Distribution of trace elements in the tissues of benthic and pelagic fish from the Kerguelen Islands

Multidisciplinary approach to determine the influence of human pressure on nearshore Antarctic fish

Concentrations of five metals together with hematological and morphological parameters were measured in three coastal fish species collected in two sites of the Antarctic Peninsula. Furthermore, we assessed isotopic niche widths among fish populations to better understand their trophic ecology. Nothotenia coriiceps from Fildes Bay displayed high concentrations of Fe and Cu, while those from South Bay had higher concentrations of Cd. All fish from South Bay had higher Zn levels than specimens from Fildes Bay. Effects such as biomagnification of Fe, increased fish metal levels and niche width expansion of Nothotenia coriiceps and Harpagifer antarcticus could be attributed to suboptimal environmental conditions in Fildes Bay. Our findings suggest that early warning signals in coastal Antarctic fish may be linked to increased metal bioavailability as a result of climate change and increased human pressure.

Trophic and environmental influences on trace element concentrations in Australian fur seals

Trace elements (TE) in living organisms can have detrimental health impacts depending on their concentration. As many TEs are obtained through diet, trophic niche changes associated with the impacts of anthropogenic activities and climate-change may influence exposure to top predators. The Australian fur seal (Arctocephalus pusillus doriferus; AUFS) represents the greatest resident, marine predator biomass in south-eastern Australia. With adult female foraging ranges limited to the continental shelf, their source of TEs is geographically restricted. Plasma, red blood cell and milk samples collected between 1998 and 2022 at Kanowna Island, were analysed for TEs (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sn, V and Zn) using inductively-coupled plasma mass-spectrometry (ICP-MS). Plasma fatty-acid profiles and ocean climate variables were used to investigate trophic and environmental influences, respectively, on TE concentrations. Estimated whole blood concentrations in lactating females were comparable to levels reported in other marine mammals, except for Se and Mn. Correlations between adult tissues were negative for Mn and positive for As, Hg and Sn. Molar Se:Hg were high but within reported levels for pinnipeds. Element concentrations in pup plasma were greater than lactating females for Fe, Mn and Sn indicative of high transplacental transfer while doses of Se and As from milk exceeded tolerable effect levels for humans. Relationships with fatty-acid profiles suggest diet influenced concentrations of Cu, Hg, Mn, Sn, V and Zn in adult plasma. In addition, inter-annual variation in TE concentrations were influenced by broad-scale climate indices, including the Southern Annular Mode and the Southern Oscillation Index, and local conditions associated with the seasonally-active Bonney Upwelling. These findings indicate that TE concentrations in blood and milk of AUFS are and will continue to be affected by anticipated oceanographic changes, mediated by alterations in prey type availability, with potential impacts on the population's health.

Total mercury concentrations in Tasman Sea mesopelagic fish: Exploring biotic and abiotic drivers

Understanding mercury (Hg) concentrations in mesopelagic and mid-trophic fishes is important for assessing Hg accumulation in oceanic ecosystems and higher-order predators. This study measured total Hg (THg) concentrations in the whole body of 16 abundant mesopelagic fish species sampled in two distinct sites within the Tasman Sea. Across all species, total Hg concentrations ranged from 0.02 to 0.48 μg g-1 dry weight (0.01 to 0.15 μg g-1 wet weight). Total Hg concentrations varied with vertical migration patterns, with shallower migrators exhibiting higher THg. Females typically had statistically higher THg concentrations than males. Positive correlations between THg concentration and standard length were observed for some but not all species. At the community level, THg concentrations correlated positively with estimated trophic position and foraging habitat, as inferred by stable isotope values. These findings contribute to our understanding of Hg cycling in oceanic ecosystems and the potential for biomagnification in oceanic top-order predators.

Recent Progress on Physiologically Based Pharmacokinetic (PBPK) Model: A Review Based on Bibliometrics

Physiologically based pharmacokinetic/toxicokinetic (PBPK/PBTK) models are designed to elucidate the mechanism of chemical compound action in organisms based on the physiological, biochemical, anatomical, and thermodynamic properties of organisms. After nearly a century of research and practice, good results have been achieved in the fields of medicine, environmental science, and ecology. However, there is currently a lack of a more systematic review of progress in the main research directions of PBPK models, especially a more comprehensive understanding of the application in aquatic environmental research. In this review, a total of 3974 articles related to PBPK models from 1996 to 24 March 2024 were collected. Then, the main research areas of the PBPK model were categorized based on the keyword co-occurrence maps and cluster maps obtained by CiteSpace. The results showed that research related to medicine is the main application area of PBPK. Four major research directions included in the medical field were "drug assessment", "cross-species prediction", "drug-drug interactions", and "pediatrics and pregnancy drug development", in which "drug assessment" accounted for 55% of the total publication volume. In addition, bibliometric analyses indicated a rapid growth trend in the application in the field of environmental research, especially in predicting the residual levels in organisms and revealing the relationship between internal and external exposure. Despite facing the limitation of insufficient species-specific parameters, the PBPK model is still an effective tool for improving the understanding of chemical-biological effectiveness and will provide a theoretical basis for accurately assessing potential risks to ecosystems and human health. The combination with the quantitative structure-activity relationship model, Bayesian method, and machine learning technology are potential solutions to the previous research gaps.

De-novo exposure assessment of heavy metals in commercially important fresh and dried seafood: Safe for human consumption

The heavy metals (HMs) in seafood are alarming due to their biomagnification in the food chain. The concentrations of As, Cd, Hg, Pb, Cr, and Ni in both fresh and dried fish were quantified, and the potential exposure and safe intake levels for human consumption were assessed by the European Commission (EC) and the Food Safety Standard Authority of India (FSSAI). HMs concentrations ranged from 0.003 mg/kg (Cr) to 2.08 mg/kg for (As) and 0.007 mg/kg (Hg) to 2.76 mg/kg (As). Cd, Hg, and Pb levels in fresh and dried fish were below the maximum residue limits (MRLs) set by the EC and FSSAI, which were 0.1 mg/kg, 0.5 mg/kg, and 0.3 mg/kg, respectively. Cr and As concentrations were also below the MRLs of 12 mg/kg and 76 mg/kg for aquatic products specified by FSSAI. The concentration of HMs in fresh and dried fish was found in the order of As > Cr > Ni > Pb > Cd > Hg and As > Cd > Cr > Ni > Pb > Hg, while the fresh and dried fishes contained HMs in the following order: E. areolatus > S. longiceps > L.lentjen > S. barracuda > E. affinis > S. javus and DA > DS > DR > DB > DSF. The metal pollution index (MPI) validates seafood is HMs free, while the single (Pi) and Nemerow integrated pollution index (Pnw) indicate that concentrations of Cd and As in fresh and dried fish have exceeded the threshold value. The target hazard quotient (THQ<1), hazard index (HI < 1), and target cancer risk (TCR<10-4) indicate that there are no non-carcinogenic and carcinogenic risks through the consumption of seafood and seafood products collected from the Tuticorin coast and marketed at the domestic and international levels. The preliminary findings emphasize the importance of formulating domestic legislation/government initiatives to promote seafood and its consumption. The attainment of this objective shall be facilitated by examining the levels of persistent organic pollutants (POPs) in seafood and evaluating its potential risk to consumers.

