THE ASSESSMENT OF SENSITIVITY OF BIOTIC INDICES IN DETERMINING SYMPTOMS AND LEVELS OF DISTURBANCE USING MACROBENTHIC ASSEMBLAGE DATA

Abstract

Marine macrobenthic dynamics have been intensively studied in response to environmental disturbances, and a large number of techniques, including a variety of indices, have been proposed and developed for assessment. Structural and functional variability have been summarized through both univariate and multimetric indices as integrative indicators in environmental monitoring programs. In general, multimetric indices are considered to be sensitive, stable, and robust, thus offer a promising approach for ecological assessment. This study is aimed to assess the degree of sensitivity for several indices in terms of their ability to determine environmental changes. Based on macrofaunal data, several univariate and multimetric indices were used to assess and compare the level of disturbance at fallowed farm and reference (control) sites. The two multimetric indices, the AZTI’s Marine Biotic Indices (AMBI) and Ecological Quality Ratio (EQR), were used as integrative indicators to assess the categorisation of each sampled site. The results showed that a combination of multimetric index and univariate indices provide a better assessment. The categories determined by multimetric indices seem to be in accordance with level of disturbance expressed by the trophic analysis, multivariate and graphical analyses used in this study. The AMBI has the ability to detect large scale differences among sites. However, AMBI was unable to discriminate slight changes in the macrobenthic assemblages between sites, as have been exposed by EQR.