Benthic Macroinvertebrate Multimetric Index for River (BMIR): Development of a multimetric index based on benthic macroinvertebrates for rivers in Türkiye

Abstract

Stream types determined according to altitude, slope and alkalinity in six different hydrobiogeographic regions of Türkiye were taken as the basis of the study. In line with the European Water Framework Directive, a macroinvertebrate based multimetric method was tested for Turkish rivers as a potential assessment. In this study, benthic macroinvertebrate data (3502 samples obtained from 1925 stations with reference points) were used to create a multimetric index for all river types in the hydrobiogeographic regions of Türkiye. Nine (9) biological metrics were evaluated and index development criteria were chosen to capture meaningful results at the ecosystem, community and individual levels. The metric combinations were chosen to show the best distinction between areas with no or only very minor anthropogenic disturbances and stressed areas (with discrimination efficiency values). The multimetric index, which includes three different metrics from three different metric categories, distinguishes reference or slightly distorted areas from stressed areas with an efficiency close to 100%. Index values were divided at a five-scale system between one (High) and zero (Bad) for biological evaluation. Further testing and research can be done so that the index will provide a more useful result as a bioassessment tool for decision makers in hydrobiogeographic regions. Also, the index can provide a basis for methods by which river status is assessed based on stress factors.