COMPARISON OF THE HISTOLOGICAL CHANGES IN ORGANS OF CHUB (Leuciscus cephalus) WITH THE NUMBER OF BACTERIA IN THE WATER OF SAVA RIVER

Abstract

In this study we sampled 157 chubs on 5 sites from slovenian–croatian border through to the inflow of river Una in Sava. Two sites were upstream while the remaining were downstream from the city of Zagreb. Gills, intestine, spleen, kidney and liver were sampled from all fish. Histological slides were stained with haematoxylin and eosin and examined under the light microscope. At the same time, water was sampled for the counting of coliforms and heterotrophic bacteria. According to the results of this study we can conclude that fish histology is a valuable indicator of water pollution. The intensity of histological parameters was in correlation with the number of bacteria in water. Furthermore, fish histology proved to be more reliable method than water microbiology as differences between two sampling seasons were not significant for histological indices while being significant for bacteria counts. At least one histological parameter highly correlated with water quality was found in every organ. Of the organs examined, response in the gills correlated best with changes in water quality.

Keywords

• histology
• chub
• coliforms
• heterotrophic bacteria
• water quality