Flow predictability indicates the ecological quality of the river: A case of invertebrates in Central Europe

Flow regime and its variability play a fundamental role in preserving rivers' ecosystems. Effects of flow predictability modeling on macroinvertebrate community structure parameters and taxonomic composition were investigated. The main aim of the present work was to apply flow predictability as an indicator of river ecological health and to investigate the relationship between the flow predictability index and macroinvertebrate assemblages variation. Due to the high spatial variability in the abiotic and biotic characteristics of rivers, the classification and regression trees algorithm in respect to Polish Biological Monitoring Working Party (BMWP_PL) index on regional scale was done. The study was conducted in 30 catchments representing various rivers (from 0 m a.s.l. at the Baltic Sea, up to 2500 m a.s.l. in the Tatra Mountains) of Central Europe. Principal component analysis of macroinvertebrate habitat metrics indicated the presence of two groups of habitat characteristics. One of them is related to the quantitative characteristics of the regime, whereas is the second with the seasonality-predictability of the regime. Redundancy analysis showed that predictability of the hydrological regime was the most influential variables on macroinvertebrate community parameters. Generalized linear modeling showed that predictability (positively) and watershed area (negatively) influence on BMWP_PL index referred to the ecological statement of the river. Based on the main components analysis and CART algorithm in terms of the BMWP_PL index, analyzed catchments were divided into five groups according to predictability, high pulse durations, and catchments area. The predictability index is proposed as a good method for estimating the impact of human pressure on river biota without performing an extensive hydrobiological survey.