Creative Associates of the University of Plymouth

The Ocean Organ

Dr Kate Crawfurd and Prof. Jason Hall-Spencer


The Ocean Organ is a visual representation of Ocean Acidification. This occurs because carbon dioxide from the atmosphere dissolves in the oceans forming a weak acid. As carbon dioxide levels rise so the pH of the ocean falls. This particularly affects sea creatures that create shells from calcium carbonate like sea urchins, coral, shellfish, and some plankton. Currently the ocean pH is around 8.1, before the industrial revolution it was stable at 8.2 for at least 2,000 years. It is expected to fall to 7.8 by the end of this century.

Red cabbage acts as a pH indicator dye because it contains a pigment called flavin which changes colour with acidity.