Delivery of terrigenous nutrients from rivers and coastal erosion sustain up to one third of Arctic Ocean Net Primary Production
Abstract:
In our study, we explicitly simulate the impact of terrigenous carbon and nutrient inputs on Arctic NPP, using an ocean-biogeochemical model and a novel, spatially and seasonally resolved, observation-based forcing data set of carbon and nutrient inputs from rivers and coastal erosion. For nitrogen (N), which is the limiting nutrient in the Arctic Ocean, we quantified the average contemporary inputs from Arctic rivers and coastal erosion at 1 Tg N yr-1 and 1.6 Tg N yr-1, respectively. The evaluation of our model results confirms that these inputs are necessary to reproduce the observed Arctic NPP, which is otherwise substantially underestimated. Our simulation results show that terrigenous nutrient inputs sustain 36 ± 14 % (21±8 Tg N yr‑1) of annual Arctic NPP. This proportion significantly exceeds earlier estimates because of high simulated recycling rates and because of the inclusion of inputs from coastal erosion. Our results further suggest that changes in terrigenous nutrient fluxes due to climate change are one of the determining factors of the future of primary production and associated food webs in the Arctic Ocean.