Ocean acidification may hamper food web’s nitrogen-fixing heroes
Earlier experimental glitches rearing Trichodesmium microbes may explain past conflicting results
SEA CHANGE A rethink of earlier studies suggests trouble ahead for a major player in ocean nutrient cycles, the nitrogen-fixing Trichodesmium microbes, which can grow in abundance as seen is this image (pale streaks).
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A hard look at experimental setups may start to explain dueling predictions on whether ocean acidification will boost, or choke, vital marine nitrogen fixers. So far, the new look trends toward choking.
As people release more and more carbon dioxide into the air, the ocean takes up the gas and edges closer toward acidity. In these shifting waters, marine microbes called Trichodesmium could falter in adding nitrogen, a critical input for marine food webs, says Dalin Shi of Xiamen University in China. And the problem could be exacerbated in acidifying seas where iron is scarce — for instance, in wide swaths of tropical and subtropical waters such as the southern Atlantic and Pacific oceans, Shi and colleagues report April 27 in Science.
The question of how Trichodesmium cyanobacteria are reacting to the changing ocean makes a big difference in predicting
