Use of statistical process control for coastal marine biological impact analysis

Abstract

Abstract Statistical process control, a procedure long practiced in industry, was assessed to determine its applicability as an ecological analysis technique. The procedure is easy to calculate, emphasizes visual display of data, facilitates analysis and comparison, and uses well tested zone rules to objectively identify out-of-control conditions. Statistical process control was applied to a marine database involving number of species, abundance and biomass of benthic invertebrates sampled over 13 years (July 1985 to April 1998). Two stations were evaluated representing reference and impact (i.e. test) conditions. Statistical process control revealed that some out-of-control conditions were naturally induced whereas others were probably related to anthropogenic activities. The procedure also effectively depicted seasonal fluctuations and long-term trends. Patterns and major trends identified using the technique corroborated those previously documented by analyses using more conventional approaches. While the procedure is well established as an industrial quality control protocol, it has the flexibility and latitude to be considered as a useful tool in evaluating biological impacts. Comments on management applications are included.