Coral reefs are diverse and productive biological communities and important natural resources in tropical areas. However, reefs in many parts of the world are currently being threatened with a wide variety of anthropogenic disturbances (Richmond, 1993). In the state of Hawai’i, coral reef resources are worth over $100 billion and are being degraded by overfishing, sediment runoff, nutrient pollution, and impacts from tourism (Clark and Gulko, 1999). On the island of Hawai’i, tourism along the west coast of the island is focused largely on nearshore activities, especially sunbathing, beachcombing, snorkeling and diving. In a typical year thousands of visitors swim, snorkel and dive over the reefs to observe corals, other invertebrates and colorful fishes. As the number of visitors has increased in recent years there has been an increasing concern about potential impacts to coral reef ecosystems. In particular, observations of swimmers, snorkelers and divers standing and sitting on the coral are common as are instances of divers fins' breaking coral. Increasing occurrences of both bleached and broken coral in areas frequently visited by divers raised concern by the Hawai'i Division of Aquatic Resources that prompted the initiation of this study.
The goal of this study was to estimate the extent of damage due to divers using the incidence of bleached and broken coral at a popular tourist site, Kealakekua Bay, in west Hawai'i. The study compared the incidence of bleached and broken coral in an area of high diver activity to those in an adjacent low diver activity area. This study thus assumes that the two study areas were similar prior to the beginning of the study and had similar natural rates of bleaching and coral damage during the study period. These assumptions were tested during the course of the study.