Assessment of fish communities from biotic type 6 in Black Sea Basin in Bosnia and Herzegovina

Abstract

Fish are very sensitive to changes in damming of rivers, fragmentation and destruction of habitats, and changes in physical and chemical parameters. Changes in species diversity are a signal indicating that a significant and, as a rule, long-term change in one or more factors has occurred in the aquatic ecosystem. This in long term could lead to reduction of diversity and significant changes in the structure and dynamics of aquatic ecosystems. Biomonitoring of ichthyofauna is a very important element in the ecological assessment of water quality since changes in the structure of the fish community reflect changes in the quality of water in freshwater systems. The grouping of fish into ecological guilds has greatly improved our understanding of the impact of anthropogenic activities on fish and their communities. Therefore, the fish guilds represent the basis for ecological assessment based on the preferences of each recorded species in relation to tolerance, habitats, nutrition, reproduction and migrations. The results of the analyses of the structure of fish communities at 166 sites in biotic type 6 in the waters from the Black Sea Basin in Bosnia and Herzegovina have shown that the greatest influence on the distribution of different fish species has water temperature, flow, dissolved oxygen, and pH value. Obtained results clearly indicate an inverse relationship between altitude and the level of fish biodiversity. Values of applied diversity indices stress that fish communities in a river system usually follow a pattern of increasing species richness and diversity from upstream to downstream.