The present paper reports on the interrelationships of fish, parasites and the bioaccumulation of hazardous organic compounds in the Zemplínska Šírava water reservoir in eastern Slovakia, which is heavily polluted with polychlorinated biphenyls (PCBs). The concentrations of these contaminants were measured in various fish matrices (dorsal and abdominal muscle tissues, hepatopancreas, intestine wall and adipose tissue) of the freshwater bream, Abramis brama (Cyprinidae), and in its intestinal parasite Caryophyllaeus laticeps (Cestoda), which was used for the first time as a model for a PCB bioaccumulation study. Regarding the fish, the highest concentrations of PCBs were found in the intestine, followed by hepatopancreas and muscle tissues. The amounts of PCBs were higher in abdominal muscles than in their dorsal parts. Concentrations of ∑PCBs above the limits set by European regulations were detected in both muscle parts in the fish, confirming the persistent unfavorable conditions in this locality and high risk for biota and humans. Based on bioconcentration factor values (BCFs), PCBs reached much higher levels in cestodes compared to bream matrices. Some significant differences in PCB amounts between infected and uninfected bream were determined. Fulton's condition factor (CF) significantly differed in infected and non-infected fish (p ˂ 0.05), with CF values surprisingly lower in fish free of parasites compared to parasitized fish, which suggests a “mutualistic” relationship between the parasite and its host.

The study addresses the topic of suitable matrices for chemical analysis in fish monitoring and discusses the effects of data normalization in the context of the European Water Framework Directive (WFD). Differences between species are considered by comparing three frequently monitored species of different trophic levels, i.e., chub (Squalius cephalus, n = 28), (bream, Abramis brama, n = 11), and perch (Perca fluviatilis, n = 19) sampled in the German Danube. The WFD priority substances dioxins, furans and dioxin-like polychlorinated biphenyls (PCDD/F + dl-PCB), polybrominated diphenyl ethers (PBDE), α-hexabromocyclododecane (α-HBCDD), hexachlorobenzene (HCB), mercury (Hg), and perfluorooctane sulfonic acid (PFOS) as well as non-dioxin-like (ndl)-PCB were analyzed separately in fillet and carcass and whole body concentrations were calculated. Hg was analyzed in individual fish fillets and carcasses, all other substances were determined in pool samples, which were compiled on the basis of fish size (3 chub pools, 1 bream pool, 2 perch pools). The data were normalized to 5% lipid weight (or 26% dry mass in the case of Hg and PFOS) for comparison between matrices and species.Hg concentrations were generally higher in fillet than in whole fish (mean whole fish-to-fillet ratio: 0.7) whereas all other substances were mostly higher in whole fish. In the case of lipophilic substances these differences leveled after lipid normalization.Significant correlations (p ≤ .05) were detected between Hg and fish weight and age. Hg concentrations varied least among younger fish. PCDD/F, dl-PCB, ndl-PCB, PBDE, α-HBCDD and HCB correlated significantly (p ≤ .05) with lipid concentrations. Fillet-to-whole fish conversion equations and/or conversion factors were derived for all substances except α-HCBDD. Although more data also for individual fish would be desirable the results are nevertheless a step on the way to translate fillet concentrations of priority substances to whole fish concentrations.

Under the German environmental specimen bank programme bream (Abramis brama) were sampled in six German rivers and analysed for the priority hazardous substances dicofol, hexabromocyclododecane (HBCDD), hexachlorobenzene (HCB), hexachlorobutadiene (HCBD), heptachlor + heptachlor epoxide (HC + HCE), polybrominated diphenylethers (PBDEs), polychlorinated dibenzo-p-dioxins and -furans and dioxin-like polychlorinated biphenyls (PCDD/Fs + dl-PCBs), and perfluorooctane sulfonic acid (PFOS). The aim was to assess compliance with the EU Water Framework Directive environmental quality standards for biota (EQSBiota) for the year 2013, and to analyse temporal trends for those substances that are of special concern. General compliance was observed for dicofol, HBCDD and HCBD whereas PBDEs exceeded the EQSBiota at all sites. For all other substances compliance in 2013 varied between locations. No assessment was possible for HC + HCE at some sites where the analytical sensitivity was not sufficient to cover the EQSBiota. Trend analysis showed decreasing linear trends for HCB and PFOS at most sampling sites between 1995 and 2014 indicating that the emission reduction measures are effective. Mostly decreasing trends or constant levels were also observed for PCDD/Fs and dl-PCBs. In contrast, increasing trends were detected for PBDEs and HBCDD which were especially pronounced at one Saar site located downstream of the industries and conurbation of Saarbrücken and Völklingen. This finding points to new sources of emissions which should be followed in the coming years.

