Intercalibration Procedure of the Framework Directive on Water - Comparison of Results for Macrozoobenthos on the Example of Reservoir Lakes of the Drava River in Medumurje, Croatia

Abstract

The Water Area Management Plan 2016-2021 assessed reservoirs as natural water bodies. This assessment included their ecological condition. The goal of the intercalibration procedure is to achieve consistency, comparability of results and evaluation of the ecological state based on the biological element of macrozoobenthos quality. The paper presents the results of research on the Cakovec HPP and Dubrava HPP reservoirs on the Drava River from 1999 and 2003. Complex studies of individual biological elements of macrozoobenthos included seasonal monitoring. They are part of the overall state of the cenosis and water quality with the aim of determining trophic characteristics and water quality by monitoring the quantitative and qualitative composition of the population of macrozoobenthos.The research obtained the values of the abundance of individual taxa of bottom macrofauna by reservoir stations, the total number of individuals, the number of indicator individuals, the saprobic index (SI), the number of taxa and the number of indicator taxa. The author compared the obtained results with the old and new Regulations on water quality standards in the prescribed indices and limit values of the macrozoobenthos biological element. The obtained results show the bad ecological condition of the reservoirs (as well as the ecological potential). In 2021, this area officially became part of the Five-State Biosphere Reserve.