Scatter Plot from Scientific Research

Bottom-water oxygen concentrations classified by maximum depth across 7,394–8,288 lakes, depending on data availability. Annual class-medians (dots) were computed from ice-free season lake–year mean DO corrected for bias toward mid-season sampling (Methods). GAM smooths were weighted by inverse variance to account for uncertainty at low sample counts. Shaded areas represent 95% confidence intervals (CIs). Legend labels define class boundaries. Dashed and dotted lines mark hypoxia (DO < 2 mg l -1 ) and anoxia (DO < 0.5 mg l -1 ), respectively.

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