Improved Estimates of Primary Production in the Chukchi Sea

Changes in the Arctic Ocean have been dramatic, particularly with respect to the extent, thickness, and ages distribution of sea ice. Recently, the preponderance of first-year sea ice and the proliferation of melt ponds in the Chukchi Sea has dramatically increased light transmission to the upper water column and stimulated massive under-ice blooms. Unfortunately, because of their location under the ice, these blooms are largely invisible to the satellites most often used to estimate large-scale rates of net primary production (NPP) in Arctic waters. In addition, once the sea ice finally retreats in late spring, surface chlorophyll a (Chl a) concentrations are often very low. As a result, rates of NPP on the Chukchi Shelf measured from satellites are likely to severely underestimated. Here we use large-scale measurements of pre-bloom and post-bloom nutrient concentrations across the Chukchi shelf, along with information on advection of waters through Bering Strait and across the Chukchi shelf, to estimate rates of nutrient consumption and primary production beneath the sea ice. These estimates are combined with improved satellite-based information on phytoplankton abundance and NPP in ice-free water using regional Chl a and NPP algorithms to provide a better understanding of spatial and interannual variability in annual NPP throughout the Chukchi Sea.