Mercury in Ten Storm-Petrel Populations from the Antarctic to the Subtropics

The oceans become increasingly contaminated as a result of global industrial production and consumer behaviour, and this affects wildlife in areas far removed from sources of pollution. Migratory seabirds such as storm-petrels may forage in areas with different contaminant levels throughout the annual cycle and may show a carry-over of mercury from the winter quarters to the breeding sites. In this study, we compared mercury levels among seven species of storm-petrels breeding on the Antarctic South Shetlands and subantarctic Kerguelen Islands, in temperate waters of the Chatham Islands, New Zealand, and in temperate waters of the Pacific off Mexico. We tested for differences in the level of contamination associated with breeding and inter-breeding distribution and trophic position. We collected inert body feathers and metabolically active blood samples in ten colonies, reflecting long-term (feathers) and short-term (blood) exposures during different periods ranging from early non-breeding (moult) to late breeding. Feathers represent mercury accumulated over the annual cycle between two successive moults. Mercury concentrations in feathers ranged over more than an order of magnitude among species, being lowest in subantarctic Grey-backed Storm-petrels (0.5 μg g-1 dw) and highest in subtropical Leach's Storm-petrels (7.6 μg g-1 dw, i.e. posing a moderate toxicological risk). Among Antarctic Storm-petrels, Black-bellied Storm-petrels had threefold higher values than Wilson's Storm-petrels, and in both species, birds from the South Shetlands (Antarctica) had threefold higher values than birds from Kerguelen (subantarctic Indian Ocean). Blood represents mercury taken up over several weeks, and showed similar trends, being lowest in Grey-backed Storm-petrels from Kerguelen (0.5 μg g-1 dw) and highest in Leach's Storm-petrels (3.6 μg g-1 dw). Among Antarctic storm-petrels, species differences in the blood samples were similar to those in feathers, but site differences were less consistent. Over the breeding season, mercury decreased in blood samples of Antarctic Wilson's Storm-petrels, but did not change in Wilson's Storm-petrels from Kerguelen or in Antarctic Black-bellied Storm-petrels. In summary, we found that mercury concentrations in storm-petrels varied due to the distribution of species and differences in prey choice. Depending on prey choices, Antarctic storm-petrels can have similar mercury concentrations as temperate species. The lowest contamination was observed in subantarctic species and populations. The study shows how seabirds, which accumulate dietary pollutants in their tissues in the breeding and non-breeding seasons, can be used to survey marine pollution. Storm-petrels with their wide distributions and relatively low trophic levels may be especially useful, but more detailed knowledge on their prey choice and distributions is needed.

Antarctic toothfish Dissostichus mawsoni as a bioindicator of trace and rare earth elements in the Southern Ocean

The Antarctic toothfish Dissostichus mawsoni is a Southern Ocean long-lived top predator which is regularly captured on an annual fishery operating in the region. By its biological and ecological characteristics, it is a potential bioindicator for the concentrations of trace and rare earth elements in the Antarctic. As these elements are mainly transferred through the diet and a deficiency or excess of these elements can lead to diverse health problems, it is important to measure their concentrations on the organisms. This study provides, for the first time, the concentration of 27 trace (major essential, minor essential and non-essential) and rare earth elements in the muscle of D. mawsoni captured in three areas of the Amundsen and Dumont D'Urville Seas (Antarctica). Major essential elements had the highest concentrations, with potassium (K) as the most concentrated, and rare earth elements the lowest. Significant differences between areas were found for most of the studied elements. No bioaccumulation nor biomagnification potential was found for the studied elements, with several elements decreasing concentrations towards larger individuals. Decreasing trends are related with the different habitats occupied by D. mawsoni through their life, suggesting that elements' concentrations in the water is determinant for the concentrations in this top predator, and/or there is a dilution effect as the fish grows. Our results also support that Se presents a detoxification potential for Hg in D. mawsoni, but only when Hg concentrations are higher to unhealthy levels. This study supports D. mawsoni as a potential bioindicator for the concentrations of the different trace and rare earth elements in the Southern Ocean, though only when comparing individuals of similar size/age, but also to evaluate annual changes on their concentrations. Furthermore, D. mawsoni can be a good source of major essential elements to humans with concentrations of major essential elements above some of other marine fish worldwide.

Trace elements and δ15N values in micronekton of the south-western Indian Ocean

Trace elements and δ¹⁵N values were analysed in micronekton (crustaceans, fishes and squids) sampled in the south-western Indian Ocean. Myctophids were associated with high concentrations of arsenic at La Pérouse and MAD-Ridge seamounts, and with lead and manganese at MAD-Ridge and in the Mozambique Channel. The difference in cadmium, copper and zinc concentrations between micronekton broad categories reflected differing metabolic and storage processes. When significant, negative relationships were found between micronekton body size and trace element concentrations, which can possibly be attributed to differing metabolic activity in young and old individuals, dietary shifts and/or dilution effect of growth. No relationships were found between trace element concentrations and δ¹⁵N values of micronekton (except cobalt which decreased with increasing δ¹⁵N values), since most trace elements are not biomagnified in food webs due to regulation and excretion processes within organisms. All trace element pairs were positively correlated in fishes suggesting regulation processes.

First report on the burden and distribution of Cu, Zn, Pb, and Cd in the Ocellated icefish (Chionodraco rastrospinosus) of northern Antarctic Peninsula

Understanding the distribution of trace elements in Ocellated icefish (Chionodraco rastrospinosus), one of fish species with lacking hemoglobin from the family Channichthyidae and distributes in a very limited area at the south Scotia Sea, will help understand their physiological composition and conserve this vulnerable population; however, information on this topic is extremely limited. This study examines trace elements (two essential elements, copper [Cu] and zinc [Zn], and two non-essential elements, cadmium [Cd] and lead [Pb]) in C. rastrospinosus and provides for the first time baseline data on elemental distribution in four tissues of C. rastrospinosus in the northern Antarctic Peninsula (NAP). The element concentrations showed the following trends: Zn > Cu > Pb > Cd in muscle and stomach and Zn > Cu > Cd > Pb in intestine and liver. Among all tissues, muscle had the lowest element concentrations. The average Zn level is 70.81 ± 28.91 μg g^-1 dry weight (DW) in C. rastrospinosus muscle, which is higher significantly than average levels of Cu (0.56 ± 0.41 μg g^-1 DW), Pb (0.29 ± 0.33 μg g^-1 DW) and Cd (0.12 ± 0.05 μg g^-1 DW). Zn and Cd concentrations in the stomach and intestines were significantly positively correlated. C. rastrospinosus could be a useful bioindicator for monitoring variability in trace elements dynamics in NAP and the environmental variability in this region.

