View article

Stream liming can alleviate the effects of anthropogenic acidification but itself constitutes a substantial ecosystem‐level perturbation. Acidity in the humic streams of northern Sweden largely arises from natural causes but liming is extensively practised, with uncertain ecological outcomes.

We investigated macroinvertebrate assemblage structure and leaf‐litter decomposition in seven humic Swedish streams, each of which is limed at a single point using a dosing tower. Grey alder Alnus incana leaves were enclosed in replicate fine (mesh size 0·5 mm) and coarse (10 mm) mesh bags at three locations in each stream: upstream of the dosing tower, in the transitional ‘mixing zone’ immediately downstream of the tower, and at a site further downstream where the lime powder is completely dissolved, with marked changes to water chemistry. Benthic macroinvertebrate assemblages were characterized from each site …