A stream multimetric fish index in a large-sized city in south-eastern Brazil

Abstract

Aim Our study was carried out to develop a multimetric index suitable for urban wadeable streams in Sorocaba, a large-sized city from the Atlantic rainforest in south-eastern Brazil. Methods Twenty-seven stream stretches were selected for environmental and fish evaluation. Twenty ecological metrics were tested over an environmental gradient between the reference and degraded stretches. Candidate metrics were screened for range, responsiveness, and redundancy. We calculated a multimetric fish index (MFI) subdivided into five quality classes: reference ≥ 0.8, 0.6 ≤ good < 0.8, 0.4 ≤ moderate < 0.6, 0.2 ≤ poor < 0.4, and bad < 0.2. Results Four metrics were adequate for discriminating higher biotic quality from degraded stretches. Five stream stretches (18%) were classified as a reference or good, and 16 (60%) were poor or bad. Three reference stretches could be used for a hydromorphological restoration programme. Conclusion Our results indicated that biological integrity was altered, which was indicative of severe environmental degradation. Our study results may be useful for a management and restoration project of the Sorocaba/Médio Tietê hydrographic basin.

A review of the application of the Macroinvertebrate-based Multimetric Index (MMI) for water quality monitoring in lakes

“…The nal selection of metrics for an MMI is expected to be the most robust multimetric understanding of biological conditions (Hering et al 2014;de Carvalho et al 2017). MMI can be calculated as the mean of 0-1-digit ratings for all core metrics if the same number of metrics have been chosen for each metric category (Hering et al 2006;Silva and Cetra 2021). Weighting factors can be used to make sure that each group of metrics clustered inside a type has the same impact on the nal Multimetric Index if the quantity of core metrics belonging to various metric types uctuates (Hering et al 2014).…”