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Members of the transforming growth factor β (TGF-β) signaling pathway regulate diverse cellular biological processes in embryonic and tissue development. We took mandarin fish (Siniperca chuatsi) as the research object to identify all members of the TGF-β signaling pathway, measure their expression pattern in the key period post hatching, and further explore their possible role in the process of sex regulation. Herein, we identified eighty-three TGF-β signaling pathway members and located them on chromosomes based on the genome of mandarin fish. TGF-β signaling pathway members were highly conserved since each TGF-β subfamily clustered with orthologs from other species. Transcriptome analysis, qRT-PCR and in situ hybridization demonstrated that most mandarin fish TGF-β signaling pathway members presented stage-specific and/or sex-dimorphic expression during gonadal development, and different members of the TGF-β signaling pathway participated in different stages of gonadal development. Taken together, our results provide new insight into the role of TGF-β signaling pathway members in the sex regulation of mandarin fish., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023. Published by Elsevier B.V.)

TNFα, as a pro-inflammatory cytokine, plays an important role in inflammation and immune homeostasis maintaining. However, the knowledge about the immune functions of teleost TNFα against bacterial infections is still limited. In this study, the TNFα was characterized from black rockfish (Sebastes schlegelii). The bioinformatics analyses showed the evolutionary conservations in sequence and structure. The expression levels of Ss_TNFα mRNA were significantly up-regulated in the spleen and intestine after Aeromonas salmonicides and Edwardsiella tarda infections, and dramatically down-regulated in PBLs after LPS and poly I:C stimulations. Meanwhile, the extremely up-regulated expressions of other inflammatory cytokines (especially for IL-1β and IL17C) were observed in the intestine and spleen after bacterial infection and down-regulations were obtained in PBLs. The significant regulation with expression patterns of Ss_TNFα and other inflammatory cytokine mRNAs illustrated the variations of immunity in different tissues and cells of black rockfish. The regulated functions of Ss_TNFα in the up/downstream signaling pathways were preliminarily verified on the transcription and translation levels. Subsequently, in vitro knockdown of Ss_TNFα in the intestine cells of black rockfish confirmed the important immune roles of Ss_TNFα. Finally, the apoptotic analyses were conducted in PBLs and intestine cells of black rockfish. The rapid increases of the apoptotic rates were obtained in both PBLs and intestine cells after treatment with rSs_TNFα, but distinct apoptotic rates at the early and late stages of apoptosis were observed between these two types of cells. The results of apoptotic analyses suggested that Ss_TNFα could trigger apoptosis of different cells in different strategies in black rockfish. Overall, the findings in this study indicated the important roles of Ss_TNFα in the immune system of black rockfish during pathogenic infection, as well as the potential function on biomarker for monitoring the health status., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Mitochondrial changes such as tight coupling of the mitochondria have facilitated sustained oxygen and respiratory activity in haemoglobin-less icefish of the Channichthyidae family. We aimed to characterise features in the sequence and structure of the proteins directly involved in proton transport, which have potential physiological implications. ATP synthase subunit a (ATP6) and subunit 8 (ATP8) are proteins that function as part of the F0 component (proton pump) of the F0F1complex. Both proteins are encoded by the mitochondrial genome and involved in oxidative phosphorylation. To explore mitochondrial sequence variation for ATP6 and ATP8 we analysed sequences from C. gunnari and C. rastrospinosus and compared them with their closely related red-blooded species and eight other vertebrate species. Our comparison of the amino acid sequence of these proteins reveals important differences that could underlie aspects of the unique physiology of the icefish. In this study we find that changes in the sequence of subunit a of the icefish C. gunnari at position 35 where there is a hydrophobic alanine which is not seen in the other notothenioids we analysed. An amino acid change of this type is significant since it may have a structural impact. The biology of the haemoglobin-less icefish is necessarily unique and any insights about these animals will help to generate a better overall understanding of important physiological pathways., Competing Interests: The authors have declared that no competing interests exist.

In the aftermath of the Great East Japan Earthquake of March 11, 2011, marine fish in Kesennuma Bay, Japan, have been contaminated with heavy oil containing polycyclic aromatic hydrocarbons (PAHs). To estimate the risk of six PAHs (benzo[α]pyrene, dibenzothiophene, phenanthrene, 2,3,5-trimethylnaphthalene, acenaphthene, and 1-methylphenanthrene), which have been detected at high levels in the tissues of fish from Kesennuma Bay, we attempted to evaluate the effects of these PAHs on the fish aryl hydrocarbon receptor (AHR) signaling pathway. We initially measured PAH concentrations and cytochrome P4501A catalytic activities (EROD: ethoxyresorufin-O-deethylase and MROD: methoxyresorufin-O-demethylase) as markers of AHR activation in greenlings (Hexagrammos otakii) collected from Kesennuma Bay in 2014. The results showed that alkylated PAH concentrations and EROD/MROD activities were higher in sites close to the oil-spilled sites than in the control site, suggesting AHR activation by spilled alkylated PAHs. We then investigated AHR-mediated responses to these PAHs in the in vitro reporter gene assay system where red seabream (Pagrus major) AHR1 (rsAHR1) or rsAHR2 expression plasmids were transiently transfected into COS-7 cells. The in vitro assay showed rsAHR isoform-, PAH-, and dose-dependent transactivation potencies. The relative effective concentrations of benzo[α]pyrene, dibenzothiophene, phenanthrene, 2,3,5-trimethylnaphthalene, acenaphthene, and 1-methylphenanthrene that induce 20% of the maximum benzo[α]pyrene response (REC 20-BaP ) for rsAHR1 activation were 0.052, 38, 79, 88, 270 nM, and no response, respectively, and those for rsAHR2 activation were 0.0049, 32, 53, 88, 60 nM, and no response, respectively. The results showed that the REC 20-BaP values of benzo[α]pyrene for both the rsAHR1 and rsAHR2 isoforms were lower than the concentrations (0.041-0.20 nM) detected in the muscle tissue of fish from Kesennuma Bay, while the REC 20-BaP values of other PAHs were higher than their tissue concentrations. In silico rsAHR homology modeling and subsequent ligand docking simulation analyses indicated that the rsAHR activation potencies of PAHs could be predicted from a rsAHR2 model. This study shows that in vitro and in silico rsAHR analyses may be a useful tool for assessing the risks to fish contaminated with PAHs., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Marine fish are considered a source of high quality proteins and fatty acids. However, the consumption of fish may pose a health risk as it may have potentially toxic elements in high concentrations. In this study we quantify the multielemental composition of muscle and fins for three species of commercial marine fish from Brazil: Sphyraena guachancho (Barracuda), Priacantus arenatus (Common bigeye) and Genidens genidens (Guri sea catfish). We then assessed the potential risk of fish consumption by means of a Provisional Hazard Indices. Amongst the elements detected in fish tissue were potentially toxic elements such as Ag, Ba, Cd, Cr and Hg. Concentration differences were species-specific, and affected by the species trophic level, morphological characteristics and feeding habits. Results suggest the higher the trophic level of the fish, the higher the risk of consumption. Caution is recommended for the frequent ingestion of high trophic level fish species in Brazil., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The gastrointestinal tracts of 229 demersal fish belonging to two species (Mullus barbatus, Merluccius merluccius) were examined for microplastic ingestion. Samples were collected in 3 different FAO Geographical Sub-Areas (GSA-9, GSA-17, GSA-19) of the Mediterranean Sea. Ingested microplastics were characterized using a stereo-microscope: observed, photographed, measured and categorized according to size class, shape and colour. Plastic fragments (ranging from 0.10 to 6.6 mm) were detected in 23.3% of the total investigated fish; a total of 65 plastic particles (66% constituted by fibers) were recorded. The percentage of plastic ingestion shows high variability between the two species and among the different sampling area. The highest frequency (48%) was found in European hake from GSA-19. These preliminary results represent a baseline for the implementation of the Marine Strategy Framework Directive descriptor 10 in Italy as well as an important step for detecting microplastics in bioindicator species from different GSAs., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The Total Maximum Daily Load (TMDL) for selenium in the freshwater drainages to Newport Bay, California, is being developed based on selenium concentration in the tissues of fish and bird eggs. This paper demonstrates the use of fish mesocosms and monitoring results to facilitate the comparisons of selenium contamination across fish species and areas of the watershed with differing fish assemblages. In this watershed, mosquitofish dominate across all the small, upper watershed drainages while sunfish family species dominate in deeper, ponded reaches of the lower watershed. Mesocosms were used to hold mosquitofish in ponds where they did not occur to compare their concentrations of bioaccumulated selenium to the tissue selenium of resident bluegill sunfish of the same pond. The caged fish were allowed to bioaccumulate selenium over time to achieve tissue concentrations at equilibrium conditions to compare as a ratio to resident bluegill. Those results were compared to the ratio of tissue concentrations from a later sampling of the same pond when the two species were found to co-occur for the first time. The ratios were brought into agreement only after altering assumptions of time to achieve equilibrium in bioaccumulated selenium for the transplanted mosquitofish and extrapolation of the mesocosm results. The technique demonstrates important considerations for the use of mesocosms to facilitate comparisons between allopatric species in terms of selenium bioaccumulation. A careful consideration of trophic level of the caged fish was found to be critical in setting the total time of bioaccumulation as part of the experimental design needed to achieve equilibrium tissue concentrations.

