Search

The objective of the study was to evaluate stress invoked by a temperature decrease in the common carp (n = 56). After acclimatisation to laboratory conditions at a temperature of 27.8 ± 1.0 °C, the fish (n = 28) were transferred to 16.8 ± 1.0 °C water (group T2; temperature difference -11 °C); the rest of the fish were kept at the original water temperature (group T1). The examination of individual fish was made after 6, 12, 24 and 48 hours (h). The impact on the haematological and biochemical indices was evaluated. Furthermore, the effect on the food content passage speed was investigated and a histopathological examination was performed. The changed haematological indices in the T2 group returned to the T1 values 48 h after a temperature decrease, except for the neutrophillymphocyte ratio which was found to be higher in all the T2 samplings. Most of the monitored biochemical indices decreased in the T2 group and some of them remained that way at 48 hours. On the contrary, the liver enzymes increased in the T2 group at 48 hours. The passage of food through the digestive tract was mostly finished after 48 h for both groups. However, in the warmer water, the intestine was empty in 71.4% cases after 24 h already, while in the T2 group, the food content passage was only completed in 14.3% of the fish at the same time. Local gill and skin necrosis, and mononuclear cell infiltration were found in the T2 group. A sudden change in the temperature can affect various parameters of the common carp, however, these changes can mostly be eliminated within 48 hours. [ABSTRACT FROM AUTHOR]

• Chronic atrazine exposure causes abnormal behaviour and reduction in feed intake. • Chronic atrazine exposure causes oxidative stress and disturbs metabolic pathway. • Chronic atrazine exposure results in morphological changes in the gill. • Atrazine decreases carp resistance against parasite infection. Atrazine is frequently detected in surface waters and negatively affect physiological function in aquatic organisms. Even though numerous authors have intensively studied its toxicity, only limited information concerning the long-term fish exposure is available. The aim of this study was evaluation of chronic exposure in common carp. Fish were exposed to a range of atrazine concentrations (0.3 – environmentally relevant concentration; 300; 1000; and 3000 µg/l) for twelve weeks. The potential impact of atrazine exposure was studied using various markers (behaviour; biometrical characteristics; haematological, biochemical and oxidative stress indices and histopathological changes). Most alterations were recorded at the highest concentration (3000 µg/l) which is probably due to a combined effect of both the herbicide exposure and intensive parasite infection development during second week. This group was cancelled after three weeks due to adverse health status, which partly confirmed atrazine immunotoxicity. Chronic exposure resulted in long-term reduction in feed intake followed by a significant decrease in body weight and morphological changes in gill at 1000 µg/l. At the same concentration, significant alterations in haematological (e.g. increase in erythrocyte, leukocyte, lymphocytes and neutrophil counts as well as decrease in monocyte counts) and biochemical (e.g. changes in enzyme activities; increase in glucose; decrease in ammonia) indices were documented, especially during first three weeks. Similar trend, but not so intensive, was observed at 300 µg/l. Moreover, significant changes were observed in various indicators of oxidative stress. These alterations were highly variable with both increasing and decreasing trends depending on dose and analysed tissue. Significant changes, especially in white blood profile, enzyme activities and oxidative stress indices, were proven even at 0.3 µg/l. Obtained results indicate that chronic atrazine exposure of common carp can negatively influence many indicators of health status such as behaviour, immune response, haematological and biochemical profile, oxidative stress indices and organ histopathology. [ABSTRACT FROM AUTHOR]