OCEAN OFFENSIVE: Coral chemistry

The oceans are good at capturing CO , but the greenhouse gas makes the water acid, impeding coral growth. Scientists will now employ chemical weapons against this acidification. They have successfully used an Australian island as their test site.

One Tree Island

is a coral island with three lagoons separated by shallow thresholds lined with corals. On one of the thresholds, the water from the biggest lagoon flows into a smaller lagoon.

At one end

of the 35m-wide threshold, the scientists slowly released 15,000 litres of very alkaline sodium hydroxide, NaOH, which neutralised extra CO in the ocean water.

The sodium hydroxide

reestablished the original acidity of the ocean, and the scientists observed that the corals that lived in neutral water grew 6-8% more rapidly.

THIRD LAGOON Shallow threshold FIRST LAGOON NaOH Shallow threshold Corals influenced by acid 35 M Corals in neutral water Corals influenced by acidification