Coral reefs, home to the moray eel.

By Aimée Komugabe

If you’ve watched Finding Nemo and Shark Tale you’d have an idea why coral reefs are popularly known as “rainforests of the sea”. These corals support a complex habitat structure of over one million species – from microscopic dinoflagellates to sea snakes to cetaceans (e.g. dolphins) that visit from time to time. Corals are one of the longest-lived marine creatures and can build carbonate mounds up to 300m high! We just have to look in our own back yard – the Great Barrier Reef. These corals are not only home to Nemo, Dory and a whole host of other organisms, but they also give us clues on environmental changes in the ocean.

Marine scientists here at RSES and elsewhere in the world have been able to show that certain trace elements in the coral carbonate skeletons reflect ambient environmental conditions. Different elements in the ocean are controlled by different variables giving rise to different “proxies”.  A proxy is a measurement or physical quantity that is used as an indicator of another. For example, uranium and strontium incorporation into the coral skeleton is temperature dependent, and thus they have been used successfully as proxies for sea surface temperature (SST).

Just last month, a paper by one of our very own researchers at RSES was published in Paleoceanography showing how we can now get more accurate changes in SSTs from corals by factoring in skeletal growth rates and mass accumulation into calibration models. This is a pretty neat thing, and corals are truly proving to be reliable long-term recorders of climate change.