Fig. 6
Principal component analysis of the East African SPEARpesticides index and those environmental variables that (marginally) significantly correlated with any of the investigated bioindicators. The first principal component (horizontal axis) explains 60.7% of the overall variation and was considered to represent a gradient of stream types. The second principal component (vertical axis) additionally explains 14.7% of the overall variation and was considered to represent a gradient of high water level. Each point represents a stream (identified by its number, see Additional file 2: Table S4), colors refer to the average SPEARpesticides value obtained from each stream