Bioaccumulation of mercury and methylmercury in fish represents a serious risk to human beings. Extreme climate events like droughts may increase the trophic transfer of contaminants and net methylation of mercury. The present study assessed the influence of the 2014 drought on total mercury and methylmercury levels in fish from the lower Paraiba do Sul river basin. Contaminant levels were compared for Pimelodus fur, Pachyurus adspersus, Pimelodella lateristriga, Oligosarcus hepsetus, and Crenicichla lacustris captured in five sites in 2013 (N = 212) and 2014 (N = 231). The results indicate that levels of contaminants were higher during the drought in most species. Rainfall was weakly and negatively correlated with total mercury levels in most of the species. The weak relationship between these two variables was due to the indirect influence of rainfall on mercury bioaccumulation. In summary, drought increased the levels of two contaminants in fish., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The health of a marine ecosystem can effectively be monitored by studying the levels of biomarkers in a representative species. A change in background level of a biomarker indicates exposure to a specific type of pollutants. It also identifies bioavailability and the organism response to the causative agent among the compounds present in the surrounding water body. Yellowfin seabream (Acanthopagrus latus), a local variety of fish, was examined for parent PAHs in the liver, its metabolites in bile by the GC-MS method as exposure biomarkers and cytochrome P4501A1 by assay of ethoxyresorufin-o-deethylase (EROD) in the liver as an effect biomarker. A comparison was made between fish collected in 2015 with the fish collected in 2005-2006 and stored at - 80 °C in the fish bank. The objective was to examine the extent of changes in the environmental quality of the Kuwait marine area and the status of fish health concerning oil-related pollutants since Arabian Gulf is surrounded by oil-producing countries. Interestingly, insignificant differences between the liver PAH content and EROD activity were observed in fish over the sampling periods. The fish efficiently metabolized PAHs and excreted hydroxy-metabolites in bile. The study suggested that environmental quality of the Kuwait marine area was not deteriorated to any serious extent in the last decade and biomarkers can be used effectively in assessing the thrust of sub-optimal levels of various contaminants present in the marine area on the resident biota.

Mariculture fish contains a rich source of protein, but some species may bioaccumulate high levels of heavy metals, making them unsafe for consumption. This study aims to identify heavy metal concentration in Lates calcarifer (Barramudi), Lutjanus campechanus (Red snapper) and Lutjanus griseus (Grey snapper). Three species of mariculture fish, namely, L. calcarifer, L. campechanus and L. griseus were collected for analyses of heavy metals. The concentration of heavy metal (As, Cd, Cu, Cr, Fe, Pb, Mn, Ni, Se, and Zn) was determined using inductive coupled plasma mass spectrometry (ICP-MS). The distribution of heavy metals mean concentration in muscle is Zn > Fe > As > Se > Cr > Cu > Mn > Pb > Ni > Cd for L. calcarifer, Fe > Zn > Cr > As > Ni > Mn > Se > Cu > Pb > Cd for L. campechanus and Fe > Zn > Cr > Ni > Se > Cu > As > Mn > Pb > Cd for L. griseus. Among all of the species under investigation, the highest concentration of Fe was found in the muscle tissue of L. campechanus (19.985 ± 1.773 mg kg -1 ) and liver tissue of L. griseus (58.248 ± 8.736 mg kg -1 ). Meanwhile, L. calcarifer has the lowest concentration of Cd in both muscle (0.007 ± 0.004 mg kg -1 ) and liver tissue (0.027 ± 0.016 mg kg -1 ). The heavy metal concentration in muscle tissue is below the permissible limit guidelines stipulated by the Food & Agriculture Organization, 1983 and Malaysia Food Act, 1983. The concentration of heavy metals varies significantly among fish species and tissues. L. campechanus was found to have a higher ability to accumulate heavy metals as compared to the other two species (p < .00). Among all the studied fish, liver tissue has a higher concentration of heavy metals compared to muscle tissue (p < .05). The findings from this study can serve as baseline information for future monitoring and risk assessment studies. Periodic monitoring of heavy metal concentration in mariculture fish must be performed to prevent acute and chronic food intoxication., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

It has been suggested that High-Antarctic waters, despite their remoteness from human activities, are impacted by anthropogenic pollution, and that the local biota are accumulating the contaminants. At present, no data exist on persistent organic pollutant (POP) body burdens for notothenioid fish inhabiting the High-Antarctic Weddell Sea. We determined the pollutant load in white muscle tissue of red- and white-blooded notothenoids from the Weddell Sea (Trematomus loennbergii and Chionodraco hamatus, respectively), and compared them to our previous measurements of POPs in Low-Antarctic notothenioids. Analytes included various organochlorine pesticides (OCPs), polychlorinated biphenyls (indicator (i) PCBs, dioxine-like (dl) PCBs) and polybrominated diphenyl ethers (PBDEs). The analytical concentrations were converted into 2,3,7,8-TCDD toxic equivalents (TEQs). Compared to T. loennbergii, C. hamatus had lower levels of β-HCH (0.45 vs. 4.5 ng g -1 lipid weight), and Σ iPCBs (30 vs. 39 ng g -1 lipid weight), as well as lower levels of Σ PBDEs (131 vs. 261 ng g -1 fresh weight). POP body burdens and TEQs were mostly similar to those of Low-Antarctic notothenioids analysed previously, and not related to the trophic positions of the species. The variations in POP levels between and within High- and Low-Antarctic notothenioids only marginally corresponded to sampling site, ecological differences or trophic levels of the species, and might rather be related to metabolism or age effects. The present findings suggest that fishes of High-Antarctic waters, although this area is more remote and less influenced by local human activities, do not show lower POP body burdens than fishes from Low-Antarctic waters., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The objective of the present study was to assess the effect of short-term (2-144 h) heat stress (8 °C) on energy production processes and antioxidant defense systems in the kidneys and gills of Notothenia rossii and Notothenia coriiceps. Heat stress affected energy metabolism and oxidative stress parameters in a time-, tissue-, and species-dependent manner, and gills were more sensitive than kidneys to heat stress. N. rossii kidneys were able to stabilize carbohydrate metabolism after 12 h of heat stress, whereas the glycogen levels in N. coriiceps kidneys fluctuated in response to varying glucose-6-phosphatase (G6Pase) levels. The gills of N. rossii were able to stabilize their energy demand and aerobic metabolism under heat stress, whereas in the gills of N. coriiceps, changes in carbohydrate metabolic pathways depended on the exposure time: initially, anaerobiosis was activated after 6 h; the energy demand, characterized by glycogen consumption, increased after 72 h, and aerobic metabolism was activated within 144 h. With regard to the antioxidant defenses of the N. rossii kidney, it was found that levels of antioxidant enzymes were reduced during the first hours of heat stress, contributing to increased lipid peroxidation, whereas N. coriiceps kidneys did not show signs of oxidative damage. The gills of N. rossii exhibited more pronounced oxidative damage in response to heat stress than those of N. coriiceps despite the presence of increasing levels of antioxidants, likely due to tissue hypoxia.

