and society is a challenging endeavor due to the complexity and dynamic nature of marine ecosystems and the likelihood that the effects of acidification will differ among species and ecosystems. Furthermore, interaction of stresses from acidification with other simultaneous stressors such as warming, eutrophication, and deoxygenation remains poorly understood.
Assessing the socioeconomic impacts from ocean acidification represents an even greater challenge. Globally, fish represented nearly 17% of society’s animal protein intake in 2009 and 6.5% of all protein consumed and it is uncertain how ocean acidification will affect these resources. Although the broader potential socioeconomic impacts of ocean acidification are poorly known, impacts have already been observed on key industries like shellfish aquaculture. For example, the Pacific Northwest aquaculture industry, which is estimated to contribute approximately 270 million dollars per year and 3,200 jobs to local coastal communities, has recently experienced major failures in its oyster hatcheries due to effects of low pH waters on oyster larvae. Whereas these low pH values are due in large measure to upwelled water with low pH, the effects seen on larvae illustrate potential consequences of acidification resulting from entry of atmospheric CO2 to the oceans. It is also important to point out that, at these sites in the Northwest and at other coastal sites influenced by runoff from land, effects of eutrophication on CO2 content and pH are likely to be substantial. Thus, the effects of rising atmospheric CO2 on pH are compounded by other anthropogenic influences. In response to threats posed by reduced pH (from any sources) some aquaculture operations are currently adapting their practices by monitoring pH changes in their water intake systems and timing water intake during favorable conditions. However, many other oyster farms lack the ability to monitor or predict such changes and will need to develop these capabilities. Many options to offset reduced pH and carbonate saturation in situations like oyster aquaculture (or other mariculture operations occurring around the globe) seem impractical due to the energy costs (and release of CO2) associated with adding compounds like lime to increase pH.
The build-up of coral skeletons, which form the structural basis for coral reef ecosystems, is also pH-sensitive. These marine ecosystems support vast biodiversity and generate large amounts of dietary protein in the form of fish and shellfish, and provide physical protection from storms in coastal regions. Deep water coral communities serve as important nursery habitats for many species. How the direct and indirect effects of ocean acidification will translate into the health and sizes of fish and shellfish populations and, thereby, into food production, is an important but unanswered question in the broad arena of socioeconomic impacts of ocean acidification.