Comparative analysis of a benthic macroinvertebrate-based biotic index: Evaluating the suitability of European BMWP versions and Tr-BMWP for Turkish river ecosystems

Biotic indices like the Biological Monitoring Working Party (BMWP) are widely used for freshwater quality assessment based on benthic macroinvertebrates. Many European countries have adapted BMWP to their local conditions, resulting in various regional versions. In Türkiye, the Turkish-BMWP was developed for national water quality monitoring, but the compatibility of other BMWP versions with it remains uncertain. This study assessed the applicability of different European BMWP versions in Turkish freshwater ecosystems. Benthic macroinvertebrate samples were collected from five ecologically different river basins in Türkiye. Families such as Baetidae, Heptagenidae, Ephemerellidae, Caenidae, Perlidae, and Hydropsychidae were identified in all basins. These families belong to Ephemeroptera, Plecoptera, and Trichoptera, collectively known as EPT, and these orders are frequently used as water quality indicators. The data were analyzed using the original BMWP and six adapted versions: Greek-BMWP, Iberian-BMWP, Czech-BMWP, Hungarian-BMWP, Polish-BMWP, and Turkish-BMWP. Compatibility with Turkish-BMWP was evaluated using Bland-Altman analysis and Spearman correlation. The results showed that Greek-BMWP, Iberian-BMWP, and the original BMWP had the highest agreement with Turkish-BMWP, making them more suitable for Turkish river systems. This study highlighted the importance of regional adaptations of biotic indices, as variations in benthic macroinvertebrate communities, environmental conditions, and pollution tolerance levels can affect their effectiveness. While multiple BMWP versions have been used in Türkiye, Turkish-BMWP provided the most accurate ecological assessments. If alternatives are needed, Greek-BMWP, Iberian-BMWP, and original BMWP are recommended, respectively. Additionally, Bland-Altman analysis proved more reliable than correlation analysis in comparing BMWP versions. This research contributed to the refinement of bioassessment tools and emphasized the need for continuous validation of biotic indices to ensure their applicability across different regions. Future studies should focus on further calibrating Turkish-BMWP with extensive datasets across diverse freshwater ecosystems in Türkiye.