High levels of trace elements in aquatic environments can affect the quality of seafood. We analyzed the concentrations of As, Cd, Co, Hg, Mn, Ni and Pb, in the edible muscles of Hemiculter leucisculus and A. brama orientalis caught in four different areas of southwest of the Caspian Sea. We estimated the potential risks for human health deriving by the oral consumption of these two species, and the Target Hazard Quotient (THQ) according to the US-EPA approach. THQ by adults and children was always below 1 for all stations. The greater contribution was given by Co, followed by Cd, Hg, Pb, Ni, As and Mn. Total-THQ was 0.538 and 0.246 for children and adults, respectively. Trace elements detected by our study were not elevated, highlighting a positive picture of the studied area and a lower risk of developing chronic systemic effects deriving from the consumption of local fish products.

The paper presents the results of preliminary study of the intestinal content in bream (Abramis brama L. 1758) of the Danube River through the Belgrade Region. The fishes were collected in May and October during the period 2007-2009 at two sampling sites along the course. A total of 42 fish specimens of different age (2+ to 6+) were examined. By examination of compositing of intestine of bream have been found members from macrozoobentho-groups – Oligochaeta, Gastropoda (Lithoglyphus naticoides), Bivalvia, Amphipoda (Gamaridae). Our investigation showed that the diet of bream is dependent of bottom fauna composition and structure.

Anticoagulant rodenticides (ARs) have been used for decades for rodent control worldwide. Research on the exposure of the environment and accumulation of these active substances in biota has been focused on terrestrial food webs, but few data are available on the impact of ARs on aquatic systems and water organisms. To fill this gap, we analyzed liver samples of bream (Abramis brama) and co-located suspended particulate matter (SPM) from the German Environmental Specimen Bank (ESB). An appropriate method was developed for the determination of eight different ARs, including first- and second-generation ARs, in fish liver and SPM. Applying this method to bream liver samples from 17 and 18 sampling locations of the years 2011 and 2015, respectively, five ARs were found at levels above limits of quantifications (LOQs, 0.2 to 2 μg kg⁻¹). For 2015, brodifacoum was detected in 88% of the samples with a maximum concentration of 12.5 μg kg⁻¹. Moreover, difenacoum, bromadiolone, difethialone, and flocoumafen were detected in some samples above LOQ. In contrast, no first generation AR was detected in the ESB samples. In SPM, only bromadiolone could be detected in 56% of the samples at levels up to 9.24 μg kg⁻¹. A temporal trend analysis of bream liver from two sampling locations over a period of up to 23 years revealed a significant trend for brodifacoum at one of the sampling locations.

Piscifaunal health depends upon the state and quality of the aquatic environment. Variations in physical condition of fish may therefore be attributed to changes in environmental quality. Based on time series of up to 20 years of biometric data of bream from multiple sampling sites of the German environmental specimen bank (ESB), this study assessed whether changes in biometric parameters are able to indicate long-term alterations in fish health and environmental quality. Evaluated biometric parameters of fish health comprised length and weight of individuals of a defined age class, the condition factor, lipid content and hepatosomatic index (HSI). Although there are negative trends of the HSI, the overall development of health parameters can be interpreted as positive. This seems to suggest that health parameters conclusively mirror the long-term improvement of water quality in the selected rivers. However, the applicability of the condition factor as well as lipid content as indicators for fish health remained subject to restrictions. Altogether, the results from the ESB confirmed the high value of biometric parameters for monitoring of long-term changes in state and quality of aquatic ecosystems.

