Nitrogen transfer from sea to land via commercial fisheries

摘要

Human activity has dramatically altered global nitrogen fluxes, nearly doubling the nitrogen export from land to coast(1). Fertilizer run-o V accounts for much of this increase(2,3). The role of commercial fisheries in altering fish stocks has been explored(4-6), but their effect on the return of nitrogen from coastal oceans to land is less well known. Here we quantify the nitrogen return to land via fisheries and compare it with nitrogen fertilizer inputs into the coastal ocean regionally and over time. We find that both fertilizer run-off into the ocean and fishery removal of nitrogen have increased over the past four decades, but the increase in nitrogen input has been faster. Although our estimate for the ratio of nitrogen return to nitrogen input has therefore decreased over time from about 60% in 1960 to about 20% in 2000, we conclude that fishery harvest is a significant, and currently underappreciated, aspect of anthropogenic nitrogen flux in many coastal regions.