Chronicles of the Anthropocene: the Osborne Reef.

A reef (from the Spanish-Arabic word arrasíf, meaning "paved") is a structure, usually coral or rocky, found near the surface of the sea. By extension, reefs also refer to the communities of fish, algae and invertebrates that inhabit them. They represent one of the most valuable ecosystems on Earth, since their enormous biodiversity, in the case of coral reefs, is comparable to that of tropical forests. In addition, they provide environmental services that are not inconsiderable, such as providing food for millions of people, dissipating the energy of tropical storms and tsunamis, fixing atmospheric carbon dioxide and offering sites of incomparable beauty. In sum, the services of the world's reefs are worth an estimated $375 billion a year. Not bad, considering that they do not even represent 0.01% of the Earth's surface (NOAA, 2008). Artificial reefs, on the other hand, are structures submerged or built to achieve one or more of these services, usually the protection of coasts and beaches from erosion. The first ones may have been built by the Persian civilization in the Tigris River, two thousand years ago, to protect against pirate raids. Because they provide a stable habitat for marine life, they also provide an incentive for recreational fishing and the cultivation of species of commercial interest. Some artificial reefs in Japan, for example, have been dedicated to the cultivation of pearl-producing oysters. Others were built for purely tourist purposes, either to generate waves conducive to surfing (such as the Cables and Bagarra reefs in Australia) or to attract divers and snorkeling enthusiasts. Some of the latter were designed and built by artists, such as those found in the Underwater Art Museum, in the West Coast National Park of Isla Mujeres, Punta Cancun and Punta Nizuc, in the Mexican Caribbean. Thus, although they have been built for several centuries, artificial reefs are proof that the alteration of the environment that characterizes the Anthropocene (?the age of man?) extends from the underwater depths to outer space.