Metabolome adaptation and oxidative stress response of common carp (Cyprinus carpio) to altered water pollution levels.

Treated wastewater ponds (TWPs) serve as recipients and passive tertiary treatment mediators for recycled water. These nutrient-rich habitats are increasingly utilised in aquaculture, nevertheless multiple loads of various contaminants with adverse effects on aquatic fauna, including fish, have been recorded. In the present study, we investigated the effects of fish transfer in response to altered levels of pollution on liver metabolic profiles and tissue-specific oxidative stress biomarkers during short- and long-term exposure. In a field experiment, common carp (Cyprinus carpio) originating in severely polluted TWP were restocked after one year to a reference pond with a background pollutant concentration typical of the regional river. In contrast, fish that originated in the reference pond were restocked to TWP. Fish were sampled 0, 7, 14, 60, and 180 days after restocking and fish liver, kidney, intestine, and gill tissues were subjected to biomarker analysis. Pharmaceutically active compounds (PhACs) and metabolic profiles were determined in fish liver using liquid chromatography high-resolution mass spectrometry (LC-HRMS). Fish transferred from reference to polluted pond increased the antioxidant response and absorbed PhACs into metabolism within seven days. Fish liver metabolic profiles were shifted rapidly, but after 180 days to a lesser extent than profiles in fish already adapted in polluted water. Restocked fish from polluted to reference pond eliminated PhACs during the short phase within 14 days, and the highest antioxidant response accompanied the depuration process. Numerous elevated metabolic compounds persisted in such exposed fish for at least 60 days. The period of two weeks was suggested as sufficient for PhACs depuration, but more than two months after restocking is needed for fish to stabilise their metabolism. This study contributed to determining the safe handling with marketed fish commonly restocked to wastewaters and clarified that water pollution irreversibly altered fish metabolic profile.

Natural Feed Additives Modulate Immunity and Mitigate Infection with Sphaerospora molnari (Myxozoa:Cnidaria) in Common Carp: A Pilot Study.

Myxozoans are a diverse group of cnidarian parasites, including important pathogens in different aquaculture species, without effective legalized treatments for fish destined for human consumption. We tested the effect of natural feed additives on immune parameters of common carp and in the course of a controlled laboratory infection with the myxozoan Sphaerospora molnari. Carp were fed a base diet enriched with 0.5% curcumin or 0.12% of a multi-strain yeast fraction, before intraperitoneal injection with blood stages of S. molnari. We demonstrate the impact of these treatments on respiratory burst, phagocytosis, nitric oxide production, adaptive IgM+ B cell responses, S. molnari-specific antibody titers, and on parasite numbers. Both experimental diets enriched B cell populations prior to infection and postponed initial parasite proliferation in the blood. Curcumin-fed fish showed a decrease in reactive oxygen species, nitric oxide production and B cell density at late-stage infection, likely due to its anti-inflammatory properties, favoring parasite propagation. In contrast, multi-strain yeast fraction (MsYF)-fed fish harbored the highest S. molnari-specific antibody titer, in combination with the overall lowest parasite numbers. The results demonstrate that yeast products can be highly beneficial for the outcome of myxozoan infections and could be used as effective feed additives in aquaculture.

Parasite-induced increases in the energy costs of movement of host freshwater fish.

Parasitization by the larvae (glochidia) of freshwater mussels can cause harm to a fish's gills, resulting in less effective respiration and/or reduced activity by the host fish. The impact of glochidia infections on the host's physiology remains poorly understood, and no information is available concerning energy consumption in parasitized fish. Hence, we obtained glochidia of the invasive unionid mussel Sinanodonta (Anodonta) woodiana and experimentally infected common carp, Cyprinus carpio, tagged with physiological sensors to measure energy consumption. We tested the hypothesis that parasitization affects energy consumption in the host fish, reflected as higher energy costs for movement and reduced movement activity over eight days post-infection within a twenty-four-hour cycle. Parasitized fish showed higher energy costs of movement; however, no changes in movement activity were found compared with activity in control fish. Significantly increased biochemical indices were measured in host fish blood samples, including aspartate (AST) and alanine (ALT) aminotransferase levels, indicating liver injury, and high concentrations of potassium (K+), signifying kidney injury (hyperkalemia). Increased Cl- concentrations indicate gill dysfunction. Our results show that the energy costs due to glochidia parasitization are independent of overall movement activity patterns and vary in time according to the parasitic phase and the diurnal cycle. Moreover, the side effects of parasitization have a more important impact on fish hosts than has been shown in previous reports.

Comparison of the effect of four anaesthetics on haematological profiles, oxidative stress and antioxidant enzymes in barbel (Barbus barbus).

OBJECTIVES: Currently, many questions regarding the effect of anaesthetics to fish remain unresolved. Fish species may differ widely in their response to an anaesthetic, the screening of dosages is often necessary. The aim of this study was to compare the effect of tricaine methane sulphonate (MS 222), clove oil, 2-phenoxyethanol and Propiscin on haematological profiles, oxidative stress biomarkers and antioxidant enzymes in barbel (Barbus barbus). DESIGN: The haematological profiles, oxidative stress biomarkers and antioxidant enzymes of barbel were evaluated immediately after a 10 min anaesthesia (MS 222--100 mg.L(-1), clove oil--33 mg.L(-1), 2-phenoxyethanol--0.4 mg.L(-1), Propiscin--1.0 mg.L(-1)), and 24 h after anaesthesia. RESULTS: The 10 min exposure in the recommended concentrations of tested anaesthetics have no significant effect on haematological profiles, levels of thiobarbituric acid reactive substances, and activity of glutathione reductase of barbel. The activity of superoxide dismutase (SOD) was significantly decreased (p<0.01) in the muscle in all experimental groups. The activity of SOD showed a significant decrease (p<0.01) in the liver 24 h after all anaesthetics; however in the gill the activity of SOD was significantly increased (p<0.01) in Propiscin (10 min). The activity of catalase (CAT) was significantly increased (p<0.05) in the muscle 24 h after all anaesthetics. CONCLUSIONS: The observed effects on barbel antioxidant systems may be a defence against oxidative damage. The results of this study suggest that the antioxidant systems of barbel are altered by Propiscin anaesthesia, but are slightly affected by MS 222, clove oil, and 2-phenoxyethanol anaesthesia.

Contamination of fish in important fishing grounds of the Czech Republic.

The aim of this study was to compare the contamination levels of certain important fishing grounds in the Czech Republic and to assess the health risk of consuming the fish from these localities. The assessment was performed from 2006 to 2010 in 27 fishing grounds. Within this project, 707 fish from 14 different species were sampled. The concentration of selected toxic metals (Hg, Pb, Cd) and persistent organic pollutants (POPs), such as non-dioxin-like polychlorinated biphenyls (NDL-PCBs), hexachlorocyclohexane (HCH) isomers, dichlorodiphenyltrichloroethane (DDT) and its metabolites (o,p´-DDE; p,p´-DDE; o,p´-DDD; p,p´-DDD; o,p´-DDT; p,p´-DDT) and hexachlorobenzene (HCB), were analysed in the muscle tissue of the sampled fish. Atomic absorption spectrometry (AAS) was used for the analysis of toxic metals. All of the POPs were analysed using gas chromatography with an electron capture detector (GC/ECD). Common bream (Abramis brama) was chosen as a reference fish species for the comparison of fishing grounds. Mercury was found as a major pollutant in fish flesh at all of the sampling sites. Concentrations in excess of the maximum level (ML) of mercury in the muscle tissue of fish (0.5 mg kg(-1)) were registered in 32 samples. Concentrations of other monitored toxic metals in fish muscle were low, typically below the limit of quantification (LOQ). From the tested POPs, DDTs and NDL-PCBs were found as major pollutants. ML for NDL-PCBs (ICES-6) in muscle tissue of fish (0.125 mg kg(-1)) was exceeded in 7 samples. In case of tested pesticides, concentrations in excess of the MRL were not registered.