Evaulation of the Quality of an Aquatic Habitat on the Drietomica River

The ecological status of a river is influenced by many factors, of which the most important are fauna and flora; in this paper they are defined as a habitat. During the years 2004, 2005, 2006 and 2011, research on the hydroecological quality of a habitat was evaluated in the reference section of the Drietomica River. Drietomica is a typical representative river of the Slovak flysch area and is located in the region of the White Carpathians in the northwestern part of Slovakia. In this article the results of modeling a microhabitat by means of the Instream Flow Incremental Methodology (IFIM) are presented. For the one-dimensional modeling, the River Habitat Simulation System (RHABSIM) was used to analyse the interaction between a water flow, the morphology of a riverbed, and the biological components of the environment. The habitat ´s hydroecological quality was evaluated after detailed ichthyological, topographical and hydro-morphological surveys. The main step was assessing the biotic characteristics of the habitat through the suitability curves for the Brown trout (Salmo trutta m. fario). Suitability curves are a graphic representation of the main biotic and abiotic preferences of a microhabitat´s components. The suitability curves were derived for the depth, velocity, fish covers and degree of the shading. For evaluating the quality of the aquatic habitat, 19 fish covers were closely monitored and evaluated. The results of the Weighted Usable Area (WUA = f (Q)) were evaluated from a comprehensive assessment of the referenced reach of the Drietomica River.