Contrasting effects of anthropogenic and natural acidity in streams: a meta-analysis

摘要: Large-scale human activities including the extensive combustion of fossil fuels have caused acidification freshwater systems on a continental scale, resulting in reduced species diversity and, some instances, impaired ecological functioning. In regions where acidity is natural, however, and functioning seem to be less affected. This contrasting response likely more than one explanation possibility adaptation organisms exposed natural over evolutionary time scales differential toxicity due dissimilarities water chemistry other pH. However, empirical evidence supporting these hypotheses equivocal. Partly, this because previous research has mainly been conducted at relatively small geographical scales, information context generally scarce. Our goal was test whether anthropogenic stronger negative effects acidity. Using meta-analytic approach based 60 datasets, we show that macroinvertebrate richness decomposition leaf litter—an important process streams—tend decrease with increasing across both categories. Macroinvertebrate richness, declines three times rapidly it agreement hypothesis differences chemistry. By contrast, loss differs little between categories, probably increases biomass taxa remaining low pH compensate for losses functionality would otherwise accompany from acidic systems. example illustrates how stressors can differ markedly their aspect