A predicted worldwide fall in ocean alkalinity could have subtle effects on a small shoreline snail, shutting down one of its best defenses against crab predators, researchers say.
The surface waters of the world's oceans are slightly alkaline. As human activity continues to add carbon dioxide to the atmosphere, however, increasing amounts of the greenhouse gas dissolve in the oceans, pushing seawater toward acidity.
The common periwinkle (Littorina littorea) normally grows a thicker shell when living among predators, says Simon Rundle of the University of Plymouth in England. In lab tests, he and his Plymouth colleagues found that a big increase in seawater acidity had little effect on periwinkles' shells—except when a predatory c