Quantifying the condition of Hawaiian coral reefs

(1) This investigation developed and tested descriptive models designed to evaluate coral reef ecological condition based on data developed using the basic techniques most often used in coral reef surveys. (2) Forty-three variables at 184 stations were analysed in order to identify specific factors that are useful metrics for describing reef condition. (3) The common practice of using ‘reference sites’ for paired site comparisons was evaluated by developing a reference site model (RSM). This use of reference sites proved to be subjective and unreliable, especially when multiple factors and multiple sites are involved. However, in some cases the RSM is appropriate in demonstrating severe degradation based on factors such as sediment, coral cover and fish abundance. (4) An objective ecological gradient model (EGM) was developed based on a wide range of metrics at numerous sites. A computer program was developed that allows a quantitative ranking of reef condition along a continuum and can be used to compare reefs across a wide range of conditions. Further, this approach permits the operator to alter and define criteria appropriate to a specific question. (5) Results of this investigation provide ecological insights into the importance of natural and anthropogenic ecological factors in determining coral reef condition. Copyright r 2009 John Wiley & Sons, Ltd. Received 3 October 2008; Revised 18 February 2009; Accepted 22 March 2009