Global negative effects of drought on instream invertebrate communities

Abstract

Global climate change has led to more frequent and severe droughts, which can negatively affect instream invertebrate communities, but we lack a perspective on the global patterns and drivers of such drought effects. Here, using meta-analysis, we synthesized 997 paired observations extracted from 94 peer-reviewed publications to assess how drought affects the biomass, density, taxonomic richness, and diversity (Shannon–Wiener, Simpson, and Pielou indices) of instream invertebrates at a global scale. We found that (i) drought significantly decreased instream invertebrate density and taxonomic richness by an average of 4.9 and 5.0%, respectively, had marginal negative effects on Shannon–Wiener index, but did not affect biomass, Simpson index or Pielou index; (ii) the effects of drought on instream invertebrate biomass, density, and diversity were not affected by taxonomic level, indicating the robustness of our results; and (iii) stream water physiochemical characteristics such as water flow velocity, pH, conductivity, discharge, total nitrogen concentration, and chlorophyll-a concentration were important moderator variables of drought effects on instream invertebrate communities. Overall, our results clearly showed the global patterns and driving factors of drought effects on instream invertebrate biomass, density, richness, and diversity, which helps scientists better understand the responses of instream invertebrate communities under ongoing global climate change.