by rising CO 2 . While many species will apparently do fine, even thrive in
an acidified ocean, lots of others will not. Some of the organisms that have
been shown to be vulnerable, like clownfish and Pacific oysters, are
familiar from aquariums and the dinner table; others are less charismatic
(or tasty) but probably more essential to marine ecosystems. Emiliania
huxleyi, for example, is a single-celled phytoplankton—a coccolithophore
—that surrounds itself with tiny calcite plates. Under magnification, it
looks like some kind of crazy crafts project: a soccer ball covered in
buttons. It is so common at certain times of year that it turns vast
sections of the seas a milky white, and it forms the base of many marine
food chains. Limacina helicina is a species of pteropod, or “sea butterfly,”
that resembles a winged snail. It lives in the Arctic and is an important
food source for many much larger animals, including herring, salmon,
and whales. Both of these species appear to be highly sensitive to
acidification: in one mesocosm experiment Emiliania huxleyi disappeared
altogether from enclosures with elevated CO 2 levels.