Interannual Variability of Primary Production in the East Siberian Sea

Abstract

Interannual variability (2002–2018) of primary production, surface seawater temperature (T0), photosynthetically active radiation (PAR) and ice cover area in the East Siberian Sea (ESS) was studied based on the data of the MODIS-Aqua ocean color scanner. The annual total primary production (PPtot) decreased by 1.7 TgC over 17 years. The multi-year negative trend in PPtot was 0.1 TgC y–1 (1.38% y–1). The decrease in PPtot was accompanied by the decrease in the area-specific primary production (IPP). Over the investigated period the annual mean IPP decreased by 13 mgC m–2 d–1. The multi-year negative trend in IPP was 0.76 mgC m–2 d–1 y–1 (0.84% y–1). The decrease in PPtot and IPP was accompanied by statistically insignificant increase in T0 (R2 = 0.09) and statistically significant decline in PAR (R2 = 0.29). Over the 17 years, T0 in ESS increased by 0.68°С (0.04°С y–1 or 3.2% y–1) and PAR declined by 3.4 Ein m–2 d–1 (0.2 Ein m–2 d–1 y–1 or 1.9% y–1). The ice-free area slightly diminished during the study period (R2 = 0.10) by 64.94×103 km2. The statistically insignificant negative multi-year trend in the ESS ice-free area was 3.82 × 103 km2 y–1 (0.87% y–1). Long-term variability in PPtot in ESS from 2002 to 2018 depended not only on the decrease in the ice cover but also on PAR level and IPP.