Phytoplankton response to an intense dust storm in the Tasman Sea in September-October, 2009

Here we present a detailed analysis of the marine biological response in the Tasman Sea (25-40ºS, 150-170°E) after the 'Red Dawn' dust storm, which was one the largest recorded in SE Australia in the last 70 years. We examine the impact of dust-derived nutrients deposited to the ocean surface on satellite-derived estimates of phytoplankton biomass as indicated by surface chlorophyll-a. We have simulated contemporaneous atmospheric dust load and deposition over the adjacent ocean using a regional dust transport model that provides daily data from September to December 2009. The phytoplankton response was confined to the region south of 30ºS, with the greatest positive anomalies (>0.6 mgm-3) occurring south of 35ºS, even though deposition was recorded further north. Contrary to previous reports of little biological impacts from dust storms in the Tasman Sea, our results suggest the regional phytoplankton can respond strongly to inputs of aeolian nutrients during the Austral spring if deposition is strong and ocean conditions are favourable