An international team of scientists from the Carnegie Institution for Science, Rice University and other institutions has performed the first experiment to manipulate seawater chemistry in a natural coral-reef community to determine the effect that excess carbon dioxide released by human activity is having on coral reefs. The research, which is published in this week's issue of Nature, was conducted in a lagoon on the southern Great Barrier Reef in Australia in 2014. By controlling the alkalinity on a portion of the reef, the team was able to examine how fast the reef is growing today and compare that with growth rates in less acidic conditions that existed prior to the Industrial Revolution. 

"Our work provides the first strong evidence from experiments on a natural ecosystem that ocean acidification is already causing reefs to grow more slowly than they did 100 years ago," said study lead author Rebecca Albright, a marine biologist in Carnegie's Department of Global Ecology in Stanford, Calif. "Ocean acidification is already taking its toll on coral reef communities. This is no longer a fear for the future; it is the reality of today." 

The research team included Rice's Kai Zhu, an expert in ecological statistics who joined Rice as a Huxley Faculty Fellow in the Department of BioSciences in January following a postdoctoral appointment at Carnegie's Department of Global Ecology.

"The data analysis for the experiment was complicated by the natural variation of conditions in the reef," Zhu said. "Statistically speaking, there was a great deal of noise in the data, and as scientists we needed to filter out the noise so that we could examine only the signal, the change in the growth rate that resulted from the change in alkalinity."