Calculating risk from seafood exposure to persistent organic pollutants continues to be problematic as estimates of exposure from diet require extensive monitoring of fish species and limited assessments of bioavailability from sediments where the contaminants tend to reside. Previous studies in our laboratory utilized a laboratory-based isotope dilution method (IDM) to estimate the bioavailability of DDT [1,1,1-trichloro-2, 2-bis(p-chloro-phenyl)ethane] and its metabolites from sediment to biota from a superfund site on the shelf of the Palos Verdes (PVS) Peninsula in California (USA). Using a biota-sediment accumulation factor (BSAF) derived from IDM and biomagnification factors (BMF) calculated from previous studies as well as seafood-consumption data specific to anglers in the PVS area, we estimated cancer and non-cancer risks for anglers and nursing infants representing sensitive groups. Predicted cancer risks from consumption of White croaker (Genyonemus lineatus) to the 50th and 95th percentile to all shore mode anglers were, respectively, 2×10 -7 and 7×10 -7 , which were similar to field studies using fish concentrations of all DDT isomers and their environmental degradates (ΣDDT) from collected animals. The calculated non-cancer hazard quotient values for the 50th and 95th percentile shore mode anglers consuming White croaker from this study (0.008 and 0.023, respectively) were also of similar magnitude as those obtained from studies based on samples obtained solely from fish. For nursing infants, similar results were also observed. These results indicate that estimates of bioavailability using IDM from sediment could be used accurately to determine risk to ΣDDT in humans from fish consumption., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The present study was conducted to assess the in-vivo activities of certain molecular biomarkers under the impact of phorate exposure. Fish, Channa punctatus (35 ± 3.0 g; 14.5 ± 1.0 cm; Actinopterygii) were subjected to semi-static conditions having 5% (0.0375 mg/L for T1 group) and 10% of 96 h-LC 50 (0.075 mg/L for T2 group) of phorate exposure for 15 and 30 d. The oxidative stress was assessed in terms of superoxide dismutase (SOD) and catalase (CAT) activities. DNA damage was measured as induction of micronuclei (MN) and consequent differential expression of apoptotic genes-tumor suppressor (p53), apoptotic peptidase activating factor-1 (apaf-1) and catalase (cat) in liver and kidney, two major sites of biotransformation in fish, were quantified. Our findings reveal significant (p < 0.001) augmentations in SOD and CAT activities of liver and kidney tissues. MN frequency in erythrocytes of fish also increases significantly (p < 0.05) in a dose- and time-dependent manner. The mRNA level of p53 increased significantly (p < 0.05) in liver at 10% of 96 h-LC 50 of phorate exposure after 30 d suggesting generation of stress due to accumulation of reactive oxygen species (ROS). Eventually, these findings decipher the dual role of ROS in generating genotoxicity as is evident by micronuclei induction and differential regulation of p53, apaf-1 and cat genes during the phorate induced DNA damage and apoptosis in test fish. The experimental inferences drawn on the basis of activities of aforesaid biomarkers shall be helpful in elucidating the possible causes of apoptosis under stressful conditions. Further, this study finds ample application in biomonitoring of phorate polluted aquatic ecosystem., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Mercury (Hg) concentrations and nitrogen (δ 15 N) and carbon (δ 13 C) stable isotopic ratios were measured to assess differences in Hg bioaccumulation in four predatory fish species (Mycteroperca microlepis, Lutjanus campechanus, Caulolatilus microps, and Serioli dumerili) of high commercial and recreational importance in Atlantic waters of the southeastern US. Positive relationships existed between Hg and length, weight, and age, for all species, strongest for M. microlepis and L. campechanus. Intraspecific Hg concentrations also strongly correlated with δ 15 N for all species, and δ 13 C for only L. campechanus, and S. dumerili. Comparisons of stable isotopes between species and their impact on mean Hg concentration were inconclusive. This study is the first to report Hg concentrations for C. microps. The current study provides data for an under-sampled region, explores how feeding ecology impacts Hg uptake in commonly co-occurring fishes, and raises questions of the importance of sex and reproduction in Hg accumulation for marine fishes., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The environmental quality differences between two groups of reefs in the Veracruz Reef System were evaluated. The North group of reefs is very close to Veracruz, an urban and port zone, whereas the South group is more isolated, with minor anthropogenic disturbances. To prove the hypothesis that the North group is more affected by anthropogenic activities, the concentrations of hydrocarbons in liver, metals and metalloids such as Se, As, Ba, Cd, Hg and V in muscle, and PAH metabolites in bile were evaluated, and related to biomarkers (transcript abundance of cytochrome P4501A, Vitellogenin, and Glutathione-S-transferase) in two species of fish: Haemulon aurolineatum and Ocyurus chysurus. H. aurolineatum presents the highest concentrations for many pollutants, but O. chysurus shows the most significant differences in pollutant concentrations and biomarkers between the two reef groups, suggesting that this species could be used as a sentinel in future studies in the Gulf of Mexico., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Most deep-sea fish have a single visual pigment maximally sensitive at short wavelengths, approximately matching the spectrum of both downwelling sunlight and bioluminescence. However, Malcosteus niger produces far-red bioluminescence and its longwave retinal sensitivity is enhanced by red-shifted visual pigments, a longwave reflecting tapetum and, uniquely, a bacteriochlorophyll-derived photosensitizer. The origin of the photosensitizer, however, remains unclear. We investigated whether the bacteriochlorophyll was produced by endosymbiotic bacteria within unusual structures adjacent to the photoreceptors that had previously been described in this species. However, microscopy, elemental analysis and SYTOX green staining provided no evidence for such localised retinal bacteria, instead the photosensitizer was shown to be distributed throughout the retina. Furthermore, comparison of mRNA from the retina of Malacosteus to that of the closely related Pachystomias microdon (which does not contain a bacterichlorophyll-derived photosensitzer) revealed no genes of bacterial origin that were specifically up-regulated in Malacosteus. Instead up-regulated Malacosteus genes were associated with photosensitivity and may relate to its unique visual ecology and the chlorophyll-based visual system. We also suggest that the unusual longwave-reflecting, astaxanthin-based, tapetum of Malacosteus may protect the retina from the potential cytotoxicity of such a system.

