Can seagrass help ameliorate ocean acidification?

Sarah Giddingsnews

This important question is addressed in a new paper “Expected limits on the ocean acidification buffering potential of a temperate seagrass meadow,” led by David Koweek at the Department of Global Ecology, Carnegie Institution for Science, Stanford. A press-release from the Carnegie Institution and a blog post by David Koweek do an excellent job summarizing the paper in detail.

This paper is the culmination of an interdisciplinary collaboration amongst seagrass ecologists, chemists, climate scientists, and physicists to address the buffering potential of seagrass meadows against ocean acidification, a critical topic as we face a changing climate. We employed a numerical box model coupled with hydrodynamics and a complex bio-geochemical seagrass/chemistry model to investigate the ability for an estuarine seagrass meadow to buffer the acidity of incoming oceanic water (i.e., to counteract ocean acidification). Overall, buffering capacity was found to be relatively weak, about equivalent to turning back the clock a few decades, which is a small offset to the 150 years of ocean acidification that has already occurred and is worsening. Thus the results suggest that while buffering does occur, it is not enough for long-term ocean acidification mitigation. However, there were brief periods of time when buffering capacity was high; that coupled with new information about how organisms can adapt to changing environments, as well as other potential mitigation approaches, provide potential opportunities to use seagrass as part of a broader strategy to ameliorate local ocean acidification in estuaries. The model for this work was parameterized specifically to Tomales Bay, a northern California large estuary, however the resulting publicly available box-model is designed so that it can be tested under varying conditions.

This work is a contribution of the Seagrass Ocean Acidification Amelioration Workshop of the Bodega Marine Laboratory, financial support for which was provided by California Sea Grant and the Coastal & Marine Sciences Institute of the University of California, Davis. Partial support was provided by the National Science Foundation.