Concentration and Distribution of Cu, Zn, Pb, and Cd in Mackerel Icefish (Champsocephalus gunnari) in South Georgia, Antarctic, During Winter

Knowledge of the essential and nonessential elements distribution and behavior in Antarctic fish is important for understanding the essentiality and requirements of minerals in the diet of those species, as well as the bioavailability and storage of trace minerals in the tissues of fishes. In this study, the levels of zinc, copper, cadmium, and lead in muscle, intestine, liver, gill, and skin of mackerel icefish Champsocephalus gunnari (Lönnberg, 1905) in South Georgia were determined during winter. The following element concentration ranking was recorded: Zn > Cu > Cd > Pb in the muscle, Zn > Cu > Cd > Pb in the skin, Zn > Cu > Cd > Pb in the intestine, Zn > Cu > Pb > Cd in liver, and Zn > Cu > Cd > Pb in the gill. The concentration of Zn is higher by about two orders of magnitude than that of the other three elements for the tissues. Generally, apart from Cu levels in the liver and Cd levels in the intestine, the correlation of elements in tissues with both size and weight of C. gunnari is not observed. The levels of elements were compared to those reported for C. gunnari in the Kerguelen waters.

Variation Among Species and Populations, and Carry-Over Effects of Winter Exposure on Mercury Accumulation in Small Petrels

Even in areas as remote as the Southern Ocean, marine organisms are exposed to contaminants that arrive through long-range atmospheric transport, such as mercury (Hg), a highly toxic metal. In previous studies in the Southern Ocean, inter-specific differences in Hg contamination in seabirds was generally related to their distribution and trophic position. However, the Blue Petrel (Halobaena caerulea) was a notable exception among small seabirds, with higher Hg levels than expected. In this study, we compared the Hg contamination of Blue Petrels and Thin-billed Prions (Pachyptila belcheri), which both spend the non-breeding season in polar waters, with that of Antarctic Prions (Pachyptila desolata), which spend the winter in subtropical waters. We collected body feathers and blood samples, representing exposure during different time-frames. Hg concentrations in feathers, which reflect contamination throughout the annual cycle, were related to δ13C values, and varied with ocean basin and species. Blue Petrels from breeding colonies in the southeast Pacific Ocean had much higher feather Hg concentrations than expected after accounting for latitude and their low trophic positions. Both Hg concentrations and δ15N in blood samples of Blue Petrels were much lower at the end than at the start of the breeding period, indicating a marked decline in Hg contamination and trophic positions, and the carry-over of Hg burdens between the wintering and breeding periods. Elevated Hg levels may reflect greater reliance on myctophids or foraging in sea-ice environments. Our study underlines that carry-over of Hg concentrations in prey consumed in winter may determine body Hg burdens well into the breeding season.

Carriage of antibiotic resistant bacteria in endangered and declining Australian pinniped pups

The rapid emergence of antimicrobial resistance (AMR) is a major concern for wildlife and ecosystem health globally. Genetic determinants of AMR have become indicators of anthropogenic pollution due to their greater association with humans and rarer presence in environments less affected by humans. The objective of this study was to determine the distribution and frequency of the class 1 integron, a genetic determinant of AMR, in both the faecal microbiome and in Escherichia coli isolated from neonates of three pinniped species. Australian sea lion (Neophoca cinerea), Australian fur seal (Arctocephalus pusillus doriferus) and long-nosed fur seal (Arctocephalus forsteri) pups from eight breeding colonies along the Southern Australian coast were sampled between 2016-2019. DNA from faecal samples (n = 309) and from E. coli (n = 795) isolated from 884 faecal samples were analysed for class 1 integrons using PCRs targeting the conserved integrase gene (intI) and the gene cassette array. Class 1 integrons were detected in A. p. doriferus and N. cinerea pups sampled at seven of the eight breeding colonies investigated in 4.85% of faecal samples (n = 15) and 4.52% of E. coli isolates (n = 36). Integrons were not detected in any A. forsteri samples. DNA sequencing of the class 1 integron gene cassette array identified diverse genes conferring resistance to four antibiotic classes. The relationship between class 1 integron carriage and the concentration of five trace elements and heavy metals was also investigated, finding no significant association. The results of this study add to the growing evidence of the extent to which antimicrobial resistant bacteria are polluting the marine environment. As AMR determinants are frequently associated with bacterial pathogens, their occurrence suggests that these pinniped species are vulnerable to potential health risks. The implications for individual and population health as a consequence of AMR carriage is a critical component of ongoing health investigations.

Metals in tissues of marine fish from the Thermaikos Gulf, Eastern Mediterranean Sea: Detection of changes with trophic level

Concentrations of 27 metals and elements were investigated in the tissues of 28 demersal and pelagic marine fish species from the Eastern Mediterranean Sea. The analysis indicated highest concentrations of accumulation for the majority of elements in the gills, liver, and scales; whereas, lowest assimilation of elements was reported in the muscle. Pelagic fish accumulated higher concentrations of elements than demersal fish. An inverse correlation due to the growth dilution effect was revealed among element concentrations in the gills, liver, muscle, and skin tissues, and fish size. Patterns of biomagnification for Cs solely were recorded in the muscle and patterns of biodilution for most elements were evident in the gills, liver, muscle, and skin tissues. A positive correlation was determined between trophic level and element concentrations in the scales which could not only be associated with fish diet, but also with metal concentrations in the ambient environment and scales size.

Mercury and selenium in squids from the Pacific Ocean and Indian Ocean: The distribution and human health implications

Squids are globally distributed. Hg-contaminated squids may have high risks on humans. With abundant Se (antagonistic effect on Hg), the risks can be reduced. We collected squids around the world (Northwest Pacific Ocean, Southeast Pacific Ocean and Indian Ocean). Concentrations of Hg and Se were region-based and tissue-based. The higher content of Se were, the lower relative Hg levels were. The correlation between Se:Hg and Se was the strongest in the digestive gland. The values of Se:Hg and THQ all confirm that the health risk was lower in samples with higher concentrations of Se. Despite the risk assessment by Se:Hg, BRV and THQ analysis showed no risk when consumed in moderation, the maximum daily intake is provided based on Monte Carlo simulation. In future, when evaluating the risks cause by Hg exposure and providing the recommended daily amount, it may need to concurrent consideration of Se levels.

Bioaccumulation of heavy metals in fish species of Iran: a review

Accumulation of heavy metals (HMs) in fish tissues is an important factor in monitoring the health and safety of aquatic ecosystems. Furthermore, fish are important parts of aquatic food chains and play a significant role in human health. Considering the significant role of fish in the diet of humans and their ability to transfer and biomagnify HMs, it is necessary to determine and study these contaminants in fish tissues, especially in the edible parts of the fish. In addition to the other ecological and economic services of aquatic ecosystems, water bodies, especially the Persian Gulf in the south and the Caspian Sea in the north of Iran, are the main sources of seafood for people in nearby areas, as well as people living farther away who have gained access to seafood due to the extensive trade of aquatic organisms. This study provides an overview of the health conditions of the aquatic ecosystems in Iran by monitoring HM bioaccumulation in fish species. For this purpose, we reviewed, summarized, and evaluated papers published on HM concentrations in fish species from different aquatic ecosystems, including the Persian Gulf, the Caspian Sea, wetlands, rivers, qanats, water reservoirs, lakes, and dams, with emphasis on species habitats, feeding habits, and target organs in accumulation of HMs. Generally, the highest concentrations of HMs were observed in fishes collected from the Persian Gulf, followed by species from the Caspian Sea. Species inhabiting the lower zone of the water column and carnivorous and/or omnivorous species showed the highest levels of HMs. Moreover, liver was the main accumulator organ for HMs.