Mercury contamination in the River Beni basin is an important health risk factor, primarily for indigenous communities that live along the river. Among them are the Tacana, living in their original territory with sustainable use of their natural resources, consuming fish, Caiman yacare, and other riverine resources as their main source of protein. To assess mercury exposure to Tacana people, total mercury (THg) was evaluated in the muscle of seven commercial fish, and Caiman yacare (yacare caiman) during 2007 and 2008. THg was extracted by acid digestion and concentrations were determined by atomic absorption spectrometry. Mean mercury concentrations in C. yacare was 0.21 ± 0.22 μg g -1 Hg w.w. (wet weight), which is lower than expected given its high trophic level, and its long life-span. It is possible that mercury in C. yacare is accumulated in other organs, not included in this study; but it is also possible that physiological mechanisms are involved that help caimans get rid of ingested mercury, or simply that C. yacare's diverse diet reduces THg accumulation. Carnivorous fishes (Pygocentrus nattereri, Pseudoplatystoma tigrinum, Zungaro zungaro, Plagioscion squamosissimus, and Leiarius marmoratus) had the highest total mercury concentrations, ranging from 0.35 to 1.27 μg g -1 Hg w.w. moreover, most were above the limit recommended by WHO (0.5 μg g -1 Hg w.w.); except for Leiarius marmuratus, which presented a mean of 0.353 ± 0.322 μg g -1 Hg w.w. The two non-carnivorous fish species (Prochilodus nigricans, and Piaractus brachypomus) present mean concentrations of 0.099 ± 0.027, and 0.041 ± 0.019 μg g -1 Hg w.w., respectively. Finally, recommendations on the consumption habits of Tacana communities are discussed., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Lead (Pb) and calcium (Ca) concentrations were measured in fillet samples of longear sunfish (Lepomis megalotis) and redhorse suckers (Moxostoma spp.) collected in 2005-2012 from the Big River, which drains a historical mining area in southeastern Missouri and where a consumption advisory is in effect due to elevated Pb concentrations in fish. Lead tends to accumulated in Ca-rich tissues such as bone and scale. Concentrations of Pb in fish muscle are typically low, but can become elevated in fillets from Pb-contaminated sites depending in part on how much bone, scale, and skin is included in the sample. We used analysis-of-covariance to normalize Pb concentration to the geometric mean Ca concentration (415 ug/g wet weight, ww), which reduced variation between taxa, sites, and years, as was the number of samples that exceeded Missouri consumption advisory threshold (300 ng/g ww). Concentrations of Pb in 2005-2012 were lower than in the past, especially after Ca-normalization, but the consumption advisory is still warranted because concentrations were >300 ng/g ww in samples of both taxa from contaminated sites. For monitoring purposes, a simple linear regression model is proposed for estimating Ca-normalized Pb concentrations in fillets from Pb:Ca molar ratios as a way of reducing the effects of differing preparation methods on fillet Pb variation.

This study investigated the effects of different environmental factors on (137)Cs uptake in three subtropical estuarine fish, and the trophic transfer of (137)Cs in the fish from different preys. Our data showed that salinity, potassium, and temperature had appreciable effects on the dissolved uptake of (137)Cs in the fish, but no conclusive relationship was found between the effects of salinity and potassium concentration on the uptake. The dietary assimilation of (137)Cs was 51-55% in the omnivorous fish Siganus fuscescens when fed with macroalgae or bivalve tissues, and was much lower than those in carnivorous fish Sebastiscus marmoratus and Jarbua terapon (70-79%). Dietary pathway dominated the (137)Cs accumulation in the omnivorous and carnivorous fish, both of which exhibited strong potential to biomagnify (137)Cs from their preys. Using the biokinetic model, we demonstrated that salinity and temperature only had minor effects on the overall accumulation of (137)Cs in carnivorous species living in estuarine environment. Modeling calculation suggested that it would take 37-80 days for the fish to reach 95% of steady-state concentration, and lower somatic growth increased the time to reach steady-state in the fish., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Cadmium (Cd) is one of the most toxic metals and is widely distributed in freshwater and marine environments. It has received much attention from a toxicological perspective. The aim of this study was to assess the effect of Cd in the peacock blenny Salaria pavo, a species of the family of blennies that was used as bioindicator of water pollution. We performed a sublethal contamination of fish to 2 mg CdCl2 L(-1) during 1, 4, 10, and 15 days. Cd accumulation was measured in gills and liver and displayed a significant increase of its concentration throughout the experiment, with slightly higher levels in the liver, except after 4 days. Partial-length cDNA of mt1, mt2, mnsod, cuznsod, cat, and gpx were characterized. Results from mRNA expression levels displayed an up-regulation of mt2 and mnsod. Biomarker activities were determined in gills and liver. In gills, data displayed an inhibition of EROD and GST activities. Cd exposure significantly increased GPx activities but did not affect CAT levels throughout the experiment. No LPO induction was observed in gills of exposed fish. Regarding the liver, the activity of all enzymes and MDA levels increased significantly from the beginning of the experiment except EROD that increased after 15 days of contamination only. At the histological level, fish exhibited pathological symptoms in gills and liver with a predominance of circulatory disturbances in gills and regressive changes in the liver. Our results displayed that peacock blennies are able to survive Cd toxicity due to various physiological adaptation mechanisms.

Knowledge on multi-stressors effects required for environmental and human risk assessments is still limited. This study investigated the combined effects of gold nanoparticles (Au-NP), microplastics (MP) and temperature increase on Pomatoschistus microps, an important prey for several higher level predators, including some species edible to humans. Four null hypotheses were tested: H01: P. microps juveniles do not take up Au-NP through the water; H02: Au-NP (ppb range) are not toxic to juveniles; H03: the presence of MP do not influence the effects of Au-NP on juveniles; H04: temperature increase (20-25°C) does not change the effects of the tested chemicals on juveniles. Wild juveniles were acclimated to laboratory conditions. Then, they were exposed to Au-NP (≈5nm diameter) and MP (polyethylene spheres, 1-5μm diameter), alone and in mixture, at 20°C and 25°C, in semi-static conditions. After 96h of exposure to Au-NP, fish had gold in their body (0.129-0.546μg/g w.w.) leading to H01 refusal. Exposure to Au-NP alone caused a predatory performance decrease (≈-39%, p<0.05) leading to H02 refusal. MP did not change the Au-NP toxicity leading to H03 acceptance. Temperature rise significantly increased the concentration of gold in fish exposed to Au-NP (≈2.3 fold), and interacted with chemical effects (e.g. glutathione S-transferases activity) leading to H04 refusal. Thus, the results of this study highlight the importance of further investigating the effects of multi-stressors on marine fish, particularly the effects of temperature on the uptake, biotransformation, elimination and effects of nanoparticles and microplastics, either alone or in mixture. This knowledge is most important to improve the basis for environmental and human risk assessments of these environmental contaminants of high concern., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Concentrations of V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Cd and Pb were determined in muscle, liver and gonads of two ecologically contrasting fishes, Helicolenus dactylopterus (benthic) and Pagellus bogaraveo (benthopelagic). Elevated concentrations of As, Se and Cd found in tissues of both species appear to mirror the contribution of volcanic activity to the natural inputs of elements to Azorean waters. Results showed different element accumulation between the two species. Whereas higher concentrations were found in the liver of P. bogaraveo, elevated values were observed in the muscle of H. dactylopterus. Differences in accumulation are most likely related to metabolic rates, diet specificities and habitat. Concentrations in gonads varied up to four orders of magnitude, being higher and more variable in P. bogaraveo than H. dactylopterus. Elevated values of Cd were detected in gonads of both species despite its non-essential role on metabolic functions, presumably related to elimination., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Leptin is a hormone produced by fat cells that regulates the amount of fat stored in the body and conveys nutritional status to the reproductive axis in mammals. In the present study we identified two subtypes of leptin genes (lepa and lepb) and a leptin receptor gene (lepr) from chub mackerel (Scomber japonicus) and there gene expression under different feeding conditions (control and high-feed) and pubertal development stages was analyzed using quantitative real-time PCR. The protein lengths of LepA, LepB and LepR were 161 amino acids (aa), 163 aa and 1149 aa, respectively and both leptin subtypes shared only 15% similarity in aa sequences. In pubertal females, lepa was expressed in the brain, pituitary gland, liver, adipose tissue and ovary; however, in adult (gonadal maturation after the second in the life) females, lepa was expressed only in the liver. lepb was expressed primarily in the brain of all fish tested and was expressed strongly in the adipose tissue of adults. lepr was characterized by expression in the pituitary. The high-feed group showed a high conditioning factor level; unexpectedly, hepatic lepa and brain lepr were significantly more weakly expressed compared with the control-feed group. Furthermore, the expression levels of lepa, lepb and lepr genes showed no significant differences between pre-pubertal and post-pubertal fish. On the other hand, pituitary fshβ and lhβ showed no significant differences between different feeding groups of pre-pubertal fish. In contrast, fshβ and lhβ expressed abundantly in the post-pubertal fish of control feed group. Based on these results, whether leptin plays an important role in the nutritional status and pubertal onset of chub mackerel remains unknown., (Copyright © 2015 Elsevier Inc. All rights reserved.)

