Fig. 3: Environmental drivers of DO saturation.

a,b, RF partial dependence plots of ice-free mean bottom-water DOsat (a) and its long-term trend (b). a shows the six most important predictor variables identified in the RF model; Δρ, Ased/Vwater, sampling day-of-year and surface-water colour, TP and TN. b includes the top three predictors of the DOsat trend (Δρ trend, Ased/Vwater, sampling day-of-year trend) as well as trends in surface-water colour, TP and TN. Bars summarize statistics of the independent variables and follow the legend of Fig. 2. Numbers rank the permutation importance z-score relative to that of the most important feature. The y axes are the same scale for each subpanel; grey dashed lines mark the intercepts. The complete importance ranking of covariates is shown in Extended Data Fig. 3.