Accumulation of Trace Metals in Indigenous Fish Species from the Old Brahmaputra River in Bangladesh and Human Health Risk Implications

In this study, accumulation of the top six most toxic trace metals (Arsenic (As), Cadmium (Cd), Chromium (Cr), Mercury (Hg), Nickel (Ni) and Lead (Pb)) were assessed in six indigenous fish species (Barilius barila, Salmostoma acinaces, Gudusia chapra, Labeo bata, Corica soborna, and Sperata aor) collected from the Old Brahmaputra River in Bangladesh. Human health risk associated with these fish consumption was also evaluated. Metals were analyzed in whole body of fish by an atomic absorption spectrometer (AAS). Mean concentrations of metals (μg/g, wet weight) were in the range of As (< 0.02-0.278), Cd (< 0.002-0.005), Cr (0.239-0.761), Hg (0.008-0.057), Ni (< 0.02-0.044), and Pb (< 0.01-0.038). The metal contents varied significantly among the fishes regarding their feeding habits and living habitats. Concentrations of As, Cr, Hg, and Pb were significantly higher in omnivorous species, whereas the benthopelagic species showed significantly higher accumulation of As (p < 0.05). The target hazard quotient (THQ) for noncarcinogenic risk and target cancer risk (TR) for carcinogenic risk were calculated to estimate the probabilities of experiencing these adverse health effects for the fish consumers. Metal-specific THQ values were all below 1 indicating no potential human health risk. Nonetheless, the hazard index (HI) values to estimate the effects from exposure to all metals collectively elucidated chronic noncarcinogenic health risk particularly from G. chapra consumption. The TR values revealed that there was carcinogenic risk from exposure to As through consumption of the fish. This study finally suggests a systematic and continuous monitoring of trace metal contamination in fishes from the river to ensure the fitness of this food item regarding the safety for human health.

Trace metal contamination and species-specific bioaccumulation in the Zhoushan Fishery, northwestern East China Sea

Metal contamination in fishery water may pose a serious threat to aquatic products and human health. In this study, the contents of seven trace metals were assessed in water, sediment, and ten commercially important species (seven fish and three crustaceans) with different trophic guilds, habitat preferences, and motility, collected from the Zhoushan Fishery, northwest East China Sea. In general, the results showed that the concentrations of trace metals in water and sediment were lower than the safety thresholds set by the National Seawater Quality Standard of China and the sediment quality guidelines, except for Cu, As, and Cr in sediment. The high metal concentrations were spatially distributed in the west of the Zhoushan Fishery, which is probably due to the chemical pollution generated from many large international ports and chemical industries in Hangzhou Bay. The metal concentrations in the species were lower than the legislation thresholds established by the Commission Regulation and China National Standard, except for Cd in two crustacean species. However, a health risk assessment indicated that the consumption of the analyzed seafood is safe. However, there is a potential risk to local consumers who prefer crustaceans. From a species-specific bioaccumulation point of view, species in high trophic guilds, benthivores, species with low motility, or those living near the sediment have been found to be most likely to accumulate metals. Our findings could contribute to the understanding of the accumulation tendencies of metals in species of different trophic guilds with varying habitat preferences and motility and provide valuable data to environmental and seafood safety managers.

Trophic ecology drives trace element concentrations in the Antarctic octopod community

Despite the Antarctic Ocean being considered a pristine environment, elevated trace element concentrations have been reported in many marine organisms. The Antarctic Ocean is particularly vulnerable to climate change, which can also affect the bioaccumulation of trace element concentrations in biota. While Antarctic octopods are key components of the regional food webs as prey for a variety of predators (e.g., seals, fish, and seabirds), their contamination state by trace elements remains largely unknown. This study investigated the trace element concentrations in relation to the trophic ecology in Antarctic octopods. Stable isotope values (δ¹³C and δ¹⁵N) and trace element concentrations (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V, and Zn) were measured in eight different species (Adelieledone polymorpha, Pareledone aequipapillae, P. albimaculata, P. aurata, P. charcoti, P. cornuta, P. felix, and P. turqueti) sampled near Elephant Island, close to the Antarctic Peninsula. Stable isotopes of δ¹⁵N varied among species, with significant differences between A. polymorpha and P. aurata suggesting potential niche segregation. Trace element concentrations also differed among species and with sampling depth, which likely reflects their trophic ecology. The data presented in this study provides the first insight into the trace element concentrations for these endemic octopods in this vulnerable habitat and their stable isotope values.

Mercury biomagnification in a Southern Ocean food web

Biomagnification of mercury (Hg) in the Scotia Sea food web of the Southern Ocean was examined using the stable isotope ratios of nitrogen (δ¹⁵N) and carbon (δ¹³C) as proxies for trophic level and feeding habitat, respectively. Total Hg and stable isotopes were measured in samples of particulate organic matter (POM), zooplankton, squid, myctophid fish, notothenioid fish and seabird tissues collected in two years (austral summers 2007/08 and 2016/17). Overall, there was extensive overlap in δ¹³C values across taxonomic groups suggesting similarities in habitats, with the exception of the seabirds, which showed some differences, possibly due to the type of tissue analysed (feathers instead of muscle). δ¹⁵N showed increasing enrichment across groups in the order POM to zooplankton to squid to myctophid fish to notothenioid fish to seabirds. There were significant differences in δ¹⁵N and δ¹³C values among species within taxonomic groups, reflecting inter-specific variation in diet. Hg concentrations increased with trophic level, with the lowest values in POM (0.0005 ± 0.0002 μg g^-1 dw) and highest values in seabirds (3.88 ± 2.41 μg g^-1 in chicks of brown skuas Stercorarius antarcticus). Hg concentrations tended to be lower in 2016/17 than in 2007/08 for mid-trophic level species (squid and fish), but the opposite was found for top predators (i.e. seabirds), which had higher levels in the 2016/17 samples. This may reflect an interannual shift in the Scotia Sea marine food web, caused by the reduced availability of a key prey species, Antarctic krill Euphausia superba. In 2016/17, seabirds would have been forced to feed on higher trophic-level prey, such as myctophids, that have higher Hg burdens. These results suggest that changes in the food web are likely to affect the pathway of mercury to Southern Ocean top predators.

