Application of Extended Habitat Suitability Curves for Depth in Nitrica River

Abstract

This study assesses the impact of basic stream abiotic parameters on the quality of aquatic habitat and inserts them to the aquatic habitat quality assessment of the mountain and piedmont streams. The created methodology was applied on the Nitrica River. The study is based on the objectification and modification of parameters of habitat suitability curve for the depth. The habitat suitability curve is one of the many basic parts of the Instream Flow Incremental Methodology (IFIM). IFIM is the methodology where the quality of aquatic habitat is interpreted according to a bioindication. The bioindication is provided by ichthyofauna. For this study, the minnow (Phoxinus phoxinus) was chosen as a bioindicator. The main reason for selecting the minnow as a bioindicator was that there was a sufficient frequency during the ichthyologic survey on the studied river. The basic result from the field measurement is the habitat suitability curve for depth. This measured habitat suitability curve is not adequate to describe the aquatic habitat. The suitability curve derived from just one measurement does not take into account the fact that the increase in flow has not changed the quality of the habitat until the time when the fish starts to be flushed out of the environment. This is the reason why this scientific research was oriented on the modification of habitat suitability curve for a wider range of flow. The evaluation was done by the System of Environmental Flow Analysis (SEFA). SEFA is a new software that implements the substance of the IFIM. The modification of the habitat suitability curve is applied on the Nitrica River.