Modelling macroinvertebrate and fish biotic indices: From reaches to entire river networks

• Published in: The Science of the total environment Vol. 577; pp. 308 - 318
• Main Authors: Alvarez-Cabria, Mario, Gonzalez-Ferreras, Alexia M, Penas, Francisco J, Barquin, Jose
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.01.2017
• Subjects: Animals; Cantabrian region; Ebro River; Ecosystem; Environmental Monitoring; EPT; Fishes; Freshwater; IASPT; Invertebrates; Life; Models, Biological; Rivers; Salmonid biomass; Salmonidae; Spain; MED; ANE, Spain; EPT; Life; Ebro River; IASPT; Salmonid biomass; Cantabrian region
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2016.10.186

We modelled three macroinvertebrate (IASPT, EPT number of families and LIFE) and one fish (percentage of salmonid biomass) biotic indices to river networks draining a large region (110,000km2) placed in Northern and Eastern Spain. Models were developed using Random Forest and 26 predictor variables (19 predictors to model macroinvertebrate indices and 22 predictors to model the fish index). Predictor variables were related with different environmental characteristics (water quality, physical habitat characteristics, hydrology, topography, geology and human pressures). The importance and effect of predictors on the 4 biotic indices was evaluated with the IncNodePurity index and partial dependence plots, respectively. Results indicated that the spatial variability of macroinvertebrate and fish indices were mostly dependent on the same environmental variables. They decreased in river reaches affected by high mean annual nitrate concentration (>4mg/l) and temperature (>12°C), with low flow water velocity (<0.4m/s) and aquatic plant communities being dominated by macrophytes. These indices were higher in the Atlantic region than in the Mediterranean. This study provides a continuous image of river biological communities used as indicators, which turns very useful to identify the main sources of change in the ecological status of water bodies and assist both, the integrated catchment management and the identification of river reaches for recovery. [Display omitted] •Invertebrate and fish indices were predicted across whole river networks (110,000km2).•Models were done with the Random Forest analysis using 25 predictor variables.•Invertebrate and fish metrics showed similar spatial patterns.•All indices were mainly driven by the same environmental factors.•Indices were higher in the Atlantic region than in the Mediterranean one.