Relationship Between Heavy Metal Accumulation in Fish Muscle and Heavy Metal Resistance Genes in Bacteria Isolated from Fish

Cadmium, cobalt, copper, nickel, and zinc are the most common pollutant heavy metals that can be discharged into the marine environment with different sources. Whiting (Merlangius merlangus) and mullet (Mullus barbatus) were sampled in four seasons in a year to determine Cd, Co, Cu, Ni, and Zn levels in the muscle and to determine heavy metal resistance genes (MRGs) such as copA, czc, and ncc genes in coliform bacteria isolated from the fish. In both species, zinc was the most abundant metal, while Cd and the Co levels were scarce. Co level was significantly higher in summer in mullet than that of whiting (p < 0.001). The most prevalent MRGs was determined as copA (46.2%) followed by czc (35.8%) and ncc (17.9%). Increased Co and Ni level in the muscle significantly affected the presence of ncc gene in bacteria, while the presence of ncc and copA genes was affected by Ni and Cu levels found in the fish muscle. There was a significant positive correlation between Cd level in the muscle and presence of czc and ncc gene in the bacteria (p < 0.029). When the levels of Cu, Zn, and Cd increased in the muscle of the fish, occurrence of MRGs genes was increased significantly (p < 0.0001). A strong positive correlation was found between heavy metal resistance levels in fish and the prevalence of E. coli and coliforms that harbor heavy metal resistance genes which will be a problem in aquaculture, aquatic ecosystem, and public health.

Large-scale survey of lithium concentrations in marine organisms

Trace metals such as Cu, Hg, and Zn have been widely investigated in marine ecotoxicological studies considering their bioaccumulation, transfer along trophic webs, and the risks they pose to ecosystems and human health. Comparatively, Li has received little attention, although this element is increasingly used in the high-tech, ceramics/glass, and medication industries. Here, we report Li concentrations in more than 400 samples, including whole organisms and different organs of bivalves, cephalopods, crustaceans, and fish. We investigated species from three contrasting biogeographic areas, i.e. temperate (Bay of Biscay, northeast Atlantic Ocean), tropical (New Caledonia, Pacific Ocean), and subpolar climates (Kerguelen Islands, southern Indian Ocean), among diverse trophic groups (filter-feeders to meso-predators) and habitats (benthic, demersal, and pelagic). Although Li is homogeneously distributed in the ocean (at 0.18 μg/mL), Li concentrations in soft tissues vary greatly, from 0.01 to 1.20 μg/g dry weight. Multiple correspondence analyses reveal two clusters of high and low Li concentrations. Li distributions in marine organisms appear to be mostly geographically independent, though our results highlight a temperature dependency in fish muscles. Li is consistently bio-reduced through the trophic webs, with filter-feeders showing the highest concentrations and predatory fish the lowest. Strong variations are observed among organs, consistent with the biochemical similarity between Na and Li during transport in the brain and in osmoregulatory organs. Fish gills and kidneys show relatively high Li concentrations (0.26 and 0.15 μg/g, respectively) and fish brains show a large range of Li contents (up to 0.34 μg/g), whereas fish liver and muscles are Li depleted (0.07 ± 0.03 and 0.06 ± 0.08 μg/g, respectively). Altogether, these results provide the first exhaustive baseline for future Li ecotoxicology studies in marine coastal environments.

Antarctic Adélie penguin feathers as bio-indicators of geographic and temporal variations in heavy metal concentrations in their habitats

Seabird feathers are effective indicators of heavy metal contamination. To propose a biological detection method suitable for the long-term monitoring of heavy metals in the Antarctic environment, eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in Adélie penguin feathers from different body parts, years, and molting grounds in the Antarctic were investigated in this study. It is found that the concentrations of heavy metals in the feathers showed differences among the body part of origin. The levels of the eight elements in the abdomen and back feathers were approximately the same, but some elements of them were significantly higher than those in the tail feathers. The Hg and Cd concentrations in the abdomen and back feathers increased from root to tip, regardless of the sampling year or molting ground. Based on a structural analysis of the feathers, Hg and Cd were mainly distributed in the feather vane rather than the shaft. The methylmercury content accounted for 83%-97% of the total mercury content in all feather samples, regardless of location, year, or body part, thereby supporting the assumption that mercury entering the feather was predominantly methylated and indicating that a relatively toxic form of Hg is excreted through the feathers. The heavy metals in feathers from the same molting ground showed significant differences over the sampling years. The average concentrations of As, Cr, Cu, Ni, and Zn increased significantly from 2015 to 2019, whereas those of Cd, Hg, and Pb tended to decrease. The concentrations of the eight elements in Adélie feathers from three molting grounds varied greatly, possibly in relation to their living areas and dietary structures. Feathers from the Ross Sea site had the highest Cd, Cu, Hg, Ni, and Zn concentrations, the highest As and Cr concentrations were detected in feathers from the Zhongshan site, and feathers from the Great Wall site showed higher Pb concentrations than those from the other two sites. This study established a long-term, nondestructive, and efficient method for monitoring heavy metal contamination in the polar environment in the future.

Species-specific bioaccumulation of trace metals among fish species from Xincun Lagoon, South China Sea

Xincun Lagoon is an important fishing area in northern Hainan Island, China. It has long been exposed to pollutants from local sewage, breeding cages and fishing boats, resulting in serious pollution threats to the survival of fish. In this study, we examined the concentrations of seven trace metals (Cu, Pb, Zn, Cd, Hg, As and Cr) in sixteen economic fish species collected from Xincun Lagoon and their exposed environment (water and sediment). The concentrations of Pb and Zn in the water column were higher than the safety threshold stipulated by Chinese legislation, while the contents of all examined metals in the sediment and fish species were lower than the legislative thresholds set by China and international organizations. The contents of trace metals in the fish species in high trophic levels or those that prefer to live in/on the sediment layer were significantly higher than those in other trophic levels and pelagic/subbenthic fish, these species had homogeneous anthropogenic pollution sources for Cu, Zn, Cd, Hg and As. Our results show that the trace metal contents in fish were mainly affected by trophic level and habitat preference. The contribution of metal exposure from the sediment to metal accumulation in fish was lower than that in water, especially for the Cd and Hg in the sediment. These results provide valuable information for further understanding the species-specific patterns of metal accumulation in fish and the development of targeted conservation measures for the environment and fish consumers.

Contamination and oxidative stress biomarkers in estuarine fish following a mine tailing disaster

BACKGROUND

The Rio Doce estuary, in Brazil, was impacted by the deposition of iron mine tailings, caused by the collapse of a dam in 2015. Based on published baseline datasets, the estuary has been experiencing chronic trace metal contamination effects since 2017, with potential bioaccumulation in fishes and human health risks. As metal and metalloid concentrations in aquatic ecosystems pose severe threats to the aquatic biota, we hypothesized that the trace metals in estuarine sediments nearly two years after the disaster would lead to bioaccumulation in demersal fishes and result in the biosynthesis of metal-responsive proteins.

