Fig. 11

Forest plot showing maximum negative effects on chironomid emergence during the study period in each included study. The size of the squares is proportional to the weight of the studies, which is based on the number of replicates. Liber (1998) and Duchet (2015) reported separate emergence data for different chironomid species, but to avoid statistical dependence we have used data for only one species. To obtain a conservative estimate of negative effects the species showing the least negative effect was selected (results do not change significantly if other species are used). Data in the figure represents five regions (four in Europe, one in North America). Study labels refer to short reference and study name information as recorded in Additional file 6