Fig. 2

Evidence availability and mean effect sizes for the U.S. (states and the District of Columbia). Maps show the number of cause-effect pairs (N) included in the narrative synthesis and meta-analysis for the stressor-response relationships: a TN-benthic chl-a, b TP-benthic chl-a, c TN-sestonic chl-a, and d TP-sestonic chl-a. White stars indicate effect sizes < 0