Exposure to Low pH, Hypoxia, and Anomalously Warm Temperatures Has Implications For Ocean Protection

Warming waters, a result of climate change, are impacting biological processes of marine species (e.g., recruitment, life history, and habitat suitability). When combined with changes to other environmental factors such as the amount of dissolved oxygen, salinity, and pH of surrounding waters, impacts can be significantly different from temperature alone. Marine protected areas (MPAs) are thought to provide some buffer to the impacts of climate change, but their efficacy may be modified when surrounding ecosystems and coastal communities are disrupted.

In this paper, researchers assess exposure to stressful temperatures, dissolved oxygen concentrations, and pH levels across the network of MPAs in California. Key findings include:

• The most common form of stressors came in the form of combined hypoxic and low pH conditions paired with mild temperatures.
• MPAs in Southern California that were exposed to high temperature stress were less likely to be exposed to sub-lethal levels of hypoxia and low pH.
• The relative intensity of low dissolved oxygen and low pH across different parts of California was consistent across several years of monitoring.

The findings from this study have important implications for ecological and human communities within and around California’s MPA system. Beyond California, these results provide more information regarding the utility of MPAs as conservation tools under climate change and guidance on designing a network structure of climate-smart MPAs.

Read the full paper here.

Reference

Hamilton, S., Kennedy, E., Zulian, M., Hill, T., Gaylord, B., Sanford, E., Ricart, A., Ward, M., Spalding, A., Kroeker, K. (2023) Differential exposure to low pH, hypoxia, and anomalously warm temperatures across a marine protected area network has implications for ocean protection. ICES Journal of Marine Science. https://doi.org/10.1093/icesjms/fsad120