HABITAT SUITABILITY MODELS FOR WEST BALKAN TROUT FOR THE ESTIMATION OF ENVIRONMENTAL FLOWS IN A MOUNTAIN RIVER OF GREECE

摘要

This research is embedded into the ECOFLOW Project which focuses on the assessment of ecologically acceptable flows in Greek rivers. In this study a physical habitat simulation scheme was applied, based on hydraulic modelling and habitat evaluation with habitat suitability models. Regarding the habitat suitability models (HSM) the Generalized Additive Models (GAM) and those based on fuzzy logic have received increasing attention by environmental flow (e-flow) practitioners. Standard hydraulic simulation and aquatic habitat modelling was based on data surveyed along cross-sectional transects in HEC-RAS and for the first time, regional habitat suitability models for adult West Balkan Trout (Salmo fariodes) were developed using a GAM and a Tagaki Sugeno Kang fuzzy model. Both models presented similar performance showing that the West Balkan Trout selects slow flow microhabitats with large depth and coarse substrate with abundant cover. A representative stretch of the mountainous part of Acheloos River was chosen for the physical habitat simulation; this stretch is located in relatively undisturbed conditions, upstream of the Mesochora dam. Interestingly, both HSM suggested enhanced habitat conditions after hypothetical water abstraction. Although this was not expected such phenomenon was ascribed to the specific geometry of the study site. This preliminary application highlights the need for further science-based approaches with regard to e-flow assessments based on hydrology and eco-hydraulics which are relevant to river ecology and current EU policy.