Pearson correlations (r) and Gaussian squared correlation coefficients (Gauss. r2(adj)) of diatom relative abundance versus measured environmental variables considered to represent a mixture of natural and anthropogenic components.

Gaussian optima are marked as to whether they are lower than the minimum (-) or higher than the maximum (+) stressor values for Great Lakes catchments (i.e. actual optima are lower or higher, respectively). The top 25 taxon-stressor relationships are presented, sorted by smallest P value. N = number of observations in samples. A full list of the significant taxon-stressor relationships is in S2 Table.