In recent years, brain kisspeptin system has been shown to be involved in diverse reproductive function, including sexual differentiation in vertebrates. Our previous reports demonstrated that the chub mackerel (Scomber japonicus) brain expresses two kisspeptin (kiss1, kiss2), two kisspeptin receptor (kissr1, kissr2) and three gonadotropin-releasing hormone (gnrh1, gnrh2, gnrh3) genes. In the present study, using quantitative real-time PCR (qRT-PCR) assays, we analysed expression changes of these genes during early development (0-30dphs) and gonadal sex differentiation periods (37-60dphs). Absolute expression level of kiss-kissr-gnrh in the whole head was higher between 0 and 15dphs, in comparison to later developmental periods. Histological analyses revealed presence of sexually differentiated males and females with testicular and ovarian features at 37, 45, and 60dphs. In both males and females, kiss2, kissr1, and kissr2 levels were higher at 37dph, in comparison to 45 and 60dphs, with kiss1 showing no significant differences. Levels of all three gnrh mRNAs were higher at 45dph, in comparison to 60dph. Changes in the expression level of kiss-kissr-gnrh mRNAs in different brain regions of sexually differentiated males and females indicated differences in their regional distribution. These results suggest possible involvement of Kiss-KissR-GnRH systems during early development and gonadal sex differentiation in the chub mackerel., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Total mercury concentrations were determined by atomic absorption spectrometry in muscle tissue of two commercially important species of carnivorous fishes croaker (Micropogonias furnieri) and cutlassfish (Trichiurus lepturus) caught in Itaipu estuary, Rio de Janeiro. In this study, whitemouth croaker presented more mercury than Atlantic cutlassfish. Bioaccumulation differences can be explained by the biological behavior of juveniles whitemouth croaker, that remain in the estuary up to maturity, which makes them good indicators of local environmental impacts (0.110 mg Kg(-1) HgT). It also can be explained by differences in nutritional requirements between the different life stages of two species. The analysis showed the presence of low levels of the metal. However, our results suggest a possible risk to human health, depending on the level of fish consumption.

This 3 × 3 factorial study assessed pyrethroids, carbamates and neonicotenoids groups of pesticides in replicated samples of three fish species from low (S1, reference), medium (S2) and heavy (S3) polluted sites receiving agricultural run-offs around the Indus River. Water and sediment samples from the same sites were also analysed for these pesticides by using high-performance liquid chromatography. Out of nine investigated pesticides, only three pesticides (deltamethrin, carbofuran and cypermethrin) were detected in fish and sediment samples. Deltamethrin in Cyprinus carpio ranged from 0.490 to 0.839 μg/g, mostly exceeding 0.5 μg/g as the maximum residual limit suggested by FAO-WHO, whereas it ranged from 0.214 to 0.318 μg/g in the sampled sediments. The carbofuran concentrations were 0.0425-0.066 and 0.613-0.946 μg/g in Labeo rohita and Channa marulius muscles respectively and 0.069-0.081 μg/g in the corresponding sediment samples. These values were either higher or lower than the maximum limit (0.1 μg/g) as suggested by FAO-WHO. Conversely, the cypermethrin concentration ranged from 0.141 to 0.174 in Ch. marulius and 0.183-0.197 μg/g in sediments which were both below the FAO-WHO maximum limit of 2 μg/g. No pesticide residues were detected in water from these sampling sites. Most selected physicochemical variables were within the acceptable range of World Health Organization for the water quality for aquatic life. The detected pesticide contents were mostly higher in fish muscles from heavily polluted sites. This is worrying because these pesticides may pose health risks for the fish and people of the study area. However, a preliminary risk assessment indicated that the calculated daily intake of detected pesticides by people consuming fish from the Indus River was low and did not present an immediate risk to the fish-consuming people. This study may be used as a benchmark to determine the safety of fish meat in order to develop intervention strategies to maintain the water quality and to protect the health of fish and fish-consuming people.

The aim of this study was to determine the concentrations of Al, As, B, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sr, and Zn in liver, gills, gonads, and brain of four ecologically different fish species in Serbia: piscivorous northern pike, benthivorous sterlet and silver bream, and omnivorous common carp. Fish were caught at four sites along the stretch of the River Tisza in the Pannonian part of Serbia during October 2010. Results revealed that heavy metals and microelements with the highest values in fish samples were Fe, Al, and Zn. The highest concentration of heavy metals and microelements was recorded in omnivorous common carp, and organs that most intensively accumulated the greatest number of metals were liver and gills, whereas the locality did not exert a marked impact on level of bioaccumulation.

Water quality of the Jansen Lagoon (São Luís, Maranhão State, Brazil) was assessed through histological biomarkers and microbiological parameters. To this end, 29 fish specimens (11 Centropomus undecimalis and 18 Sardinella sp) and eight water samples were collected during the rainy and dry periods of 2013. The lagoon water showed thermotolerant coliform indices above the limit set forth in CONAMA Resolution 357/2005. Histological changes observed in the gills were: lifting of the respiratory epithelium, hyperplasia of the lamellar epithelium, incomplete and complete fusion of several lamellae, disorganization of the lamellae, congestion of blood vessels, aneurysms, hypertrophy of the respiratory epithelium, hemorrhage and rupture of the lamellar epithelium and parasite. The histological alteration index (HAI) average value to Sardinella sp was 31.8 and to C. undecimalis was 22.2. The average HAI value in both species corresponds to category 21-50, with tissue injuries being classified from moderate to severe. The presence of histological injuries and the HAI values indicate that the fish sampled from the Jansen Lagoon are reacting to non-specific xenobiotics present at the site.

Estuaries are globally important areas for methylmercury bioaccumulation because of high methylmercury production rates and use by fish and wildlife. We measured total mercury (THg) concentrations in ten fish species from 32 wetland and open bay sites in San Francisco Bay Estuary (2005-2008). Fish THg concentrations (μg/g dry weight ± standard error) differed by up to 7.4× among estuary habitats. Concentrations were lowest in open bay (0.17 ± 0.02) and tidal wetlands (0.42 ± 0.02), and highest in managed seasonal saline wetlands (1.27 ± 0.05) and decommissioned high salinity salt ponds (1.14 ± 0.07). Mercury also differed among fishes, with Mississippi silversides (0.87 ± 0.03) having the highest and longjaw mudsuckers (0.37 ± 0.01) the lowest concentrations. Overall, 26% and 12% of fish exceeded toxicity benchmarks for fish (0.20 μg/g wet weight) and piscivorous bird (0.30 μg/g wet weight) health, respectively. Our results suggest that despite managed wetlands' limited abundance within estuaries, they may be disproportionately important habitats of Hg risk to coastal wildlife., (Published by Elsevier Ltd.)

