Nitrogen dose-response relationships: benthic algae and macroinvertebrates in running water

Abstract

Nitrogen deposition affects freshwater biodiversity in two ways: by contributing to acidification via nitrate in runoff, and by acting as a nutrient. We used data for two organism groups, benthic algae (224 sites) and benthic invertebrates (62 sites), to test if N as a nutrient affects the species numbers of these groups in running water. Neither of these groups showed significant relationships with nitrogen, except for a positive relationship between nitrate concentration and the number of blue green algae with heterocysts. It is not possible to set a critical limit for N as a nutrient, at least for these organism groups in running water.