Increases in anthropogenic emissions of sulfur (S) and nitrogen (N) have resulted in increases in the associated atmospheric deposition of acidic compounds. In sensitive watersheds, this deposition has initiated a cascade of negative environmental effects on aquatic ecosystems, resulting in a degradation or loss of valuable ecosystem goods and services. Here, we report the activities of an expert workgroup to synthesize information on acidic deposition-induced aquatic acidification from the published literature and to link critical load exceedances with ecosystem services and beneficiaries, using the Stressor–Ecological Production function–Final Ecosystem Services (STEPS) Framework and the Final Ecosystem Goods and Services Classification System (FEGS-CS). Experts identified and documented the sensitive aquatic ecosystem ecological endpoints valued by humans, and the environmental pathways through which these endpoints may experience degradation in response to acidification. Beneficiary groups were then identified for each sensitive ecological endpoint to clarify relationships between humans and the effects of aquatic acidification, and to lay the foundation for future research and analysis to value these FEGS.
