Effects of Nitrogen Emissions on Fish Species' Richness across the World’s Freshwater Ecoregions

This study approaches this issue by establishing regionalised species' sensitivity distributions (SSDs) of freshwater fish against N concentrations for 367 ecoregions and 48 combinations of realms and major habitat types globally. Subsequently, effect factors (EFs) were derived for LCA to assess the effects of N on fish species richness at a 0.5 degree × 0.5 degree resolution. Results show good SSD fits for all of the ecoregions that contain sufficient data and similar patterns for average and marginal EFs. The SSDs highlight strong effects on species richness due to high N concentrations in the tropical zone and the vulnerability of cold regions. This study reveals the regional differences in sensitivities of freshwater ecosystems against N content in great spatial detail and can be used to assess nutrient-induced impacts in LCA more precisely and comprehensively.