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(W/EH124) Effects of 2,4-dichloroaniline exposure on various blood parameters in rainbow trout. Kilemade, Michael1, Fitzgerald, Richard2, Rose, Tina2, Teurtrie, Gwenola1, Mothersill, Carmel1, 1 2 ABSTRACT- Blood physiology and biochemistry can be considered as essential indices to the general health status of fish. It has been illustrated that the use of haematological variables as indicators of stress and toxic substances can provide information on the physiological response fish make to a changing external environment. 2,4-dichloroaniline (2,4-DCA) has been detected in river water samples and is known to be toxic to fish and mammals. However, scarce data exists on the toxicological effects of this chemical. In this study, the effect on a variety of haematological and non-specific defence parameters was examined in rainbow trout, Oncorhynchus mykiss exposed to 2 and 10microMolar (2,4-DCA) for 6 and 13 days in an aerated, dechlorinated, exposure system. Pathologically, the fish displayed typical responses to aniline exposure. These included, pale gills, enlargement of the liver and spleen with general darkening and necrosis. Several fish also demonstrated advanced jaundice. Most importantly however was the detection of severe anaemia. Anilines such as 2,4-DCA are well documented with regards to their ability to cause anaemia and related problems in a wide range of organisms. In this study, fish were killed and blood samples for haematological and biochemical analyses were taken via caudal vessels. Haematological findings included a decrease in erythrocytes and a corresponding elevated incidence of disintegrated erythrocytes particularly at the higher concentration. Haematocrit values were found to be extremely low at the higher exposure. The relative proportions of erythrocytes to leucocytes were also found to decrease upon exposure to 2,4-DCA. The haematological results indicated that the fish were suffering from a haemolytic anaemia. In terms of blood biochemistry, serum lysozyme activity appeared to be the parameter most adversely affected by 2,4-DCA with significant reductions in activity upon exposure. No significant differences were found between the controls and the treatments in terms of serum protein and the total iron content of the serum. Key words: rainbow trout, haematological variables, 2,4-DCA, stress indicators |
