μM) and nitrogen to phosphorus ratio significantly below the Redfield ratio. Data confirming the hypothesis of limiting the growth of diatoms by nitrogen concentration are presented. When E. huxleyi bloomed, its biomass exceeded 70% of the total phytoplankton biomass, species diversity was low, and diatoms were practically absent, and dinoflagellates were usually represented by large species.