The purpose of this study is to evaluate the benthic macroinvertebrate distribution in the Keşap Stream
(in the Eastern Black Sea Region of Turkey) for the summer period using biotic index. The water quality was assessed
through the application of the Belgian biotic index. For this purpose, benthic macroinvertebrate sampling was performed
in six sites along the Keşap Stream in the summer period, in July 2007. The distribution of dominant genera of the sites
was evaluated according to water quality. According to the Belgian biotic index, II, III and IV water quality classes
(slightly, moderately and heavily polluted, respectively) were determined in the stream. In addition, diversities of
benthic macroinvertebrates in six sites were calculated. The biotic index values are found also consistent with the
diversity values. Especially, in areas of the stream after industrial facilities water quality decreased. However, very
heavy pollution was not observed accord to the biotic index values. It was found that Ephemeroptera was the dominant
major taxon in all sampling sites. As a result of this biological evaluation, Ephemeroptera were concluded to be the most
common taxa in the stream and the ephemeropterans,
Potamanthus
,
Baetis
and
Ephemerella
were dominant genera in the
conditions of slightly, moderately and heavily polluted.