This study examines the use of freshwater bream (Abramis brama) as a sentinel organism for genotoxicity assessment of the Danube River using the comet assay. Sampling of bream was performed during February, April, August, and November in 2014 to assess seasonal variation of DNA damage level as a response to genotoxicity in annual cycle. Additionally, concentrations of fecal coliforms and enterococci were analyzed and they indicated a critical to strong level of fecal pollution on investigated locality during annual cycle. Comet assay was performed on blood, liver, and gill cells of bream. DNA damage level was expressed using tail intensity (TI %), Olive tail moment (OTM), and tail length (TL pix). According to TI and OTM, all three tissues had the highest level of DNA damage in August. The lowest level of DNA damage in liver was measured during February, in blood during November, and in gills during April. According to TL, gills had the highest level of DNA damage in February, and liver cells had the lowest level of damage during April. Multiple correspondence analysis (MCA) showed that DNA damage in blood cells is under the strong influence of variations in NO₂, NO₃ ⁻, NH₄ ⁺ levels and also the variation in temperature and oxygen levels. DNA damage in liver cells is highly associated with the variations of Mn, Fe, Cu, Zn, and PO₄ ³⁻ levels. DNA damage in gill cells is strongly affected by the variations of As, Cd, Pb, Cr, and COD (Mn) levels. Freshwater bream is shown to be a potentially good indicator organism in genotoxic potential field studies.

The brominated flame retardant hexabromocyclododecane (HBCD) was monitored in fish and sediment (from one lake) or suspended particulate matter (SPM; from five rivers) at European freshwater sites to study the effects of reduction measures implemented by HBCD producers and users in recent years. Bream (Abramis brama) were sampled annually between 2007 and 2013 in the rivers Götaälv/SE, Rhône/FR, Western Scheldt/NL, Mersey/UK, and Tees/UK and in Lake Belau/DE. Sediment/SPM was taken every second year between 2008 and 2014. HBCD was analyzed by LC/MS/MS allowing the determination of the alpha-, beta-, and gamma-diastereomers. For most sites, a decrease in ∑HBCD was observed in fish (e.g., in the Rhône and Western Scheldt by about 80 and 60%, respectively, with significantly decreasing trends, p < 0.01). In the Rhône, HBCD also decreased in SPM. At the sampling site in the Tees which was impacted by a former HBCD point source, fish HBCD levels decreased only after a major flood event in 2013. While fish data indicate a decline in environmental HBCD concentrations at most sites with diffuse emissions, SPM data were less conclusive. The European environmental quality standard for HBCD in fish of 167 μg kg⁻¹ wet weight was met by all fish samples in 2013.

The study monitored the contamination of fish muscle tissue by elements Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn at 17 sampling sites, in order to assess the pollution status of the main rivers in Serbia. Of the six commercially important fish species included in the study (pikeperch Sander lucioperca, catfish Silurus glanis, bream Abramis brama, barbel Barbus barbus, chub Squalius cephalus, nase Chondrostoma nasus), the bioconcentration factor (BCF) indicated that benthivore bream and barbel and predatory catfish have the highest tendency toward the accumulation of elements. This study achieved its primary objective and produced a contamination map of Serbia as a basis for further research. The estimated metal pollution index (MPI) showed the Tisa River to be unaffected by direct pollution (with an MPI value of 0.31) and the West Morava and Pek rivers to be affected (with MPI values of 1.92 and 0.73 for the WM₁ and WM₂ sampling sites and 0.65 for the Pek sampling site). Over the past two decades, Serbia has not expanded its industrial activity, which has resulted in the barely noticeable anthropogenic input of heavy metals in the rivers close to industry, and the main rivers are mostly unaffected and slightly affected. We assumed that pollution by heavy metals in the 1990s was trapped in the sediment, thus showing an increased concentration of elements in the species that live and feed on the bottom. Hg concentrations exceeded the maximum permitted concentrations (MPCs) only in catfish samples (0.62 mg kg⁻¹) from the Danube (D₃ sampling site) and barbel (0.78 mg kg⁻¹) from the West Morava (WM₁ sampling site), while Cd concentrations exceeded the MPC in catfish samples (0.09 mg kg⁻¹) from the Danube (D₁ sampling site) and chub samples (0.1 mg kg⁻¹) from the South Morava (SM₂ sampling site). The average concentrations of Pb exceeded the MPC in chub and barbel samples (0.32 and 0.82 mg kg⁻¹, respectively) from the West Morava (WM₁ sampling site); chub, barbel, and nase samples (0.35, 0.32, 0.31 mg kg⁻¹, respectively) from the West Morava (WM₂ sampling site); chub and barbel samples (0.35 and 0.3 mg kg⁻¹, respectively) from the Ibar; chub samples (0.39 mg kg⁻¹) from the Drina; chub and barbel samples (0.59 and 0.4 mg kg⁻¹, respectively) from the Great Timok; and nase samples (0.33 mg kg⁻¹) from the Pek. These results demonstrate that there is a need for future studies that would involve similar analyses and focus especially on smaller rivers that have been neglected so far.