Coastal Ocean Acidification

Ocean acidification is driven predominantly by ocean uptake of atmospheric carbon dioxide (CO2), resulting in global-scale changes in ocean chemistry with predictions of broad-scale ecosystem impacts. Coastal acidification, which refers to a pH decline over decadal or longer time scales, resulting not only from atmospheric CO2, but also from changes in coastal biogeochemical and hydrographic processes, is recognized as the coastal manifestation of ocean acidification.

Multi-Stressor Research

Climate change is exacerbating existing environmental stressors—such as hypoxia, harmful algal blooms, and ocean acidification—through changes to the fundamental drivers of ecosystems—temperature, precipitation, seasonal cycles, and biogeochemistry. These changes impact processes—such as oxygen, nutrient and carbon cycling, respiration rates, stratification, ocean circulation, upwelling, and mixing—with implications for the prevalence, severity, and duration of harmful algal blooms, ocean acidification, and hypoxic events. Understanding how these multiple stressors interact and subsequently impact species, habitat assemblages, and ecosystems is critical for place-based management.

Harmful Algal Blooms and Ocean Acidification Workshop.
Workshop to advance national and regional research on ocean acidification and harmful algal blooms as co-stressors in coastal ecosystems.

Understanding Multi-Stressor Impacts on Marine Ecosystems Under Climate Change.
NOAA funded projects addressing the need to understand interactions between ocean acidification and HABs and their impacts on coastal ecosystems, communities, and economies.

Ocean Acidification Impacts on Coastal Ecosystems

The complex and large-scale nature of these environmental stressors requires a coordinated, interdisciplinary ecosystem approach. Past and current research efforts and programs typically have focused on understanding the impact of single stressors on species and ecosystems. However, understanding the impacts and relationships among multiple stressors remains elusive, yet critical, given the potential for unexpected interactions between multiple stressors, the possibility of irreversible ecosystem effects, and the need to manage and anticipate such possibilities. The NCCOS Competitive Research Program has funded 12 projects that address the impacts of ocean acidification on coastal ecosystems. Our active projects are listed below.