An Ecological Risk Analysis of Ocean Acidification in the California Current

The oceans absorb approximately 30% of carbon emitted into the atmosphere, causing temperature changes and ocean acidification. However, the realized impact that ocean acidification will have on marine ecosystems remains largely unknown. Here, we adopt a risk-based framework for screening species most likely to be affected by changes in pH based on exposure, sensitivity, and life stage analysis. The risk metric adapts the existing approach of determining sensitivity and exposure by adding a third axis of life stage elasticity. This approach allows for an investigation of the risk faced by key species in the California Current accounting for the importance of each life stage for species’ success. The California Current is an ideal study system, as low levels of carbonate saturation already exist within the near-shore environment due to upwelling and species currently experiencing low pH will experience even lower levels earlier than those in other regions. Species were selected based on ecological and/or economic importance.  Results from this analysis applied to seven species from zooplankton to crustaceans and fish, reveal differences in risk based on life histories and physiological tolerance. This work reveals information gaps needed to precisely forecast ecological changes from acidification, and to more effectively assess risk.