In this study, the purpose was to investigate the histopathological, genotoxic effect, oxidative stress and cell death due to Metronidazole (MTZ), which is a 5-nitroimidazole compound used widely for the treatment of anaerobic organism infections in fish and humans on gill and liver tissues of Oncorhynchus mykiss.Trout fishes were exposed to 5, 10, and 20 mg/L of MTZ in the aquariums for 2, 4 and 8 days. Staining technics namely H&E, NOS immunohistochemistry, and TUNEL were performed to determine histopathological changes, oxidative damage and apoptosis. Additionally, smear preparations were also prepared from gill blood for genotoxic evaluations. The organ damage started in the 2nd day with 5 mg/L MTZ application and effects increased per duration and dose-dependent manner. It was observed that the gills had the primary and secondary lamellae lengths, with formation of clavate lamellae, fusion in secondary lamellae, separation of epithelium and aneurysm. Regional necrosis, vacuolization of hepatocytes, pycnotic nucleus, enlarged sinusoids were also determined in the liver. NOS immunoreactivity increased with the inducible immunoreactivity (iNOS) that was more prominent when compared to the endothelial immunoreactivity (eNOS). Apoptotic immunoreactivity was higher in the 10 mg 8th day experimental group at liver and gills, and was lower 20 mg 8th day experimental group. When the gills and liver compared with each other, in all doses, immunoreactivity was lower in gills, compared with liver. Genotoxic examinations showed that both number of micronucleated erythrocytes and nuclei abnormalities were higher in MTZ-treated groups.

This scientific article presents the results of studies on the distribution of natural and artificial radionuclides in fish living in the rivers of the northwestern sector of the Arctic zone of the Russian Federation. Fish sampling (about 76 kg in total) was carried out in the White Sea, in the Northern Dvina and Mezen Rivers, and in the Sukhoe Sea Bay of the Arkhangelsk Region, as well as in the rivers of the Nenets Autonomous District: Pesha, Oma, Vizhas, Nes, and Pechora. The results showed the presence of artificial radionuclides Cs-137 and Sr-90 in fish only in the Nes River of the Nenets Autonomous District. The levels of radionuclides in whole bodies perch and pike in the Nes River range from 3.73 to 14.0 Bq/kg wet weight for Cs-137 and less than 3.72 to 23.1 Bq/kg wet weight for Sr-90. In addition to Cs-137 and Sr-90, the presence of the radionuclide K-40, which is the main dose-forming radionuclide, was noted in the fish of all the studied rivers and seas. K-40 activity was in the reached values 138 Bq/kg for whole fish bodies. The only assumption that can explain the presence of artificial radionuclides in the fish of the Nes River is a possible radioactive trace formed as a result of global nuclear tests, including in the Novaya Zemlya archipelago. At the same time, it is noted that the current levels of technogenic radioactivity in fish from the Nes River do not pose a radiological hazard to the local population.

The present study evaluates health risk assessment for inhabitants who are exposed to chromium in fishes and vegetables of the Gulshan Lake. In the fish, chromium concentration has amounted to 2.2 to 149.7 mg/kg, while in vegetables leaf and vegetables stem it has been 5.6 mg/kg and 12.0 mg/kg, respectively. What is more, in sediment it has been 179.5 to 308 mg/kg and in water, 4.0 to 16.9 mg/l. Higher accumulation of chromium (149.7 mg/kg) has been found in a fish species, relatively most affordable for poor people, called Pangas (Pangasius pangasius). Therefore, due to consumption of this fish the resultant non-cancer health hazard indices to people, living nearby Gulshan Lake has been almost 10 times greater than those induced by safe average daily dosages of the respective chemical. Vegetable pathway is still safe in terms of non-carcinogenic health hazard but may be very likely to act as an additive. It is therefore important to immediately take some remedial measures to not only reclaim Gulshan Lake but prevent any further pollution also.

peer reviewed | The replenishment and persistence of marine species is contingent on dispersing larvae locating suitable habitat and surviving to a reproductive stage. Pelagic larvae rely on environmental cues to make behavioural decisions with chemical information being important for habitat selection at settlement. We explored the sensory world of crustaceans and fishes focusing on the impact anthropogenic alterations (ocean acidification, red soil, pesticide) have on conspecific chemical signals used by larvae for habitat selection. Crustacean (Stenopus hispidus) and fish (Chromis viridis) larvae recognized their conspecifics via chemical signals under control conditions. In the presence of acidified water, red soil or pesticide, the ability of larvae to chemically recognize conspecific cues was altered. Our study highlights that recruitment potential on coral reefs may decrease due to anthropogenic stressors. If so, populations of fishes and crustaceans will continue their rapid decline; larval recruitment will not replace and sustain the adult populations on degraded reefs.

