Coral bleach-out in Belize.

7. Erickson, E. H. & Werner, F. G. Ann. Entomol. Soc. Am. 67, 903–908 (1974). 8. Clausen, C. P. Annu. Rev. Entomol. 21, 343–368 (1976). 9. Borg-Karlson, A. K. Phytochemistry 29, 1359–1387 (1990). 10.von Frisch, K. Bees, their Vision, Chemical Senses, and Language (Cornell Univ. Press, Ithaca, NY, 1950). 11.Southwood, T. R. E. Ecological Methods (Chapman & Hall, London, 1978). depths. Heavy mortality occurred in the other species as well (Fig. 1a). Similar patterns were seen throughout a 375-km area of the central lagoon. High water turbidity and the broad depth range of these effects suggest that temperature, rather than solar radiation, was primarily responsible for the bleaching and subsequent coral mortality. Ag. tenuifolia had been the dominant space-occupier on lagoonal reefs since the late 1980s. At that time, the previous dominant, Acropora cervicornis (staghorn coral), was almost eliminated by white-band disease (a presumed bacterial infection unrelated to bleaching), permitting Ag. tenuifolia to increase opportunistically. To determine whether similar events occurred in the past, we extracted 12 cores by hand from nine reefs in the central lagoon. These push-cores penetrated several metres into the uncemented reef frameworks. Radiocarbon analysis yielded a maximum uncorrected C date of more than 3,000 yr. The cores showed continuous domination of lagoonal assemblages by Ac. cervicornis, with no widespread Acropora mortality, and no replacement by and subsequent disappearance of Ag. tenuifolia, in the three millennia before the late 1980s. The loss of Ac. cervicornis to disease, its replacement by Ag. tenuifolia, and the loss of Agaricia to bleaching a decade later were novel events on a timescale of millennia, and they occurred following an extended period of stable sea level (a sea-level rise of about 1 m in the past 3,000 yr). There is growing concern that global climate change is degrading coral reef ecosystems, with coral mortality increasing as a result of bleaching and emergent diseases: our results from Belize appear to justify this concern. Richard B. Aronson*, William F. Precht†, Ian G. Macintyre‡, Thaddeus J. T. Murdoch* *Dauphin Island Sea Lab, 101 Bienville Boulevard, Dauphin Island, Alabama 36528, USA e-mail: [email protected] †PBS&J, 2001 Northwest 107th Avenue, Miami, Florida 33172, USA ‡Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington DC 20560, USA