Japanese researchers say a diver has found a huge coral mound thought to be about 300 years old off the coast of Azuchi-Oshima Island near Hirado, off the coast of Nagasaki. Satoshi Nojima, an associate professor in Kyushu University's Amakusa Marine Biological Laboratory, said the Stylocoeniella guentheri coral mound is 3.8 meters long, 3 meters wide and 1.3 meters tall. Stylocoeniella guentheri coral is found around Japan, the Philippines and Taiwan. It grows less than 5 millimetres each year. The largest previously known specimen measured about 50 centimetres.
Coral reefs, like tree rings, are natural archives of climate change. But oceanic corals also provide a faithful account of how people make use of land through history, says Robert B. Dunbar of Stanford University. In a study published in the Feb. 22 issue of Geophysical Research Letters, Dunbar and his colleagues used coral samples from the Indian Ocean to create a 300-year record of soil erosion in Kenya, the longest land-use archive ever obtained in corals. A chemical analysis of the corals revealed that Kenya has been losing valuable topsoil since the early 1900s, when British settlers began farming the region.