A study of prehistoric coral reefs shows that these shallow-water congregations of corals, fish and shell fish aren’t just diversity magnets, they actually create new species.
And that is worrisome news in the face of climate change, which rising ocean temperatures and higher carbon dioxide levels, threatens to wipe out the world’s coral reefs by 2050.
The paper, published Thursday in the journal Science, looks at a large database of sea floor fossils, the Paleobiology Database, beginning in the Cambrian period, about 540 million years ago. The researchers, at the Leibniz Institute for Research on Evolution and Biodiversity at Humboldt University in Berlin and the University of Chicago, compared the number of new species and genera that first appeared in coral reefs with those that first appeared in shallow water.
There’s long been debate among scholars over whether coral reefs simply attract lots of diversity animals and plants, or whether these complex ecosystems also contribute to the evolution of new species. The researchers found that since the Cambrian explosion of new forms of life on Earth, coral reefs have been key ‘evolutionary cradles’ for new species, in the words of the paper. Not only that, but coral reefs are prolific exporters of biological diversity to other ocean environments, the research found.
With coral reefs so important to continued diversity, the current destruction of today’s reefs is troubling. Coral reefs support fully a quarter of all marine life. However, the effects of global warming are likely to be devastating to reefs, with worse to come.
Warming first increases water temperature, causing a condition called bleaching in which corals lose the symbiotic algae that allow them to survive. In addition, more carbon dioxide dissolving into the oceans makes the water more acidic, which causes corals’ exoskeletons to dissolve.
By Elizabeth Weise
Photo: Detail of a fossil reef from Vanuatu. (By W. Kiessling)