University of Washington Study uses the Integrated Ecosystem Assessment Approach to Evaluate a Biological Indicator for Ocean Acidification Assessment in Marine Management

Increasing ocean acidification (OA), caused by increased amounts of carbon dioxide being absorbed in oceans, can impact marine life and their ecosystems.

As oceans chemically change, forms of marine life that grow calcium carbonate shells and structures are more likely to be harmed by ocean acidification. One well-studied group of such organisms is pteropods, a diverse group of free-swimming marine snails found throughout the world’s oceans.

Recently published research led by the University of Washington in partnership with NOAA’s Ocean Acidification and Integrated Ecosystem Assessment (IEA) Programs presents pteropod shell dissolution as the first important biological indicator for low-cost assessment of the effect of ocean acidification on marine ecosystems. As the socioeconomic challenges of changing ocean chemistry continue to grow in coming decades, the availability of such straightforward and sensitive metrics of impact will become indispensable.

Dr. Nina Bednaršek (University of Washington School of Marine and Environmental Affairs) led the study that links the increasing pteropod dissolution rates to OA in the California Current ecosystem. Seawater contains a form of calcium carbonate called aragonite, which pteropods use to build their shells. Dr. Bednaršek and her colleagues first showed that as OA reduces seawater concentrations of aragonite, pteropod shell dissolution increases, and survival decreases. The research team then compared the information content of OA/pteropod studies to other studies of the ecological condition of the California Current ecosystem, using previously established indicator selection criteria that have been adopted by the California Current IEA team. The researchers found pteropod shell dissolution to be one of the most robust indicators of the overall integrity of the ecological community.

Ocean Acidification CollagePteropod (Limacina helicina) Photos:
  • Top left - Pteropod with severe shell dissolution from an offshore region of the California Current ecosystem light microscopy image)
  • Top right - Healthy pteropod from an offshore region of a California Current ecosystem (light microscopy image)
  • Bottom left - Pteropod with severe shell dissolution across the entire shell found in the coastal waters of the California Current ecosystem in areas affected by ocean acidification (scanning electron image)
  • Bottom right - Pteropod with an intact shell from the regions not affected by ocean acidification (scanning electron image)
    Photo credit: Dr. Nina Bednaršek (University of Washington School of Marine and Environmental Affairs)

Increasing levels of ocean acidification may lead to adverse repercussions along the food chain and, eventually, at local and global economic levels. Based on the rate of pteropod shell dissolution, scientists and decision-makers will be able to use this information to develop new criteria to quickly evaluate and implement mitigation measures for any negative effects of ocean change at environmental, social, and economic levels.

Dr. Richard Feely, a co-author on the study and an OA expert at the NOAA Pacific Marine Environmental Laboratory, highlighted the importance of the IEA process as a contributor to the findings that show pteropods can be valuable indicators of the effects of ocean acidification on ecological integrity within an ecosystem-based management approach: “I am certain [these IEA] approaches for using pteropods as a simple, practical indicator of ocean acidification stress will prove to be useful in future OA studies.”

To read “New ocean, new needs: Application of pteropod shell dissolution as a biological indicator for marine resource management on fish forecasting in Ecological Applications” in Ecological Indicators:

For more information on the Integrated Ecosystem Assessment Program:

For more information on the Integrated Ecosystem Assessment California Current Program: