High temperature aggravates the effects of pesticides in goldfish.

In human-altered rivers, fish are often conjointly exposed to an increase in water temperature due to global warming and to a contamination by organic pollutants such as pesticides, but their combined effects are still elusive. Thermal and chemical stressors could potentially interact because high temperature increases metabolism and toxicant uptake, and can alter the ability of organisms to set up adequate stress responses and to maintain homeostasis. These combined stressors could thus potentially result in higher level of molecular and cellular damage, and stronger effects on behavior and physiology, but experimental evidence across biological levels is still scarce. In this study, goldfish Carassius auratus were experimentally exposed to an environmentally realistic cocktail of pesticides (S-metolachlor, isoproturon, linuron, atrazine-desethyl, aclonifen, pendimethalin and tebuconazol) commonly found in rivers of South-West of France at low or high dose in two different thermal conditions: a common summer temperature (22 °C) or a high temperature recorded during heat waves (32 °C). Results showed that high temperature alone caused behavioral and physiological changes (increased swimming activity, increased hepatosomatic index, decreased reproductive index) but limited cellular damage. However, high temperature aggravated the effects of pesticides at the molecular and cellular level. Indeed, pesticide exposure resulted in higher genotoxic effects (micronuclei rate) and irreversible cellular damage of the gills and liver (apoptosis, inflammation, necrosis) at 32 °C compared to 22 °C. This suggests potential synergistic effects of climate change and pollution, and highlights the need for multiple stress approaches to better predict the impacts of human activities on aquatic wildlife.

Phthalate metabolites in the European eel (Anguilla anguilla) from Mediterranean coastal lagoons.

The levels and fate of phthalate metabolites have been poorly evaluated in fish, despite their potential ecotoxicological impacts. The present study aims to characterize the levels of phthalate metabolites in muscle tissue of yellow eels (Anguilla anguilla) from two coastal Mediterranean lagoons, during three sampling periods. Nine phthalate metabolites were detected in >70% of the samples. Slightly higher levels of phthalate metabolites were detected in March and June compared to October, suggesting possible seasonal variations in environmental release and/or phthalate metabolization process by eels. The large sample size (N=117) made it possible to explore correlations between phthalate metabolites' levels and individual parameters, such as body length, age, body condition and hepatic histo-pathologies. Body length and estimated age poorly correlated with phthalate metabolites, suggesting that eels did not accumulate phthalates during growth, contrary to persistent compounds. Eels presented different grades of hepatic fibrosis and lipidosis. A negative correlation was found between the severity of these pathologies in the liver and the sum of phthalate metabolites levels, supporting the hypothesis that eels with damaged liver are less able to metabolize xenobiotics.

Polychlorinated biphenyls in freshwater salmonids from the Kerguelen Islands in the Southern Ocean.

The Subantarctic Kerguelen Islands (49°S, 70°E) contain freshwater ecosystems among the most isolated in the world. Concentrations of polychlorinated biphenyls (PCBs) were assessed in the muscle of 48 brook trout and 38 brown trout caught during summer and spring 2006 in the rivers, lakes and ponds of Kerguelen. The sum of 29 PCBs averaged 404 and 358 ng g(-1) lipid, and dioxin-like PCB was 19 and 69 ng g(-1) lipid, in brook and brown trout, respectively. The values showed a high variability and some fish accumulated PCBs at levels similar to those of fish from impacted areas. While inter-sex differences were limited, the season and the morphotype appeared to have the most influence. Fish captured in summer had muscle PCB concentrations about three times higher than those caught in spring and the 'river' morphotype of brook trout showed the highest PCB levels.

Immunology-related perturbations induced by copper and chitosan in carp (Cyprinus carpio L.).

Copper is used in treatment mixtures to control fungal diseases in vineyards. Its concentrations are relatively high in some aquatic ecosystems, and the main problem observed in this study was the antioxidant stress induced by this heavy metal. Copper toxicologic effects in aquatic organisms have prompted the demand for alternative use of low-toxicity molecules in culture treatments. Chitosan is a polymer with antifungal property similar to copper and may be an interesting biopesticide. Thus, it is necessary to investigate the potential toxicity of chitosan for aquatic animal health, either alone or in conjunction with copper. In this study, carp were exposed to two sublethal chitosan concentrations (75 and 150 mg/L) or to two sublethal copper concentrations (0.1 and 0.25 mg/L) or to a mixture of chitosan plus copper (75 mg/L and 0.1 mg/L, respectively). The results of the present study show that exposure to copper at environmentally realistic levels or to chitosan at sublethal concentrations may significantly stimulate various aspects of immune functions in carp such as nonspecific cellular immunity, represented by total immunoglobulin level, ceruloplasmin activity, and oxidative activity of phagocytes. This acute-phase inflammatory response induced separately by the two treatments was not observed, especially on phagocyte oxidative activity, when carp were exposed to the copper-chitosan mixture. This fact could be explained by a possible chelation of copper by chitosan decreasing the biodisponibility of the two products for immune cells. Thus, the immunotoxicologic impact of copper and chitosan on fish immune response would be less pronounced with the combined treatments than with separate treatments in an aquatic environment.

Metallothionein induction in aquatic oligochaete tubifex tubifex exposed to herbicide isoproturon.

Metallothioneins (MTs) are low-molecular-weight proteins mainly involved in metal ion detoxification. Recently it has been demonstrated that MTs participate in several cellular functions such as regulation of growth and antioxidative defenses. Moreover, pesticides can induce their synthesis. The aim of the current work was to determine the effects of isoproturon, either pure or formulated as Matin (suspension containing an isoproturon concentration of 500 g. L(-1)), on the metallothionein and total protein contents of the aquatic worm Tubifex tubifex. MT levels in exposed worms increased significantly after 7 and 15 days of exposure to a concentration of the herbicide of 50 mg. L(-1). Isoproturon reduced the metal (Cu, Zn, and Cd) content of metallothioneins, and it also increased the total protein content of the worms. These results suggest that MT induction may not be considered a specific biomarker of metal exposure but that it can be used as a nonspecific biomarker of the effect of isoproturon effect in aquatic worms.

Metallothionein induction in the aquatic oligochaete Tubifex tubifex exposed to the herbicide isoproturon.

Metallothioneins (MTs), are low molecular weight proteins, mainly involved in metal ion detoxification. Recently it has been demonstrated that MTs participate in several cellular functions such as regulation of growth, and anti-oxidative defenses. Moreover, pesticides can induce their synthesis. The aim of the current work was to determine the effects of isoproturon either pure or formulated as Matin (suspension containing 500 g x l(-1) isoproturon) on the metallothionein and total protein content of the aquatic worm Tubifex tubifex. MT levels in exposed worms increased significantly after 7 and 15 days of exposure to 50 mg x l(-1) of herbicide. Isoproturon reduced metal (Cu, Zn, and Cd) content of metallothioneins, and it also increased total protein content of the worms. The results suggest that MT induction may not be considered as a specific biomarker of metal exposure but it can be used as a non specific biomarker of isoproturon effect in the worm.

Biological effects of two insecticides on earthworms (Lumbricus terrestris L.) under laboratory conditions.

Earthworms (Lumbricus terrestris L.) were exposed to endosulfan and aldicarb for 2, 7, and 15 days and lethal concentrations were determined. Worms were then exposed to these concentrations (LC10, LC25, and LC50) of endosulfan and (LC10 and LC25) of aldicarb. Growth rate, total protein content, and insecticide residues were determined. Aldicarb was more toxic than endosulfan and both insecticides caused a significant reduction of growth rate and total protein content of earthworms. Residues remaining in the soil after 2 to 15 days ranged between 37.75% and 68.54% of applied concentration for endosulfan and between 10.13% and 67.71% of applied concentration for aldicarb. Less than 1% of soil concentration was detected in worms and accumulation was more important in the case of endosulfan. This study proposes the use of growth rate and total protein content as biomarkers for contamination by endosulfan and aldicarb.

Fate and sublethal effects of isoproturon on mature earthworm (Lumbricus terrestris L.).

This study was conducted to investigate the effects of isoproturon in mature earthworm (Lumbricus terrestris L.) under laboratory condition. Earthworms were exposed to soils contaminated with different concentrations for various duration. Residues were monitored in soil and earthworms after 7, 15, 30, 45, and 60 days of exposure to different isoproturon concentrations. Acute toxicity of isoproturon was determined together with growth rate and total soluble protein content of worms. These parameters were related to isoproturon concentration in soil and earthworms. No lethal effect of isoproturon was observed even at the highest concentration tested (1.4 g/kg soil) after 60 days after treatment. Residues of isoproturon have caused a significant reduction of the growth rate. Additionally a reduction of total soluble protein was observed in all treated worms. Decrease of isoproturon concentration in soil was slow and depended on herbicide initial concentration. In the worms, it increased during the first 15 days and decreased thereafter. This study is suggesting the use of the growth rate of earthworms as biomarker of exposure to isoproturon.

Metallothioneins in liver of Rutilus rutilus exposed to Cu2+. Analysis by metal summation, SH determination and spectrofluorimetry.

Metallothioneins (MTs) have important roles in the homeostasis of essential metals and in the detoxication of heavy metals. They also represent a potential indicator of aquatic contamination by metals. Routine methods are needed for MTs quantification in ecotoxicological studies. This paper investigates the possibility to use the spectrofluorescent properties of Cu-MTs for MTs quantification. Cu displacement of metals coordinated to MTs and spectrofluorimetric determination of the obtained Cu-MTs was tested with commercial MTs and Cu2+-induced MTs in roach liver (Rutilus rutilus). Results of this original and simple spectrofluorimetric quantification of MTs presented a good correlation with data obtained with SH quantification, but not with metal summation evaluation of MTs (analysis of Zn, Cu and Cd coordinated to MTs). The three methods showed an clear induction of MTs in roach liver after 7 days of Cu2+ exposure. After 14 days of contamination, a reduction of hepatic MTs content was observable and not correlated to liver recovery. Results show that this low cost spectrofluorimetric method is useful to quantify MTs.

Biochemical and (ultra)structural hepatic perturbations of Brachydanio rerio (Teleostei, Cyprinidae) exposed to two sublethal concentrations of copper sulfate.

The aim of this study was to compare biochemical and (ultra)structural perturbations induced by Cu in the liver of Brachydanio rerio exposed for 14 days to sublethal concentrations of copper and then replaced for 14 days to clean water. Toxicity of Cu was clearly demonstrated: simultaneously to Cu accumulation, the liver developed large lysed areas and hepatocytic alterations. However, the majority of the parenchyma was composed of functional dark hepatocytes displaying typical feature of increased metabolism: development of rough reticulum, increase in size of nucleus and nucleolus, glycogenic depletion. Increase in hepatic protein content and of anti-oxidative defences (glutathione content, catalase and glutathione-S-transferase (GST) activities) indicated that the overall response of the liver was adaptative. In all hepatocytes a cord-like structure of the nucleoli was suspected to be associated to metal deposition. After 14 days depuration, the liver still contained high Cu concentrations and the hepatic alterations were not reversed. Such complementary studies are necessary for a better understanding of the deleterious effects of pollutants and for the development of biomarkers for metal toxicity.