Assess understanding of the causes of ocean acidification (atmospheric CO2 uptake, upwelling, freshwater inputs), core carbonate chemistry (pH, dissolved CO2, HCO3-, CO32-, total alkalinity, aragonite/calcite saturation), and ecological effects on marine organisms and food webs (calcification, larval development, behavior, ecosystem services). Includes conceptual explanations, basic quantitative interpretation of pH/Ω data, and evaluation of mitigation or adaptation approaches.