Deep-sea corals feel the flow

Shallow-water corals provide the only direct way of determining the absolute timing and magnitude of sea levels over the past 600,000 years. Their uranium and thorium abundances and uranium isotope ratios, combined with coral-reef elevations, help to determine past sea levels (1). The veracity of the dating results depends on the state of preservation of fossil corals over extended time periods. Models have been developed to correct for specific complications. Deep-sea corals (see the photo) do not provide sea-level information. However, as Chen et al. (2) show on page 626 of this issue, they appear to be responsive to ocean circulation changes and continental riverine and ice-sheet meltwater inputs to the oceans. In addition, the data help to resolve one of the most contentious issues in uranium series dating, namely whether systematic variations in 234U are due to physical ocean processes or are artifacts of poor preservation.