METHODS

We measured As, Cd, Cr, Cu, Fe, Mn, Pb, Se and Zn concentrations in sediment samples in August 2017 and compared to published baseline levels. Also, trace metals (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, Se and Zn) and protein (metallothionein and reduced glutathione) concentrations were quantified in the liver and muscle tissues of five fish species (Cathorops spixii, Genidens genidens, Eugerres brasilianus, Diapterus rhombeus and Mugil sp.) from the estuary, commonly used as food sources by local populations.

RESULTS

Our results revealed high trace metal concentrations in estuarine sediments, when compared to published baseline values for the same estuary. The demersal fish species C. spixii and G. genidens had the highest concentrations of As, Cr, Mn, Hg, and Se in both, hepatic and muscle, tissues. Trace metal bioaccumulation in fish was correlated with the biosynthesis of metallothionein and reduced glutathione in both, liver and muscle, tissues, suggesting active physiological responses to contamination sources. The trace metal concentrations determined in fish tissues were also present in the estuarine sediments at the time of this study. Some elements had concentrations above the maximum permissible limits for human consumption in fish muscles (e.g., As, Cr, Mn, Se and Zn), suggesting potential human health risks that require further studies. Our study supports the high biogeochemical mobility of toxic elements between sediments and the bottom-dwelling biota in estuarine ecosystems.

Concentration and Trophic Transfer of Copper, Selenium, and Zinc in Marine Species of the Chilean Patagonia and the Antarctic Peninsula Area

Patagonia and Antarctica are biodiverse regions in the Southern Hemisphere, but little is known about the levels of trace elements in marine organisms from these remote coastal ecosystems. In this study, selenium (Se), copper (Cu), zinc (Zn), and stable isotopes of nitrogen (δ¹⁵N; relative trophic level) were measured in 36 marine species collected from two locations of the Chilean Patagonia and two locations of the Antarctic Peninsula area to determine whether biomagnification of these trace elements occurs in the food webs. Results indicated that Cu, Se, and Zn levels were slightly lower than those in similar species from elsewhere, and the highest metal levels were found in marine macroinvertebrates compared with fishes. There was evidence of Cu, Se, and Zn biomagnification but only within the lower-trophic-level organisms. When assessing whole food webs, levels of these elements typically decreased from macroinvertebrates to fishes or birds, suggesting lower risks of metal toxicity to higher-level consumers.

Main drivers of mercury levels in Southern Ocean lantern fish Myctophidae

Myctophids are the most abundant fish group in the Southern Ocean pelagic ecosystem and are an important link in the Antarctic marine food web. Due to their major ecological role, evaluating the level of mercury (Hg) contamination in myctophids is important as a step towards understanding the trophic pathway of this contaminant. The concentrations of total Hg were determined in muscle, gill, heart and liver tissue of 9 myctophid species to quantify tissue partitioning variability between species. Organic Hg concentration and proportion in muscle was also determined. Hg concentrations were higher in the liver and heart than in muscle and gills, but the proportion of organic Hg was almost 100% in muscle, indicating that the main uptake route for Hg is through the diet. Most of the species analysed have similar vertical and horizontal distributions, and similar feeding modes and prey. Geographical and temporal variability of Hg concentrations was examined using samples from 3 different sampling cruise (2007/08, 2015/16 and 2016/17) and 2 locations (South Georgia and South Orkneys Islands). Our results appear to indicate a decreasing trend in Hg contamination over the last decade, particularly gill tissue, which is in agreement with a previous study on squid from the same region. There was no significant variability in Hg concentration between the different sampling locations. Hg levels were consistent with values reported previously for myctophids around the world, indicating low global-scale geographic variability. A positive relationship between fish size and Hg concentration was found for most species, with the exception of Electrona antarctica females, which may be explained through Hg elimination by egg laying. We estimate that myctophids collectively comprise a Southern Ocean mercury 'reserve' of ≈1.82 metric tonnes.

Influence of sexual dimorphism on stable isotopes and trace element concentrations in the greater hooked squid Moroteuthopsis ingens from New Zealand waters

The Chatham Rise, one of the highest offshore-primary production regions in New Zealand waters, hosts a great abundance and diversity of deep-sea cephalopods including the greater hooked squid, Moroteuthopsis ingens. Stable isotope ratios of carbon (δ¹³C) and nitrogen (δ¹⁵N) and trace element concentrations (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Ni, Pb, Se, V, and Zn) were assessed in female and male specimens of different size classes (89-563 mm mantle length). Values of δ¹³C and δ¹⁵N were overall higher in females and δ¹³C was further influenced by size and sex. Both muscular mantle (the largest fraction of the total body mass) and digestive gland (the known main storage organ for Ag, Cd, Cu and Zn in many cephalopods) tissues were analysed. Higher levels of Cd were observed in males than in females. A positive effect was found between size and Hg concentrations, which could be related to the ontogenetic descent of larger specimens into deeper waters, where they are exposed to higher Hg concentrations, and/or dietary shifts toward Hg-enriched prey with increasing size. This study provides trace element data for this abundant and ecologically important species, and further reveals higher trace element concentrations (especially Hg) in M. ingens from the Chatham Rise, compared to specimens from the sub-Antarctic zone.

Concentrations of trace elements in the organs of commercially exploited crustaceans and cephalopods caught in the waters of Thoothukudi, South India

Concentrations of trace elements (arsenic, cadmium, mercury, and lead) in tissues (muscle, gills, and digestive gland) of three commercially exploited crustaceans (Portunus sanguinolentus, Charybdis natator, and Penaeus semisulcatus) and three cephalopods (Doryteuthis sibogae, Sepia pharaonis, and Cistopus indicus) were examined. The animals were captured in the waters of Thoothukudi, and the tissues of six individuals of each species were analyzed using ICP-MS. The highest concentrations of arsenic (16.5 μg/g) and mercury (0.052 μg/g) were recorded in the digestive gland of C. natator, and cadmium (69.9 μg/g) and lead (0.351 μg/g) in the digestive gland of S. pharaonis. The edible portion of the crustaceans and cephalopods contained lower concentrations of trace elements, and these were below allowable limits set by the European Union. The edible parts of the investigated samples are safe for human consumption, but accidental contamination of the edible tissues with material from the digestive glands could lead to concerns relating to metal toxicity.

Trace elements levels in muscle and liver of a rarely investigated large pelagic fish: The Mediterranean spearfish Tetrapturus belone (Rafinesque, 1810)

We determined levels of mercury, cadmium, lead and selenium in muscle and liver of 29 specimens of a large pelagic fish rarely investigated, the Mediterranean spearfish Tetrapturus belone (Raf., 1810). The following element concentration ranking (mean ± S.D.; espressed in mg/kg dry weight) was recorded in muscle: Hg (3.401 ± 1.908) > Se (1.727 ± 0.232) > Pb (0.532 ± 0.322) > Cd (0.019 ± 0.015), and Se (6.577 ± 1.789) > Cd (5.815 ± 3.038) > Hg (2.698 ± 2.214) > Pb (0.661 ± 1.334) in liver. Levels of Hg, Se and Cd were compared to those reported for other Istiophoridae from oceanic areas and for other large predators of Mediterranean Sea, like swordfish and tuna. Organotropism of trace elements and their relation to size was discussed. Ecophysiological considerations regarding the Se-Hg relationship as well as Se-Cd indicate a possible detoxification mechanism. The implications for human consumption are briefly discussed.

