STATE OF CORAL-REEFS IN THE GALAPAGOS-ISLAND - NATURAL VS ANTHROPOGENIC IMPACTS

Before the 1982-1983 El Nino disturbance event low diversity coral communities and small, actively accreting coral reefs were present on Galapagos shallow shelves in areas protected from strong upwelling. Prolonged El Nino 1982-1983 sea warming resulted in 95-99% coral mortality, virtually eliminating corals throughout the archipelago. The population size of an ubiquitous, large sea urchin species (Eucidaris thouarsii) was unaffected by the warming event. Urchins later showed increased abundance on dead coral colonies and frameworks, and caused bioerosion that exceeded the net calcification capacity of disturbed reefs. Known human impacts on corals result mainly from anchor damage, the collection of corals for sale as curios, and mechanical damage resulting from the activities of fishermen. An evaluation of natural and anthropogenic damage to Galapagos coral communities indicates that natural disturbances, especially strong ENSO episodes, are of greatest concern. However, rapidly increasing human pressures could exacerbate the recovery capacity of naturally perturbed coral communities.