An Analysis of the Biological and Physical Relationships in the Coral Reefs of Menjangan Island: Effect of Decling Coral Cover on Ecological Complexity
Lehman, Amber Pearl
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Reef rugosity, the standard index of coral reef physical complexity, has classically been determined as the ratio between a taught rope and a chain draped onto the substrate of a reef. A new method of measuring reef rugosity, termed Digital Reef Rugosity has recently been pioneered by Phillip Dustan. It is believed, as is true with other biological communities, that increased habitat complexity in a coral population will lead to an increased fish species diversity. The Biosphere Foundation carried out a four month expedition to Bali, Indonesia to access the vitality of Menjangan Island's coral reefs. We found that Balinese coral reefs with greater structural complexity (rugosity) contain more fish most probably due to increased niche diversity. Additionally, reefs with more diverse coral communities also tend to have greater fish species diversity. Thus both physical and biological complexity are significant components of coral reef ecological integrity. However, the correlation between coral and fish biodiversity degrades as a function of decreasing coral cover. Weakening coral and fish diversity relationships with decreasing coral cover may indicate a “tipping point” where the coral reef communitiy begins to collapse.