A century-old collection of Antarctic sea urchins is being compared with modern samples to assess the impact of ocean acidification on marine life. The historical specimens were gathered by polar explorers including Captain Robert Falcon Scott, Sir Ernest Shackleton and Carsten Borchgrevink between 1898 and 1913.
Dr Hugh Carter, curator of marine invertebrates at the Natural History Museum, led a six-week research trip in January to revisit the exact sites sampled by those expeditions. His voyage, part of a multidisciplinary project run by New Zealand's National Institute of Water and Atmosphere (Niwa), retraced parts of Scott's route. The samples were collected about a month before Scott and his team perished in the ice.
Preliminary findings suggest that modern urchins have thinner, more fragile shells compared with their historical counterparts. Some modern specimens were crushed by the force of a hose used to clean them. Carter noted: 'All the ones we collected were fragile and some of them collapsed. From initial appearances, the modern specimens we collected have weaker tests than the historical ones.'
Ocean acidification, caused by carbon dioxide absorption, reduces calcium carbonate availability, making it harder for organisms like urchins, corals and oysters to build shells. In June, research showed 60% of global waters had breached the safe acidification limit. Carter warned: 'It could make the seas unliveable for things with a calcium skeleton.'
Despite the concerning findings, the expedition also recorded positive signs of biodiversity. Carter observed up to 150 whales and noted 'crazy levels' of wildlife on Coulman Island, including 17 starfish species in a 100-metre stretch. He said: 'It is a thrill to know that the environment is not as bad in some parts of the world as it could be.'
