Some Don’t Like It Hot

As oceans continue to warm and acidify, the survival of the tiny floating young of marine mollusks (Haliotis coccoradiata) and sea urchins (Heliocidaris erythrogramma) looks bleak, researchers report online today in the Proceedings of Royal Society B. Born in the open ocean, these marine invertebrates develop delicate skeletons and shells of calcium before they colonize rougher coastal waters. To investigate how climate change might impact these two marine invertebrates, researchers transplanted eggs of each creature into containers of seawater made slightly more acidic than normal (a pH of either 7.6 or 7.8 rather than 8.2) and up to 4°C warmer. The young mollusks were most affected; unable to calcify their snail-like shells, they formed amorphous blobs (see picture, top right), and most died even after only a 2°C rise in temperature. The sea urchins fared slightly better when matured in water warmed by only 2°C—irrespective of the higher pH—but they formed far fewer spines if the water was 4°C warmer (see picture, bottom right). With ocean temperatures in the South Pacific, which is home to these species, predicted to rise by 2°C by 2030 and even more by the end of the century, these ecologically and economically important species need to adapt or head south to cooler waters to survive.

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