Ecological co-inhabitance index (ECI) as a management tool for ecosystem preservation in rivers

The number of novel man-made hazardous substances produced by industries is increasing year after year, resulting in conventional discharge standards ineffective to preserve the natural ecological environment. A novel index, ecological co-inhabitance index (ECI), was proposed in order to evaluate th e river ecosystem sensitively. The river benthic community with a high valu e of ECI is formed in the healthy ecosystem where benthic animals can share resources in the river environment efficiently, keep the ecosystem functio ning, and give the least adverse effect to lower reaches of the river. In o rder to clarify the characteristic of ECI, the relationship between ECI and water quality in the river was investigated using the data on benthic anim als obtained from 17 various rivers. Results of this investigation indicate d that ECI could synthetically evaluate the river environment without a bia s toward a specific water quality. Moreover, ECI had the significant correl ation coefficients with diversity index, biotic index and pollution index a t significance level 0.05, respectively. Therefore, ECI is a promising inde x for managing the river ecosystem.