Physiological performance of common carp (Cyprinus carpio, L., 1758) exposed to a sublethal copper/zinc/cadmium mixture.

In a natural ecosystem, fish are subjected to a multitude of variable environmental factors. It is important to analyze the impact of combined factors to obtain a realistic understanding of the mixed stress occurring in nature. In this study, the physiological performance of juvenile common carp (Cyprinus carpio) exposed for one week to an environmentally relevant metal mixture (4.8 µg/L of copper; 2.9 µg/L of cadmium and 206.8 µg/L of zinc) and to two temperatures (10 °C and 20 °C), were evaluated. After 1, 3 and 7 days, standard (SMR) and maximum metabolic rate (MMR) were measured and aerobic scope (AS) was calculated. In addition, hematocrit, muscle lactate, histology of the gills and metal accumulation in gills were measured. While SMR, MMR and AS were elevated at the higher temperature, the metal mixture did not have a strong effect on these parameters. At 20 °C, SMR transiently increased, but no significant changes were observed for MMR and AS. During metal exposure, hematocrit levels were elevated in the 20 °C group. The bioaccumulation of Cd in the gills reflected the increased metabolic rate at the higher temperature, with more accumulation at 20 °C than at 10 °C. Anaerobic metabolism was not increased, which corresponds with the lack of significant histopathological damage in the gill tissue. These results show that common carp handled these metal exposures well, although increased temperature led to higher Cd accumulation and necessitated increased hematocrit levels to maintain aerobic performance.

Gill reaction to pollutants from the Tamis River in three freshwater fish species, Esox lucius L. 1758, Sander lucioperca (L. 1758) and Silurus glanis L. 1758: a comparative study.

The study evaluated the effects of waterborne pollutants from the Tamis River on gill histology and possible differences in gill reaction patterns between three freshwater fish species, pike Esox lucius L. 1758, pike-perch Sander lucioperca (L. 1758) and wels catfish Silurus glanis L. 1758 from the Tamis River. Gills from analysed fish species showed moderate to intense histopathological alterations. The most frequent progressive alteration was hyperplasia of epithelium, whereas the most frequent regressive alteration was epithelial lifting. Circulatory disturbances were most often manifested in the form of hyperaemia. During comparative analysis, differences in gill indices, reaction and alteration indices, as well as in gill and filament prevalence between analysed species, were observed. Although all analysed fish species did show both progressive and regressive alterations, there was a significant difference in the level of expression of these reaction patterns. Gill index obtained for pike clearly stands out as the lowest. Wels catfish showed the highest progressive reaction index, significantly higher in comparison with the other two species (P < 0.05), while pike-perch showed the highest regressive reaction index, also significantly higher in comparison with the other species (P < 0.001). These results may implicate species-specific gill reactions and thus present a useful tool for better understanding toxic mechanisms of various pollutants.

Effects of trifluralin on carp: biochemical and histological evaluation.

Acute and subacute toxicity of the herbicide trifluralin on fish was investigated in laboratory toxicity tests with carp. Median lethal concentrations were determined in acute tests. The 96-h LC50 value was 0.045 (0.036-0.051)mg/L. Fish were exposed to subacute concentrations of the herbicide (0.005, 0.01, and 0.02 mg/L trifluralin) in the 14-day toxicity tests and the effects on the relative growth rate, some biochemical parameters [alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanin aminotransferase (ALT) activities in serum, gills, liver, and kidney], gills, liver, and kidney structure were studied. A decrease in relative growth rate was found. An increase of functional enzyme activities in blood serum and the organs examined, particularly in the highest concentration of trifluralin indicated changes in the vital organs, was confirmed by histological analysis. The most severe changes (although mostly reversible) were found in the gills and kidney of the fish examined.

Functional enzymes activity and gill histology of carp after copper sulfate exposure and recovery.

Copper sulfate is one of the most widely used algicides for the control of phytoplankton in lakes, reservoirs, and ponds. It is also used for aquatic weed control. To study the toxic effects of copper on carp (Cyprinus carpio L.), toxicity tests were carried out. Fish recovery in copper-free water was followed. After a 14-day period of exposure to five concentrations of copper sulfate (0.25-4.0 mg/L CuSO4, values ranging from approximately 5 to 70% of the 96-h LC-50) and a recovery period of the same duration, activities of the functional enzymes alkaline phosphatase (AP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) in the blood serum and gills were determined. Because the gills are the known target organ for copper, changes in gill structure were investigated as well. In all exposure groups for all the enzymes studied, an increase in activity was noted after 14 days. The increase in AP activity was the most pronounced in both gills and serum of carp exposed to the highest concentration tested (4 mg/L). After a "recovery" period, compared with the end of treatment, a decrease in enzyme activities was recorded, indicating eventual recovery from the Cu-induced stress (the only exception being the ALT activity in gills in the highest CuSO4 concentration). The results of biochemical analysis were confirmed by histopathology. Lesions such as epithelial hyperplasia, curling of secondary lamellae, and changes in chloride cells were observed on the gills, and their severity increased with increased toxicant concentration. Most of the changes were reversible, as exhibited by gill histopathology after the recovery period.

Biochemical and histopathological effects of glyphosate on carp, Cyprinus carpio L.

Glyphosate, also known by the trade names Roundup and Rodeo for agricultural use, is a broad-spectrum, translocated herbicide, used primarily in agricultural applications, and for vegetation control in non-crop areas. It is used as non-selective herbicide and for aquatic weed control in fish-ponds, lakes, canals, slow running water, etc. (USDA 1984). Glyphosate is perhaps the most important herbicide ever developed. Literature of toxicological and ecotoxicological properties of glyphosate is extremely sparse, considering its importance as herbicide. Generally, glyphosate is slightly toxic to mammals and fish, but it may have an impact on the aquatic environment and also on the other aquatic organisms (USDA 1984). Due to this, its toxicity investigation is very important. The study of sublethal effects is of special importance for toxicological evaluation of compound. The objective of this study was to investigate acute and subacute toxic effects of sublethal glyphosate concentrations in water to carp (Cyprinus carpio L.), one of the commercially most important fish species populating freshwaters of Yugoslavia.

Acute and subacute toxicity of atrazine to carp (Cyprinus carpio L.).

Investigations of acute and subacute atrazine toxicity in carp (Cyprinus carpio L.) were carried out. Acute toxicity was investigated in a semi-static test during a 96-hr exposition. The estimated LC-50 value was 18.8 mg/l. Subacute toxicity was investigated by exposing fish (carp) to different atrazine concentrations (1.5, 3.0, and 6.0 mg/l) for 14 days. Biochemical and histopathological changes in certain organs and tissues were investigated. The results show that atrazine leads to changes of varying intensity depending on the parameter tested, the organs and tissues examined, as well as the atrazine concentration. Biochemical changes were most prominent in the alkaline phosphatase, glutamic-oxaloacetic transaminase, and glutamic-pyruvic transaminase activities whereas the most severe histopathological changes were observed in the gills.