Effects of an MCPA-based herbicide formulation on the common carp Cyprinus carpio Linnaeus, 1758 – haematological, biochemical and histological evaluation

Herbicides (weed control agents) are used in crops on a massive scale. MCPA (2-methyl-4-chlorophen- oxyacetic acid) is a herbicide used to control weeds in cereals and other crops. The aim of this study was to investigate the toxic effects of an MCPA-based herbicide formulation (Chwastox Extra ® 300 SL) in the common carp ( Cyprinus carpio ). The fish were exposed for 10 days, to a concentration which corresponded to 1 mg/l or 5 mg/l of MCPA. Our analysis showed fluctuations of the haematological parameters during the treatment. Plasma biochemical changes that were statistically significant, i.e.a decrease of the total protein concentration and alanine aminotransferase activity, were observed after 1 day of exposure. No histopathological lesions in the gills, trunk kidney and liver were identified. The results of the present study indicate that Chwastox Extra ® 300 SL has a relatively low toxicity for the common carp. It was also observed that the blood indices were more sensitive to the tested herbicide formulation than the microstructure of the selected organs. Further research aimed at studying the effects of Chwastox on water invertebrates and fish of other taxa is recommended.