engleski

Index of biotic integrity of the fish community in large Croatian rivers

The Index of Biotic Integrity (IBI) is a method for using the referent values approach in order to quantify the impacts of human activities on aquatic ecosystems using fish communities, as first described by Karr (1981). The IBI includes a group of parameters based on the composition of the community and function by calculating the index at the sampling site and later comparing the index with expected values at similar habitats without the impacts of stress. The IBI was conceived in North America and attempts have long been in place to standardize the method for application in Europe. This work presents the first efforts in Croatia to determine referent values in the large rivers of the Danube Basin: Sava, Drava and Danube, in which fish communities were compared at 14 study sites. In order to determine the referential values, we examined 73 fish collections with a total of 23, 847 individuals. The IBI was calculated in comparison with the referent values at the study sites. The IBI ranged from 26 to 46 (of the total possible 60), which characterises poor to moderate water quality. We attempted to measure the European Fish Index (EFI ; Fame 2004) at the same stations ; water quality values corresponded with the IBI values at 5 of 14 stations. The database used by the EFI for comparison as a reference does not contain similar habitats, and these differences in index values were expected.

index of biotic integrity; large rivers; Croatia

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