Variations of net primary productivity and phytoplankton community composition in the Indian sector of the Southern Ocean as estimated from ocean color remote sensing data

[摘要] Phytoplankton population dynamics play an important role inbiogeochemical cycles in the Southern Ocean during austral summer. Recentenvironmental changes such as a rise in sea surface temperature (SST) arelikely to impact on net primary productivity (NPP) and phytoplanktoncommunity composition. However, their spatiotemporal relationships are stillunclear in the Southern Ocean. Here we assessed the relationships betweenNPP, dominant phytoplankton groups, and SST in the Indian sector of theSouthern Ocean over the past decade (1997–2007) using satelliteremote sensing data. As a result, we found a statistically significantreduction in NPP in the polar frontal zone over the past decade duringaustral summer. Moreover, the decrease in NPP positively correlated with thedominance of diatoms (Kendall's rank correlation τ = 0.60)estimated by a phytoplankton community composition model, but notcorrelated with SST. In the seasonal ice zone, NPP correlated with not onlythe dominance of diatoms positively (τ = 0.56), but also thedominance of haptophytes (τ = −0.54) and SST (τ = −0.54)negatively. Our results suggested that summer NPP valueswere strongly affected by the phytoplankton community composition in theIndian sector of the Southern Ocean.

[学科分类] 地球化学与岩石