RESEARCH REGARDING THE FISH COMMUNITIES IN BAHNA, TOPOLNITA, AND BLAHNITA (DANUBE TRIBUTARIES, ROMANIA)
DOREL URECHE, CAMELIA URECHE "Vasile Alecsandri" University of Bacau, Faculty of Sciences, Department of Biology, Ecology and Environmental Protection, 157 Marasesti Street, 600115 Bacau, Romania, e-mail: dureche@ub.ro, urechec@ub.ro
The study was carried out in three of the Danube tributaries in 2007. The aim of the study was to assess the state of fish communities in this area, and also to highlight significant aspects regarding the fish communities, such as biodiversity, stocks, and biological integrity. The biological material was sampled by electrofishing from 10 sampling sites. The biodiversity is quite high, during the study period, 37 fish species being identified, with an amount of 2722 individuals and 35716.6 g. Only one of the 37 fish species is non-native (Pseudorasbora parva) while the rest of 36 fish species are native. The species frequency ranges between 90% and 10%. The chub has recorded the highest value of the frequency (90%) and it is followed by the Mediterranean barbell (60%) and then by bleak and Rhodeus amarus (50%). We found that the numerical stock in sampling sites ranged between 0.19 and 178.67 ind./100 m2, the highest value being recorded by the Mediterranean barbell, while the weight stock ranged between 0.46 and 2012.89 g/100 m2, the highest value being recorded by the chub.
