LAUSR

Over the vast open ocean, vital nutrients for phytoplankton growth in the sunlit surface layer are largely provided through physical transport from deep waters, but some nutrients are also provided through atmospheric deposition of desert dust. The extent and magnitude of dust-mediated effects on surface ocean ecosystems have been difficult to estimate globally. In this work, we use global satellite ocean color products to demonstrate widespread responses to atmospheric dust deposition across a diverse continuum of phytoplankton nutritional conditions. The observed responses vary regionally, with some areas exhibiting substantial changes in phytoplankton biomass, whereas in other areas, the response reflects a change in physiological status or health. Climate-driven changes in atmospheric aerosols will alter the relative importance of this nutrient source. Description Editor’s summary Most of the nutrients that fuel primary production in the oceans come from water upwelled to the surface from deeper depths, but atmospheric aerosols have long been recognized as another potential source. Westberry et al. used measurements of ocean color made by satellites to show that the global distribution of phytoplankton is affected by dust deposition, with impacts that vary from region to region. Climate change is expected to alter the relative importance of this mechanism. —H. Jesse Smith The deposition of nutrients from the atmosphere to the surface ocean is reflected by global phytoplankton biomass distributions.