Revision of the biological monitoring working party score system: Evidence from the subtropical urban river in China

Abstract

Despite their socio-economic and ecological functions, urban rivers are among the most endangered and threatened ecosystems, especially in developing countries, where the impact of population growth, urbanization, etc., on urban river ecosystem is more pronounced. Reliable and affordable bioassessment tools are fundamental for managing and restoring urban river ecosystems. This study collected macroinvertebrates from a typical urban river of the Pearl River Delta region in the dry season (December 2021 to January 2022) and the wet season (May to June 2022). Family sensitivity values (FSVs) were revised based on local biotic and abiotic data, and then used to adapt the Biological Monitoring Working Party (BMWP) and Average Score per Taxon (ASPT) indices. The study employed Shapiro-Wilk normality test and linear regression model to analyze the fitting relationship between bio-indices and Water Quality Index (WQI), and compared their differences between using the origin FSVs and revised FSVs. The results indicated that the revised FSVs for urban rivers decreased. Furthermore, due to differences in macroinvertebrate taxa composition and water quality conditions between dry and wet seasons, the revised FSVs differed between the two seasons, and the lower FSV of the specific family were recommended, reflecting the lower limit of pollution tolerance. The adapted BMWP and ASPT indices provide more accurate water quality assessment results and are reliable indicators in urban rivers. Thus, the adapted macroinvertebrate indicator is a suitable bioassessment tool for subtropical urban rivers in this region, allowing the identification of priority areas for management and a recovery plan.