International audience | Microplastics (MPs), widely present in aquatic ecosystems, can be ingested by numerous organisms, but their toxicity remains poorly understood. Toxicity of environmental MPs from 2 beaches located on the Guadeloupe archipelago, Marie Galante (MG) and Petit-Bourg (PB) located near the North Atlantic gyre, was evaluated. A first experiment consisted in exposing early life stages of zebrafish (Danio rerio) to MPs at 1 or 10 mg/L. The exposure of early life stages to particles in water induced no toxic effects except a decrease in larval swimming activity for both MPs exposures (MG or PB). Then, a second experiment was performed as a chronic feeding exposure over 4 months, using a freshwater fish species, zebrafish, and a marine fish species, marine medaka (Oryzias melastigma). Fish were fed with food supplemented with environmentally relevant concentrations (1% wet weight of MPs in food) of environmental MPs from both sites. Chronic feeding exposure led to growth alterations in both species exposed to either MG or PB MPs but were more pronounced in marine medaka. Ethoxyresorufin-O-deethylase (EROD) and acetylcholinesterase (AChE) activities were only altered for marine medaka. Reproductive outputs were modified following PB exposure with a 70 and 42% decrease for zebrafish and marine medaka, respectively. Offspring of both species (F1 generation) were reared to evaluate toxicity following parental exposure on unexposed larvae. For zebrafish offspring, it revealed premature mortality after parental MG exposure and parental PB exposure produced behavioural disruptions with hyperactivity of F1 unexposed larvae. This was not observed in marine medaka offspring. This study highlights the ecotoxicological consequences of short and long-term exposures to environmental microplastics relevant to coastal marine areas, which represent essential habitats for a wide range of aquatic organisms.

International audience | Current European Union regulation regarding polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in food and feed is based on Toxic Equivalent Quotient (TEQ) concept. For confirmatory purpose, the isotope-dilution method associated to a measurement by gas chromatography coupled with high resolution mass spectrometry is usually the method of choice for precisely measuring the 29 target congeners in three separated fractions. Time and cost related to these analyses are very significant. Various kinds of screening concepts can be considered. In the present study, we elaborated and validated a prediction model for the 2005 World Health Organization TEQ in fish, based on the measurement of 4 PCDD/F and 2 non-ortho dl-PCB congeners, potentially analyzable in a single extracted fraction by gas chromatography coupled with mass spectrometry. Large independent datasets have been used for model elaboration (n = 108) and validation (n = 363, n = 357 and n = 6).

peer reviewed | Anthropogenic particles (APs), including microplastics, are ingested by a wide variety of marine organisms. Exposure of Clupeiformes (e.g. herrings, anchovies, sardines) is poorly studied despite their economic and ecological importance. This study aims to describe the morphology of the filtration apparatus of three wild-caught Clupeiformes (Sardina pilchardus, Clupea harengus and Engraulis encrasicolus) and to relate the results to ingested APs. Consequently, the species with the more efficient filtration apparatus will be more likely to ingest APs. We hypothesized that sardines were the most exposed species. The filtration area and particle retention threshold were determined in the three species, with sardines displaying the highest filtration area and the closest gill rakers. Sardines ingested more fibers and smaller fragments, confirming that it is the most efficient filtering species. These two results lead to the conclusion that, among the three studied, the sardine is the species most exposed to APs.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA | Among the numerous PCB congeners, most of the dioxin-like PCBs (DL-PCBs) need to be characterized by hyphenated techniques. It has been shown in several instances that these congeners are well related to the total PCB content in fish.We examined datasets collected mainly in France, on freshwater and marine fish and sediments. A statistical model linking DL- and indicator PCBs was developed for a dataset composed of freshwater fishes, and proved to predict well DL-PCBs from indicator PCBs in all other fish sets, including marine ones. Type II error rates remained low in almost all fish sets. A similar correlation was observed in sediments. Non-dioxin-like PCBs elicit various adverse effects and represent 95% of the total PCBs. A European guideline for them is needed; the correlation between DL- and indicator PCBs could help develop this standard in the future.

International audience | The concentrations of polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), pentachlorobenzene (PeCB) and polybrominated diphenylethers (PBDE) were described in benthic and pelagic species collected off Adélie Land, Antarctica. Strong differences were observed among species, with reduced PeCB and HCB levels in benthic species, and elevated PCB levels in the Antarctic yellowbelly rockcod, the Antarctic sea urchin and the snow petrel. Lower-chlorinated congeners were predominant in krill; penta-PCBs in benthic organisms; hexa- and hepta-PCBs in seabirds and cryopelagic fish. This segregation may result from sedimentation process, specific accumulation and excretion, and/or biotransformation processes. The presence of PBDEs in Antarctic coastal organisms may originate from atmospheric transport and partly from a contamination by local sources. Although POP levels in Antarctic marine organisms were substantially lower than in Arctic and temperate organisms, very little is known about their toxic effects on these cold-adapted species, with high degree of endemism.