Coral keeps nutrient record

For a record of seawater phosphorus levels, look no further than the deepwater coral Desmophyllum dianthus (shown). Phosphorus uptake plays a key role in the ocean's biological productivity. Researchers from Italy, Australia, and Spain have found that D. dianthus, a coral with a skeleton of the form of calcium carbonate called aragonite, incorporates phosphorus into its CaCO₃ crystalline lattice in ratios linearly proportionate to the amount of dissolved inorganic phosphorus in seawater (Science 2006, 312, 1788). By tracing phosphorus levels in coral, scientists may be able to track atmospheric carbon dioxide levels, too. Phosphate levels in the ocean limit marine biological productivity, which indirectly modulates atmospheric CO₂ levels. Information from fossil and living corals can reveal historical levels of atmospheric CO₂ and offer insight into the ocean's ability to buffer future increases, the authors suggest.