Trakia Journal of Sciences, Vol. 14, № 1, 2016 1 Trakia Journal of Sciences, No 1, pp 1-15, 2016 Copyright © 2016 Trakia University Available online at: http://www.uni-sz.bg ISSN 1313-7050 (print) ISSN 1313-3551 (online) doi:10.15547/tjs.2016.01.001 Original Contribution MORPHOLOGICAL AND HEMATOLOGICAL PARAMETERS OF CARASSIUS GIBELIO (PISCES: GYPRINIDAE) IN CONDITIONS OF ANTHROPOGENIC POLLUTION IN SOUTHERN BULGARIA. USE OF HEMATOLOGICAL PARAMETERS AS BIOMARKERS Zh. Zhelev 1* , D. Mollova 1 , P. Boyadziev 2 1 Department of Human Anatomy and Physiology, Faculty of Biology, University of Plovdiv “Paisii Hilendarski”, Plovdiv, Bulgaria 2 Department of Zoology, Faculty of Biology, University of Plovdiv “Paisii Hilendarski”, Plovdiv, Bulgaria ABSTRACT Basic morphological and hematological parameters were studied in adult, sexually mature individuals of Carrasius gibelio living in two rivers with varying degrees and different types of anthropogenic pollution (less disrupted site, domestic sewage pollution and heavy metal pollution) in Southern Bulgaria. The study was conducted on 30 female fish, age 3+ from each site. The results show that in C. gibelio, which inhabit the site with heavy metal pollution, the morphological parameters BW and FCF have the lowest statistically significant values. Specimens of C. gibelio from the river site with domestic sewage pollution have the following hematological profiles: erythrocytosis, leukocytosis and hyperchromia, differential leukocyte count: neutrophilia, eosinophilia, monocytosis and lymphocytopenia. Red cell indices (MCH, MCHC and MCV) display the highest statistically significant values. The C. gibelio specimens from the site with heavy metal pollution had the following hematological profiles: erythrocytosis, leukocytopenia and hypоchromia, differential leukocyte count: neutrophilia, eosinophilia, monocytosis and lymphocytopenia. The lowest statistically significant values of red cell indices (MCH, MCHC and MCV) indicate anemic changes of microcytic and hypochromic type. The hematological parameters of C. gibelio are adequate biomarkers of the physiological state of animals and their habitats. Key words: Prussian carp, morphological parameters, hematological parameters, domestic sewage pollution, heavy metal pollution, environmental bioindicators. INTRODUCTION At the end of the last century, and the beginning of the present century, anthropogenic pollution of the environment turned out to be a global ecological problem which affects all countries. Human activities have negative effects on both marine and fresh water ecosystems. Fish are very sensitive to anthropogenic pollution and some of them have been widely used in toxicological studies as models to evaluate the health of aquatic ecosystems (1). Hematological parameters are widely used indicators of environmental stress in fish. A _________________________ *Correspondence to: Zhivko M. Zhelev, University of Plovdiv “Paisii Hilendarski”, Faculty of Biology, Department of Human Anatomy and Physiology, 24 Tsar Assen Str., 4000 Plovdiv, Bulgaria; e-mail: zhivko-m@uni-plovdiv.bg literature survey shows that most experiments studying the hematological parameters of several marine and fresh water fish have been conducted in labs under controlled conditions. The aim of these studies is to identify the changes in the values of various hematological parameters under the effect of different types of toxicants as well as under the effect of their different concentrations. The changes in the blood of various representatives of Teleostei fishes have been tested under the effects of toxic plant extracts (2), crude oil (3), pesticides (4), various heavy metals (5) or a combination of several heavy metals (6). There have been relatively few studies carried out in seas and rivers polluted by human activities (7-10), where xenobiotics mix with the characteristics of the environment. This mixture complicates the identification of the relations among the changes in the values of hematological parameters (in the physiology of fish