Polychlorinated biphenyls (PCBs) and hexachlorocyclohexanes (HCHs) were analyzed in surface sediments (<30 cm depth) and two fish species: Nile perch (Lates niloticus) and Nile tilapia (Oreochromis niloticus). The samples were collected from the Napoleon Gulf on the northern shore of Lake Victoria. The analysis was done using a gas chromatograph (GC) coupled to a high resolution mass spectrometer for PCBs and a GC equipped with an electron capture detector for HCHs. Total (Σ) PCBs in the muscles of fish varied widely with mean values ranging from 41 to 670 pg g(-1) lipid weight (lw). The PCB levels in L. niloticus were significantly greater than those in O. niloticus. The large variability observed in the data was attributed to differences in feeding habits and trophic levels. While O. niloticus is a filter-eating fish species feeding mainly on phytoplankton and zooplankton, L. niloticus have predatory feeding behaviors and prefer a diet of live fish and, therefore, are more prone to bio-accumulate contaminants. The mean PCB concentrations in the sediments varied from 362 to 848 pg g(-1) dry weight. Variations in PCB levels were observed from one study site to another, this was attributed to the nature and particle size of the sediments. HCH isomers were detected in fish at mean concentrations of up to 45,900 pg g(-1) lw. The PCB and HCH concentrations were lower than those from previous studies elsewhere in literature and were below the maximum residue limits set by the European Commission and FAO/WHO Codex Alimentarius Commission, implying that the fish was fit for human consumption., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The contamination of the Gironde Estuary, southwest of France, by polychlorinated biphenyls (PCBs) was assessed using six fish of high ecological and economic importance as bioindicator species. The concentrations of 21 PCB congeners and total fat contents were determined in the muscle and liver of eels (Anguilla anguilla), seabass (Dicentrarchus labrax), flounders (Platichthys flesus), meagres (Argyrosomus regius), mullets (Liza ramada), and soles (Solea vulgaris). In addition, information regarding the trophic ecology of the studied fish was obtained through the analysis of carbon and nitrogen stable isotopes (i.e., δ(13)C and δ(15)N) in muscle. Results revealed high PCB concentrations in fish compared to monitored European estuaries. The muscle of eels was by far the most contaminated fish flesh (Σ7PCBs=1000±440 ng g(-1) on a dry weight basis), while the higher PCB concentrations in liver were measured in flounder (Σ7PCBs=2040±1160 ng g(-1) d.w.). A quantile regression approach allowed to investigate the fate of PCBs in the Gironde estuarine fish assemblage, and revealed a general process of trophic magnification. Finally, most of the analysed fish presented PCB concentrations in muscle meat above the current European maximum limits for sea products, while the derived "Toxic Equivalent Quantity" (TEQ) revealed human health concerns only for high-fat fish consumption., (Copyright © 2014. Published by Elsevier Ltd.)

Pikeperch (Sander lucioperca), European catfish (Silurus glanis), burbot (Lota lota), and common carp (Cyprinus carpio) were collected from the Danube River (Belgrade section, Serbia), and samples of liver, muscle, and gills were analyzed for Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, Pb, Se, Sr, and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES) to highlight the importance of species and tissue selection in monitoring research, contaminant studies, and human health research. The Kruskal-Wallis test revealed significant differences between fish species in regard to metal levels in liver, muscle, and gills. The principal component analysis (PCA) indicated that the studied fish species could be grouped on the basis of the level of analyzed elements in liver and gills. The Mann-Whitney test showed two subsets (one comprising two piscivorous species, pikeperch and catfish, and the other, two polyphagous species, burbot and carp) in regard to Cr and Hg levels in liver (higher levels in piscivorous species), as well as B, Fe, and Hg in gills (B and Fe with higher levels in polyphagous and Hg in piscivorous species), and As in muscle (higher levels in polyphagous species). Carp had distinctly higher levels of Cd, Cu, and Zn in liver in comparison to other three species. None of the elements exceeded the maximum acceptable concentrations (MAC). However, since Hg levels are close to the prescribed MAC levels, the consumption of these fishes can be potentially hazardous for humans., (© 2013 Elsevier Inc. All rights reserved.)

In order to investigate bioaccumulation of mercury in Iranian coastal waters fish, tiger tooth croaker (Otolithes ruber) and yellowspotted trevally (Carangoides fulvoguttatus) from the Gulf of Oman and grass carp (Ctenopharyngodon idella) and silver carp (Hypophthalmichthys molitrix) from Zabol Chahnimeh reservoirs were sampled in May 2012. In these ecosystems, total mercury concentrations were measured in muscle and gill of these four fish species. Both regions did not reveal a significant difference. In H. molitrix and O. ruber, mercury concentrations in gill increased with increasing length (H. molitrix, r = 0.94, p < 0.005; O. ruber, r = 0.94, p > 0.005) and weight (H. molitrix, r = 0.94, p < 0.005; O. ruber, r = 0.82, p > 0.04). Generally, mercury levels in the analysed fish samples were higher than WHO, FDA and US-EPA legal limits.

We performed dynamic linear modeling analysis on fish contaminant data collected from the Ontario Ministry of the Environment and Environment Canada to examine long-term trends of total mercury (THg) and polychlorinated biphenyls (PCBs) in Lake Erie. Several sport fish species (walleye, smallmouth bass, rainbow trout) with differences in their diet habits, food competition strategies and foraging patterns are characterized by weakly increasing trends of their THg levels in Lake Erie after the mid- or late 1990s. Similarly, our analysis shows that the decline rates of the PCB body burdens in white bass, smallmouth bass, freshwater drum and whitefish have slowed down or have switched to weakly increasing rates over the last decade. Our analysis also provides evidence that the rainbow trout and coho salmon PCB concentrations have been decreasing steadily but the associated rates were fairly weak. The systematic shifts in energy trophodynamics along with the food web alterations induced from the introduction of non-native species, the new role of the sediments as a net contaminant source, and the potentially significant fluxes from the atmosphere stand out as some of the hypotheses proposed to explain the limited Lake Erie response in recent years to the various contamination mitigation strategies., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The aim of the present study was to examine the species-specific stress response for seven Mediterranean fishes in culture. Also, to evaluate the method of measuring free cortisol concentration in the rearing water as a non-invasive and reliable indicator of stress in marine species, of aquaculture importance. Gilthead sea bream, Sparus aurata (Sparidae); common dentex, Dentex dentex (Sparidae); common Pandora, Pagellus erythrinus (Sparidae); sharpsnout sea bream, Diplodus puntazzo (Sparidae); dusky grouper, Epinephelus marginatus (Serranidae); meagre, Argyrosomus regius (Sciaenidae) and European sea bass, Dicentrarchus labrax (Moronidae) were subjected to identical acute stress (5-6 min chasing and 1-1.5 min air exposure) under the same environmental conditions and samples were analyzed by the same procedures. Results indicated that there was a clear species-specificity in the magnitude, timing and duration of the stress response in terms of cortisol, glucose and lactate. European sea bass showed a very high response and dusky grouper and meagre a very low response, except plasma glucose concentrations of dusky grouper which was constantly high, while sharpsnout sea bream presented a protracted stress response, up to 8h. The present study confirmed that free cortisol release rate into the water can be used as a reliable stress indicator., (Copyright © 2011 Elsevier Inc. All rights reserved.)

This study was performed to investigate the metal concentrations in muscle, liver, gonad, and gill of gilthead seabream (Sparus aurata L., 1758), European seabass (Dicentrarchus labrax L., 1758), and keeled mullet (Liza carinata Valenciennes, 1836) from Yelkoma Lagoon, northeastern Mediterranean region. So, the levels of cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, and zinc in tissues of specimens from the lagoon were determined by inductively coupled plasma optical emission spectrometer. Concentrations of metals in muscles of the examined species ranged from 0.10 to 0.47 mg kg(-1) for cadmium, 0.10 to 0.43 mg kg(-1) for cobalt, 0.17 to 0.72 mg kg(-1) for chromium, 0.62 to 1.03 mg kg(-1) for copper, 28.9 to 52.3 mg kg(-1) for iron, 0.75 to 0.96 mg kg(-1) for manganese, 0.11 to 0.57 mg kg(-1) for nickel, 0.19 to 0.47 mg kg(-1) for lead, and 6.01 to 13.9 mg kg(-1) for zinc, respectively. Additionally, metal concentrations in muscles of fish were assessed for human uses according to provisional tolerable weekly intake and provisional tolerable daily intake.

In the San Francisco Estuary, management actions including tidal marsh restoration could change fish mercury (Hg) concentrations. From 2005 to 2007, small forage fish were collected and analyzed to identify spatial and interannual variation in biotic methylmercury (MeHg) exposure. The average whole body total Hg concentration was 0.052 microg g(-1) (wet-weight) for 457 composite samples representing 13 fish species. MeHg constituted 94% of total Hg. At a given length, Hg concentrations were higher in nearshore mudflat and wetland species (Clevelandia ios, Menidia audens, and Ilypnus gilberti), compared to species that move offshore (e.g., Atherinops affinis and Lepidogobius lepidus). Gut content analysis indicated similar diets between Atherinops affinis and Menidia audens, when sampled at the same locations. Hg concentrations were higher in sites closest to the Guadalupe River, which drains a watershed impacted by historic Hg mining. Results demonstrate that despite differences among years and fish species, nearshore forage fish exhibit consistent Hg spatial gradients., (Copyright 2010 Elsevier Ltd. All rights reserved.)

