Climate patterns and phytoplankton dynamics in Antarctic latent heat polynyas

Abstract

Seasonal coherence between satellite‐derived phytoplankton parameters (chlorophyllaconcentration (Chl) and phytoplankton bloom initiation time (BIT)), environmental variables (sea ice concentration, surface solar radiation, and wind speed), and climate patterns (El Niño 3.4, the Southern Annular Mode, the Pacific South America pattern, the semiannual oscillation, and the wave‐3 stationary pattern) was investigated in four latent heat polynyas (Amundsen Sea, western Ross Sea, Dumont d'Urville, and Prydz Bay) using data corresponding to 1998–2006 phytoplankton growing seasons. In general, polynyas in the western sector (i.e., Amundsen Sea and western Ross Sea) had a greater sea ice cover, lower solar radiation levels, higher and more variable Chl, and more variable and delayed (i.e., high BIT) phytoplankton blooms. Differences in Chl and BIT were mainly attributed to differences in water stratification and interannual variability of sea ice concentration caused by ice shelf calving events in the Ross Sea. Changes in solar radiation reaching the sea surface played an important role in determining phytoplankton blooms in the western Ross Sea and Prydz Bay. Stronger winds tend to benefit development of phytoplankton blooms in polynyas having more stratified waters. Sensitivity of phytoplankton to climate variability in polynyas under investigation was highly influenced by the polynya size during summer (e.g., Chl in Dumont d'Urville and BIT in the western Ross Sea). Also, the response of Chl to the same climate pattern changed with the polynya's location (e.g., correlation between Chl and El Niño 3.4 in Amundsen Sea (positive) and Dumont d'Urville (negative)).