How does rising atmospheric CO2 affect marine organisms?

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Seagrasses Buffering the Negative Effects of OA on Invertebrates

Paper Reviewed
Garrard, S.L., Gambi, M.C., Scipione, M.B., Patti, F.P., Lorenti, M., Zupo, V., Paterson, D.M. and Buia, M.C. 2014. Indirect effects may buffer negative responses of seagrass invertebrate communities to ocean acidification. Journal of Experimental Marine Biology and Ecology 461: 31-38.

Introducing their intriguing research paper, Garrard et al. (2014) write that ocean acidification (OA) may lead to changes in the "attributes of habitat-forming species (such as seagrasses) and other associated communities (epiphytes), thus affecting food and shelter availability for meso-grazers," citing Gartner et al. (2013), while noting that "other indirect effects may occur through changes in biotic relationships (competition, grazing, predation etc.), due to changes in species distribution and abundance," citing Hofmann et al. (2010) and Kroeker et al. (2011, 2013). And in light of these facts, they conducted a study of "how invertebrate assemblages associated with the highly productive seagrass, Posidonia oceanica, respond to natural acidification that occurs at CO2 vents off the coast of Italy."

More specifically, the eight researchers collected pertinent data that incorporated "cold (March), warm (July) and intermediate (November) seawater temperatures, taking into account different morphological features of the P. oceanica canopy, from its maximum development (July), in terms of leaf area index and epiphytic cover, to the minimum cover (March)." And this they did at two control (pH 8.1) locations and two acidified (pH 7.8) locations.

In reporting their findings, Garrard et al. write that "the number of invertebrates collected in acidified stations was almost double that of control stations during the study," and, in fact, they say that "many heavily calcified species appeared to thrive." In conclusion, therefore, they opine that "this highly productive, near-shore habitat may provide refuge to its associated communities from future ocean acidification."

Gartner, A., Tuya, F., Lavery, P.S. and McMahon, K. 2013. Habitat preferences of macro-invertebrate fauna among seagrasses with varying structural forms. Journal of Experimental Marine Biology and Ecology 439: 143-151.

Hofmann, G.E., Barry, J.P., Edmunds, P.J., Gates, R.D., Hutchins, D.A., Klinger, T. and Sewell, M.A. 2010. The effect of ocean acidification on calcifying organisms in marine ecosystems: an organism-to-ecosystem perspective. Annual Review of Ecology, Evolution and Systematics 41: 127-147.

Kroeker, K.J., Micheli, F., Gambi, M.C. and Martz, T.R. 2011. Divergent ecosystem responses within a benthic marine community to ocean acidification. Proceedings of the National Academy of Sciences USA 108: 14,545-14,520.

Kroeker, K.J., Gambi, M.C. and Micheli, F. 2013. Community dynamics and ecosystem simplification in a high-CO2 ocean. Proceedings of the National Academy of Sciences USA: org/10.1073/pnas.1216464110.

Posted 4 May 2015