A species of cold-water coral keeps an accurate record of marine phosphorus concentrations, report geoscientists.
A species of cold-water coral keeps an accurate record of marine phosphorus concentrations, report geoscientists. The coral Desmophyllum dianthus incorporates phosphorus into its skeleton at concentrations proportional to those in the surrounding ocean.
Phosphorus is an essential nutrient for animals and plants, but tends to be less abundant than other nutrients. Phosphorus is often the main limiting factor for plant growth, on land and at sea.
A record of environmental phosphorus concentration reflects past biological productivity: high concentrations indicate high levels of productivity.
Scientists have had no way of directly measuring historical phosphorus concentrations in the ocean. Estimates of phosphorus concentrations were based on measurements of other nutrients, such as carbon and cadmium, in the shells of single-celled marine organisms called foraminiferans.
The researchers from Italy, Spain and Australia wondered whether a direct record of phosphorus concentrations might be found in coral tissue and investigated D. dianthus, which is found all over the world.
Using a mass spectrometer, they measured phosphorus concentrations in samples of the coral taken from the Mediterranean Sea, the Pacific Ocean near Australia and off the Chilean coast. They compared these with direct water measurements of dissolved inorganic phosphorus and found that they matched.
They also discovered that 30-year old coral from the Mediterranean contained a record of phosphorus concentrations that matched water measurements taken over the same length of time. Fossilised coral samples contained a record of phosphorus concentrations stretching back over 10 000 years.
It’s a ’great’ discovery, said Adina Paytan, an expert in chemical oceanography at Stanford University, California. ’The next step should be to conduct research that will increase our understanding of the mechanisms of phosphorus incorporation and preservation in the corals,’ Paytan told Chemistry World. ’This information is fundamental to any application of this potentially exciting new tool.’