A fast and simple method for the analysis of polybrominated diphenyl ethers (PBDEs) in fish samples was developed using a one-step extraction and clean-up by means of pressurized liquid extraction (PLE) combined with gas chromatography-ion trap tandem mass spectrometry (GC-ITMS-MS). The selective PLE method provided to obtain ready-to-analyse extracts without any additional clean-up step, using a sorbent as fat retainer inside the PLE cell. Several PLE operating conditions, such as solvent type, extraction temperature and time, number of cycles and type of fat retainer, were studied. Using Florisil as fat retainer, maximum recoveries of PBDEs (83-108%) with minimum presence of matrix-interfering compounds were obtained using a mixture of n-hexane:dichloromethane 90:10 (v/v) as solvent, an extraction temperature of 100 degrees C and a static extraction time of 5 min in combination with three static cycles. Quality parameters of the method were established using standards and fish samples. Limits of detection and quantification ranged from 10 to 34 pg g(-1) wet weight and between 34 and 68 pg g(-1) wet weight, respectively. In addition, good linearity (between 1 and 500 ng ml(-1)) and high precision (RSD %<15%) were achieved. The method was validated using the standard reference material SRM-1945 (whale blubber) and was then applied to the analysis of PBDEs in fish samples.

In this study, concentrations of 16 elements were quantified in muscles and livers of 141 fishes belonging to five commercially species. It was also our intention to evaluate potential risks to human health associated with seafood consumption. The grunt, flathead, greasy grouper, tiger-tooth croaker and silver pomfret fish species were obtained from Abadan, Deylam, Bushehr-Nirogah, Dayyer port, Lengeh port and Abbas port in Hormozgan, Bushehr and Khozesran provinces at the Iranian waters of the Persian Gulf. The contents of Al, As, Be, Cd, Cr, Co, Cu, Fe, Pb, Mn, Mo, Ni, Sb, Tl, V and Zn in fish muscles and livers were determined by Inductively Coupled Plasma Mass Spectrometry (ICP MS), after digestion in a CEM (Mars 5) microwave oven using nitric acid and hydrogen peroxide. Our results indicated that almost all metals were more accumulated in younger flathead, greasy grouper and tiger-tooth fishes. Contrary to the other fish species, grunt seems to stronger accumulating elements in the older fishes. Strong and positive correlations were observed in three or more of the fish species between V, Al, Fe, Tl, Co and Pb. The results confirmed that fish muscle and liver tissues appeared to be good bio-indicators for identification of coastal areas exposed to metallic contaminants. The results also showed that the element levels in the muscles of all fishes in our study were lower than the maximum allowable concentrations and pose no threat to public health, except for arsenic.

Polybrominated diphenyl ethers (PBDEs) concentrations and congener profiles were evaluated in four species of Antarctic fish (Chionodraco hamatus, Chaempsocephalus gunnari, Gymnoscopelus nicholsi,Trematomus eulepidotes) and in one Mediterranean species (Tuna, Thunnus thynnus). The GC/MS-ECNI analysis revealed that average sigmaPBDE concentrations in Antarctic fish species ranged from 0.09 ng g(-1)wet weight (wet wt) in G. nicholsi to 0.44 ng g(-1)wet wt in C. gunnari. In Mediterranean tuna they were two or three orders of magnitude higher (15 ng g(-1)wet wt). The PBDE congener profiles differed between species; low brominated congeners prevailed in Antarctic species while in tuna tetra- and pentabromodiphenyl ethers were the most abundant congener groups (41% and 44%, respectively). These results showed that PBDE levels significantly correlated with the length of the fishes (r(2)=0.85, p<0.01) in C. hamatus, but not with the weight of the fish. Moreover, mean sigmaPBDE concentrations in tuna were statistically higher in females than in males (18 and 13 ng g(-1)wet wt, respectively; p<0.05), which was explained by the lower fat contents of the males that just had entered the spawning period. The results of this study confirm that PBDE contamination of the marine environment now occurs on a global scale.

Whole Atlantic mackerel (Scomber scombrus), sardine (Sardina pilchardus) and Mediterranean hake (Merluccius merluccius) from the Croatian Adriatic were stored at 22 degrees C and changes in histamine, putrescine, tyramine and cadaverine levels were monitored in relation to bacterial endotoxin. After 12 h, histamine levels in sardine were above the legal limit of 50 mg kg(-1), set by the US Food and Drug Administration, and an increase in putrescine content preceded the increase in histamine. After 24 h, histamine contents in mackerel and sardine reached 1090 +/- 101 and 577 +/- 275 mg kg(-1), respectively, which exceeded the toxic threshold of 500 mg kg(-1). At the same time, the putrescine content was also high in both fish (353-420 mg kg(-1)). The time-course of endotoxin production was similar in all fish species stored at 22 degrees C. A high correlation was found between endotoxin and histamine, and between endotoxin and putrescine in mackerel and sardine. On the other hand, high endotoxin levels in hake, after 24 h, were associated with the low histamine and putrescine content (40-60 mg kg(-1)).

The focus of this research was to develop a model based solely on molecular descriptors capable of predicting fish bioconcentration factors (BCF). A fish BCF database was developed from high-quality, regulatory agency reviewed studies for pesticides based on the same laboratory protocol and the same fish species, Lepomis macrochirus. A commercially available software program was used to create a quantitative structure-activity relationship (QSAR) from 93 BCF studies based on unique molecules. An additional 16 molecules were used to test the accuracy of QSAR model predictions for a variety of pesticide classes. Regression of the measured versus predicted log BCF values yielded a regression coefficient of 0.88 for the validation data set. On the basis of the results from this research, the ability to predict BCF by a QSAR regression model is improved using a fully structurally derived model based solely on structural data such as the number of atoms for a given group (e.g., -CH3) or the local topology of each atom as derived from electron counts. Such descriptors provide insightful information on a molecule's potential BCF behavior in aquatic systems.

Fish with different ecological needs were captured from the northeast Mediterranean Sea to determine metallothioneinlike proteins in their livers. Heat-treated liver samples were run on a column packed with Sephadex G-75 (Sigma, Germany) for subsequent determination of metals, sulfhydryl, and absorbance at 254 and 280 nm. Liver cytosols of Sparus auratus and Mullus barbatus had three heat-stable protein peaks, whereas Mugil cephalus and Atherina hepsetus had two. The third protein peak, containing metallothionein-like proteins (5000 to 6000 Da), was present in all fish. Only high- and low-molecular-weight proteins contained sulfhydryl and metals. Zinc was the most abundant metal in the metallothioneinlike proteins, whereas cadmium and lead were not detected. The differences in the characteristics of metal-binding proteins among fish indicate that the biological characteristics of fish species should be carefully taken into account concerning natural monitoring studies.

Total mercury levels were measured in largemouth bass (Micropterus salmoides), "sunfish" (Lepomis spp.), and "catfish" (primarily Ameiurus spp. and Ictalurus punctatus) from 1971 to 2004 in the middle Savannah River (river km 191 to 302), which drains the coastal plain of the southeastern U.S. Total mercury concentrations were higher in largemouth bass (overall mean of 0.55 mg/kg from 1971 to 2004), a piscivorous (trophic level 4) species than in the other taxa (means of 0.22-0.26 mg/kg), but temporal trends were generally similar among taxa. Mercury levels were highest in 1971 but declined over the next 10 years due to the mitigation of point source industrial pollution. Mercury levels in fish began to increase in the 1980s as a likely consequence of mercury inputs from tributaries and associated wetlands where mercury concentrations were significantly elevated in water and fish. Mercury levels in Savannah River fish decreased sharply in 2001-2003 coincident with a severe drought in the Savannah River basin, but returned to previous levels in 2004 with the resumption of normal precipitation. Regression models showed that mercury levels in fish changed significantly over time and were affected by river discharge. Mercury levels in Savannah River fish were only slightly lower in 2004 (0.3 to 0.8 mg/kg) than in 1971 (0.4 to 1.0 mg/kg) despite temporal changes during the intervening years.

