Managing Local Coastal Stressors to Reduce the Ecological Effects of Ocean Acidification and Warming

Anthropogenic activities have increased the number of stressors acting on ecosystems. When multiple stressors act simultaneously, there is a greater probability of additive, synergistic and antagonistic effects occurring among them. Where additive and synergistic effects occur, managers may yield disproportionately large benefits where they first act upon synergies. Stressors act, however, at different spatial and temporal scales. Global stressors (e.g., ocean acidification and warming) tend to change slowly over long periods of time, although their intensity and effects are contingent on local conditions. On the other hand, local stressors tend to change rapidly over shorter, more defined spatial and temporal scales. Hence, local stressors can be subject to a greater degree of control through local management (e.g., eutrophication and overfishing) while global stressors are characterized by an intrinsic inertia whose effects last for decades, if not centuries. Although the reduction of carbon emissions is an international priority for managing global stressors, it requires international agreements and management applications that take considerable time to develop. Managers, however, may ‘buy time’ by acting on stressors whose governance is local (e.g., reducing nutrient input) and are known to synergize with global stressors (e.g., enriched CO2). Such local actions may potentially disrupt synergies with the more slowly changing global stressors that can only be reduced over longer time scales.