Ecological characteristics of the main river catchments in Vrachanska Planina Mountains

Abstract

Assessment of the ecological status of river ecosystems of the major watersheds in the Vrachanska Planina Mts. (Leva River, Cherna River and some tributaries) is made. The assessment is carried out by determining the composition and structure of phytobenthos, benthic macroinvertebrate communities and fish. The following indexes are calculated: diatom pollution index IPS, macrozoobenthic Biotic Index and Fish Based Index (BFI), adopted for assessing the ecological status as required by WFD (Directive 60/2000). Additionally, various physical and hydrochemical analyzes are performed. Based on our results the majority of the mountainous zones of the studied rivers is "good" or "high" ecological status. Deteriorated ecological conditions is observed downstream some villages: for Leva River below the village of Zgorigrad and for Cherna River nearby the village of Dolno Ozirovo. This is probably owing to contamination with organic matter from the human settlements in the area. An accident pollution (with a predominantly protein character) was found in the Cherna River near the Lupovaka area.

Keywords

• macrozoobenthos
• fish
• diatoms
• ecological status
• biotic indices
• Bulgaria