The objective of this study was to evaluate potential human and ecological risks associated with metals in fish and crayfish from mining in the Tri-States Mining District (TSMD). Crayfish (Orconectes spp.) and fish of six frequently consumed species (common carp, Cyprinus carpio; channel catfish, Ictalurus punctatus; flathead catfish, Pylodictis olivaris; largemouth bass, Micropterus salmoides; spotted bass, M. punctulatus; and white crappie, Pomoxis annularis) were collected in 2001--2002 from the Oklahoma waters of the Spring River (SR) and Neosho River (NR), which drain the TSMD. Samples from a mining-contaminated site in eastern Missouri and from reference sites were also analyzed. Individual fish were prepared for human consumption in the manner used locally by Native Americans (headed, eviscerated, and scaled) and analyzed for lead, cadmium, and zinc. Whole crayfish were analyzed as composite samples of 5--60 animals. Metals concentrations were typically higher in samples from sites most heavily affected by mining and lowest in reference samples. Within the TSMD, most metals concentrations were higher at sites on the SR than on the NR and were typically highest in common carp and crayfish than in other taxa. Higher concentrations and greater risk were associated with fish and crayfish from heavily contaminated SR tributaries than the SR or NR mainstems. Based on the results of this and previous studies, the human consumption of carp and crayfish could be restricted based on current criteria for lead, cadmium, and zinc, and the consumption of channel catfish could be restricted due to lead. Metals concentrations were uniformly low in Micropterus spp. and crappie and would not warrant restriction, however. Some risk to carnivorous avian wildlife from lead and zinc in TSMD fish and invertebrates was also indicated, as was risk to the fish themselves. Overall, the wildlife assessment is consistent with previously reported biological effects attributed to metals from the TSMD. The results demonstrate the potential for adverse effects in fish, wildlife, and humans and indicate that further investigation of human health and ecological risks, to include additional exposure pathways and endpoints, is warranted.

We began monitoring concentrations of both total mercury (THg) and methylmercury (MeHg) in surface water at Stormwater Treatment Area-2 (STA) on July 20, 2000. This 2602 hectare STA was constructed with three independent marshes to remove phosphorus from agricultural runoff and reduce eutrophication in the northern Everglades. However, there was concern that in doing so, STA-2 might inadvertently worsen the existing mercury problem in the Everglades. Accordingly, operating permits stipulated that flow-through operation of these treatment cells could not begin until concentrations of THg and MeHg in the interior marsh were not significantly greater than corresponding concentrations in the supply canal. Cells 2 and 3 quickly met the start-up criteria in the fall of 2000. In contrast, Cell 1 exhibited anomalously high MeHg concentrations in the fall of 2000 and 2001, and the summer of 2002. During the last such event, water-column concentrations in Cell 1 reached 32 ng THg/L and an unprecedented 20 ng MeHg/L. Tissue Hg in resident fishes reached levels as high as 430 ng/g in mosquitofish, Gambusia holbrooki, 930 ng/g in sunfish, Lepomis spp., and 2000 ng/g in largemouth bass, Micropterus salmoides. Guided by results from the monitoring program, flow rate and water depth were managed as a means to alter sulfur biogeochemistry and, thereby, reduce in situ mercury methylation. This adaptive management strategy likely played a role in the decline in water-column concentrations of THg and MeHg in Cell 1 by late 2002 and the subsequent declines in tissue Hg levels in resident fishes. Cell 1 finally met formal start-up criteria on November 26, 2002.

The objective of this study was to determine the current levels of total mercury and methylmercury in the muscle tissues of different fish species caught in the Mediterranean Sea to ascertain whether these concentrations exceed the maximum level stipulated by the European Commission Decision. Total mercury concentrations in the muscles of skates ranged from 0.18 to 1.85 mg/kg (wet weight) (average, 1.00 mg/kg) while levels of 0.11 to 1.92 mg/kg (wet weight) (average, 0.70 mg/kg) and 0.21 to 1.74 mg/kg (wet weight) (average, 0.70 mg/kg) were recorded for blue whiting and red mullet, respectively. For 66.7% of long nose skate samples, 61.4% of thornback ray samples, 42.8% of winter skate samples, and 38% of starry ray samples, the total mercury concentrations exceeded the prescribed legal limit (1.0 mg/kg [wet weight]). Concentrations exceeding the maximum total mercury level stipulated by the European Commission Decision (0.5 mg/kg [wet weight]) were observed in 63.6 and 40% of blue whiting and striped mullet samples, respectively. Mercury was present in the different species almost completely in the methylated form at 55 to 100%. Weekly intakes were estimated and compared with the provisional tolerable weekly intake recommended by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives.

The purpose of this study was to quantify total mercury concentrations in three species of fish in three lakes of western Maryland: Piney Creek reservoir, Deep Creek Lake, and Lake Habeeb. We measured total mercury concentrations in water from each lake and muscle tissue from 119 fish collected in fall 2000: 15 largemouth bass (Micropterus salmoides), 15 yellow perch (Perca flavescens), and 15 bluegill (Lepomis macrochirus) from the Piney Creek reservoir; 15 largemouth bass, 15 yellow perch, and 14 bluegill from Deep Creek Lake; and 15 largemouth bass and 15 bluegill from Lake Habeeb. Average total mercury concentrations (+/- SD) in surface waters were 0.96 +/- 0.03 ng L(-1) for the Piney Creek reservoir, 0.56 +/- 0.07 ng L(-1) for Deep Creek Lake, and 0.40 +/- 0.05 ng L(-1) for Lake Habeeb. These water quality differences were sometimes reflected in the total mercury concentration in fish muscle tissue. Total mercury concentrations in bluegill (0.05 +/- 0.02 microg g(-1)) and largemouth bass (0.10 +/- 0.03 microg g(-1)) from Lake Habeeb were significantly (p < 0.001) lower than the total mercury concentrations in bluegill and largemouth bass from the Piney Creek reservoir (bluegill: 0.13 +/- 0.04 microg g(-1) and largemouth bass: 0.37 +/- 0.18 microg g(-1)) and Deep Creek Lake (bluegill: 0.11 +/- 0.04 microg g(-1) and largemouth bass: 0.30 +/- 0.09 microg g(-1)). Yellow perch from the Piney Creek reservoir had significantly higher total mercury concentrations than yellow perch from Deep Creek Lake (0.20 +/- 0.08 microg g(-1) versus 0.13 +/- 0.04 microg g(-1)). In contrast, total mercury concentrations in largemouth bass from the Piney Creek reservoir and Deep Creek Lake were not significantly different. With the exception of largemouth bass from Lake Habeeb and yellow perch from Deep Creek Lake, there were relatively strong (r(2) > 0.39-0.79) log-log relationships between the size (weight and length) of the fish and total mercury concentrations in muscle tissue. The largest largemouth bass (> 800 g and > 38 cm) from both Deep Creek Lake and the Piney Creek reservoir had total mercury concentrations that exceeded the consumption advisory of 0.5 microg g(-1) that is used by many states and Canada. In contrast, total mercury concentrations in largemouth bass from Lake Habeeb did not exceed this consumption advisory. Our results suggest that fish consumption advisories are needed for largemouth bass in the Piney Creek reservoir and Deep Creek Lake.

Nuclei (larval stage) and outer parts (adult stage) of fish otoliths from the Taiaro closed lagoon (French Polynesia) and adjacent ocean have been analysed for the C-O isotopic compositions. delta 18O values of the nuclei of both populations indicate that isotopic equilibrium is reached. This implies that the lagoonal fish population has done its complete biological cycle in the lagoon and represents an adaptation in a closed system. delta 18O values of the outer parts show a slight isotopic disequilibrium (< 0.2@1000) interpreted in term of vital effect. All the delta 13C values exhibit a strong isotopic disequilibrium related to metabolic activity.