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Mussels Better Protected from Sea Stars in a CO2-Enriched World

Paper Reviewed
Keppel, E.A., Scrosati, R.A. and Courtenay, S.C. 2015. Interactive effects of ocean acidification and warming on subtidal mussels and sea stars from Atlantic Canada. Marine Biology Research 11: 337-348.

Many biologists have long been concerned about the potential consequences of the historical and still-on-going increase in the atmosphere's CO2 concentration on both the degree of atmospheric warming and the concomitant increase in ocean acidification that these phenomena may cause to occur. And driven by these concerns, Keppel et al. (2015) sought to determine the potentials of these two phenomena to impact the feeding of sea stars (Asterias rubens) -- which they collected from Antigonish Harbour, Nova Scotia, Canada -- on mussels (Mytilus edulis) that they collected from the same location.

Adjusting the degree of ocean water acidification and temperature to values predicted by climate alarmists to likely prevail at the end of the current century, the three researchers found the sea stars to be negatively affected in terms of growth rate, consumption rate and calcified mass by the lower pH, with growth further reduced by the 4°C higher temperatures projected to prevail throughout the summer months of July and August. Mussel growth rates, on the other hand, were positively affected by the lowered pH and showed no response to the higher temperatures within the tested range.

In light of these findings, i.e. that M. edulis may benefit from lower predation pressure due to a combination of lower sea star consumption rate and their own faster attainment of larger size-determined refuge -- with the ultimate result that "ocean acidification and warming may thus lead to altered sea star and mussel populations and associated changes in community structure" -- the work of Keppel et al. suggests that the mussels they studied, as well as those of other locations, may fare far better in a CO2-enriched world of the future than they do currently.

Posted 10 July 2015