Trace element analysis reveals bioaccumulation in the squid Gonatus fabricii from polar regions of the Atlantic Ocean

The boreoatlantic gonate squid (Gonatus fabricii) represents important prey for top predators-such as marine mammals, seabirds and fish-and is also an efficient predator of crustaceans and fish. Gonatus fabricii is the most abundant cephalopod in the northern Atlantic and Arctic Ocean but the trace element accumulation of this ecologically important species is unknown. In this study, trace element concentrations (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn) were analysed from the mantle muscle and the digestive gland tissue of juveniles, adult females, and adult males that were captured south of Disko Island off West-Greenland. To assess the feeding habitat and trophic position of this species, stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N) were measured in their muscle tissue. Mercury concentrations were positively correlated with size (mantle length) and trophic position. The Hg/Se ratio was assessed because Se has been suggested to play a protective role against Hg toxicity and showed a molar surplus of Se relative to Hg. Cadmium concentrations in the digestive gland were negatively correlated with size and trophic position (δ¹⁵N), which suggested a dietary shift from Cd-rich crustaceans towards Cd-poor fish during ontogeny. This study provides trace element concentration data for G. fabricii from Greenlandic waters, which represents baseline data for a northern cephalopod species. Within West-Greenland waters, G. fabricii appears to be an important vector for the transfer of Cd in the Arctic pelagic food web.

Mercury levels in Southern Ocean squid: Variability over the last decade

The concentrations of total and proportions of organic mercury were measured in tissues of 355 individuals of 8 species of Southern Ocean squid (Alluroteuthis antarcticus, Bathyteuthis abyssicola, Filippovia knipovitchi, Galiteuthis glacialis, Gonatus antarcticus, Kondakovia longimana, Psychroteuthis glacialis and Slosarczykovia circumantarctica). Squid were caught around South Georgia (Scotia Sea) during 5 cruises, between the austral summers of 2006/07 to 2016/17 to evaluate temporal changes in bioaccumulation and tissue partitioning. Total mercury concentrations varied between 4 ng g^-1 and 804 ng g^-1 among all tissues. Net accumulation of mercury in muscle with size was observed in A. antarcticus, B. abyssicola and P. glacialis, but no relationship was found for S. circumantarctica and lower concentrations were observed in larger individuals of G. glacialis. Muscle tissues had the highest mercury concentrations in the majority of species, except for F. knipovitchi for which the digestive gland contained highest concentrations. In terms of the percentage of organic mercury in the tissues, muscle always contained the highest values (67%-97%), followed by the digestive gland (22%-38%). Lowest organic mercury percentages were found consistently in the gills (9%-19%), suggesting only low levels of incorporation through the dissolved pathway and/or a limited redistribution of dietary organic mercury towards this tissue. Overall, results are indicative of a decreasing trend of mercury concentrations in the majority of analysed species over the last decade. As cephalopods are an important Southern Ocean trophic link between primary consumers and top predators, these changes suggest decreasing mercury levels in lower trophic levels and an alleviation of the mercury burden on higher predators that consume squid.

Response of vanadium bioaccumulation in tissues of Mugil cephalus (Linnaeus 1758)

Vanadium accumulation levels in different tissues (muscle and organs) of the striped mullet Mugil cephalus (Linnaeus, 1758) and possible relationships with blood parameters were evaluated in a Natural Protected Area (Lake Faro, Sicily, Italy), during the winter of 2017. Hematological parameters (red blood cell, RBC; white blood cell, WBC; hemoglobin concentration, Hb; hematocrit, Hct; mean corpuscular volume, MCV; mean corpuscular hemoglobin, MCH; mean corpuscular hemoglobin concentration, MCHC; thrombocytes, TC), biometric indices (weight, total and fork length), and vanadium levels in muscles and organs (gills, liver, stomach and intestine) were determined. Statistical analyses showed significant differences in concentrations of vanadium of the analyzed tissue of M. cephalus and a positive relationship between vanadium concentration in the liver and some hematological parameters (RBC, Hb and Hct) and biometric indices. Our results underline the importance of fish blood parameters as sensitive indicators of toxic impact of environmental factors such as metals. This study, focusing on an ongoing topic, represents a valuable contribution to research concerning the monitoring and prevention of vanadium pollution in aquatic organisms and environments.

Heavy metal content in farmed rainbow trout in relation to aquaculture area and feed pellets

Fish contamination by heavy metals, even at low levels, has an adverse effect on human health. Mercury (Hg), cadmium (Cd), and lead (Pb) are the most common heavy metals that contaminate sea foods. Rainbow trout is a fish species which is widely cultured in fresh water regions, e.g. in Yasuj, southwest of Iran. Heavy metal contamination was measured in three different culture areas (A, B, and C), with three different feed pellets used in Yasuj farms (I, II, and III). The sampling was conducted during February-April 2018 and the metals were measured using cold vapour atomic absorption with a Perkin Elmer 4100. The mean values of Hg, Cd, and Pb levels in the muscular tissue of the samples were 0.022, 0.105, and 1.07 mg/kg, respectively. Concentrations of Hg and Cd in edible tissues of rainbow trout were lower than the permitted values set by the WHO, the FDA, and the EC. The samples fed on mixture pellets III showed a significantly higher Hg content and a lower concentration of Cd in the muscle tissue compared to those given feed mixtures I and II (P < 0.05). Pearson correlation tests revealed significant correlations between the Cd and Pb concentrations and the weight of the fish samples (r = –0.519, r = –0.580). The lowest Cd concentration (0.076 mg/kg–1) was found in site A located close to the spring and not polluted by sewage from urban or rural areas. The study showed a correlation between the concentration of heavy metals in the fish samples and their weight, the degree of pollution, and the feeding mixture used in the farms.

Concentrations of Thirteen Trace Metals in Scales of Three Nototheniid Fishes from Antarctica (James Ross Island, Antarctic Peninsula)

In this study, we assessed concentrations of 13 trace metals in the scales of Notothenia coriiceps, Trematomus bernacchii and Gobionotothen gibberifrons caught off the coast of James Ross Island (Antarctic Peninsula). Overall, our results for scales broadly match those of previous studies using different fish and different organs, with most metals found at trace levels and manganese, aluminium, iron and zinc occurring at high levels in all species. This suggests that scales can serve as a useful, non-invasive bioindicator of long-term contamination in Antarctic fishes. High accumulation of manganese, aluminium, iron and zinc is largely due to high levels in sediments associated with nearby active volcanic sites. Manganese, vanadium and aluminium showed significant positive bioaccumulation in T. bernacchii (along with non-significant positive accumulation of iron, zinc, cobalt and chromium), most likely due to greater dietary specialisation on sediment feeding benthic prey and higher trophic species. Levels of significance in bioaccumulation regressions were strongly affected by large-scale variation in the data, driven largely by individual differences in diet and/or changes in habitat use and sex differences associated with life stage and reproductive status. Increased levels of both airborne deposition and precipitation and meltwater runoff associated with climate change may be further adding to the already high levels of manganese, aluminium, iron and zinc in Antarctic Peninsula sediments. Further long-term studies are encouraged to elucidate mechanisms of uptake (especially for aluminium and iron) and possible intra- and interspecific impacts of climate change on the delicate Antarctic food web.

Potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) in fish and prawn in the Persian Gulf, Iran

This study aimed to speciate and quantify potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs), in addition to estimate potential human health risk of PTEs (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se, V, and Zn) through the consumption of three edible fish species (Leuciscus vorax, Liza abu, and Coptodon zillii) and two prawn species (Metapenaeus affinis and Penaeus semisulcatus) collected from Arvand River and Musa Estuary in the Persian Gulf. The concentration of As in prawn species exceeded permissible limit set by international organizations. PAHs were dominated by low molecular weight species such as naphthalene, phenanthrene, and, fluorene but generally exhibited low mean concentrations in fish and prawn samples. The human health hazard posed by PTEs was assessed using methods that consider estimated daily intake (EDI), estimated weekly intake (EWI), target hazard quotients (THQ), and combined THQ. The results suggested that elevated As concentrations in almost all prawn samples may pose a probable health hazard to local inhabitants.

Arsenic, selenium, and metals in a commercial and vulnerable fish from southwestern Atlantic estuaries: distribution in water and tissues and public health risk assessment

The anadromous catfish Genidens barbus is a vulnerable and economically important species from the Southwestern Atlantic Ocean. Concentrations of As, Co, Fe, Se, and Zn were determined in water and muscle, gill, and liver of catfish from two southwestern Atlantic estuaries (Brazil and Argentina) and health risk via fish consumption was evaluated. High spatial variability was observed in the metals, As, and Se distribution for both estuaries. Considering all tissues, element concentrations (mg/kg, wet weight) were As = 0.41-23.50, Co = 0.01-2.9, Fe = 2.08-773, Se = 0.15-10.7, and Zn = 3.97-2808). Most of the trace elements tended to be higher in Brazil than in Argentina, except for Co, Fe, Se, and Zn in liver and Fe and Co in muscle and gill, respectively. Arsenic accumulation order was muscle > liver ≥ gill. Only As (muscle) was above the maximum recommended by international guidelines at both estuaries. The target hazard quotient ranged from 0.10 to 1.58, suggesting that people may experience significant health risks through catfish consumption. Supposing that the inorganic/toxic As ranged between 1 and 20% of the total, the recommended maximum intakes per capita bases were 6.1-95 and 8.4-138 kg/year (wet weight) for Brazil and Argentina, respectively. Carcinogenic risk for As intake was within the acceptable range but close to the recommended limit (> 10^-4). These results highlights the importance of quantifying the As species in catfish muscle in order to generate more reliable risk estimates.

Horizontal and vertical food web structure drives trace element trophic transfer in Terra Nova Bay, Antarctica

Despite a vast amount of literature has focused on trace element (TE) contamination in Antarctica during the last decades, the assessment of the main pathways driving TE transfer to the biota is still an overlooked issue. This limits the ability to predict how variations in sea-ice dynamics and productivity due to climate change will affect TE allocation in the food web. Here, food web structure of Tethys Bay (Terra Nova Bay, Ross Sea, Antarctica) was first characterised by analysing carbon and nitrogen stable isotopes (δ¹³C, δ¹⁵N) in organic matter sources (sediment and planktonic, benthic and sympagic primary producers) and consumers (zooplankton, benthic invertebrates, fish and birds). Diet and trophic position were also characterised using Bayesian mixing models. Then, relationships between stable isotopes, diet and TEs (Cd, Cr, Co, Cu, Hg, Ni, Pb and V) were assessed in order to evaluate if and how horizontal (organic matter pathways) and vertical (trophic position) food web features influence TE transfer to the biota. Regressions between log[TE] and δ¹³C revealed that the sympagic pathway drives accumulation of V in primary consumers and Cd and Hg in secondary consumers, and that a coupled benthic/pelagic pathway drives Pb transfer to all consumers. Regressions between log[TE] and δ¹⁵N showed that only Hg biomagnifies across trophic levels, while all the others TEs showed a biodilution pattern, consistent with patterns observed in temperate food webs. Although the Cd behavior needs further investigations, the present findings provide new insights about the role of basal sources in the transfer of TEs in polar systems. This is especially important nowadays in light of the forecasted trophic changes potentially resulting from climate change-induced modification of sea-ice dynamics.

Heavy metal contamination in two commercial fish species of a trans-Himalayan freshwater ecosystem

Toxic metals have disturbed the quality of freshwater ecosystems worldwide. The concentration of heavy metals was investigated in liver, gills and muscle tissues of Schizothorax niger and Cyprinus carpio captured from river Jhelum of Kashmir Himalaya. The heavy metals displayed a wide range of disparity in studied tissues, seasons, sites and species. Cu²⁺ exhibited the highest concentration (279.6 μg/kg) in the liver tissues of S. niger in autumn at site 2 and the lowest (53.1 μg/kg) in the gill tissues in winter at site 1. In C. carpio, the Cu²⁺ was recorded highest (309.4 μg/kg) in the liver tissues in autumn at site 2. The concentration of Zn²⁺ was found highest (575.7 μg/kg) in the liver tissues at site 2 and the lowest (65.8 μg/kg) was recorded in the muscle tissues in autumn at site 1. Zn²⁺ was recorded highest (416.6 μg/kg) in the liver tissues in autumn at site 3 and lowest (51.5 μg/kg) in the gills of C. carpio during winter at site 1 (control). The concentration of Pb²⁺ (14.42 μg/kg) and Fe²⁺ (323.9 μg/kg) was observed in the liver tissue and gills of S. niger at site 3. Similar levels of Pb²⁺ and Fe²⁺ were recorded in the tissues of C. carpio at different sites. Four-way ANOVA (four way) indicated a statistically significant variation (p ≤ 0.05) in heavy metals with the sites, seasons, species and organs. The study emphasises the utmost need to monitor the level of heavy metals in S. niger on a regular basis as this native fish species is showing a continuous decline in the freshwater ecosystems of Kashmir Valley.

Inconsistent responses of liver mitochondria metabolism and standard metabolism in Silurus meridionalis when exposed to waterborne cadmium

We investigated the standard metabolic rate and liver mitochondria metabolism of the southern catfish when exposed to waterborne cadmium. Juvenile southern catfish were exposed to waterborne cadmium concentrations (0, 62.5, 125, 250 and 500 μg/L, respectively) for 8 weeks, and the final body mass, the standard metabolic rate, the state III respiration rate, the activity of cytochrome C oxidase (CCO) of liver mitochondria, and the hepatosomatic index (HSI) were determined. The results showed that the 62.5 μg/L, 125 μg/L, and 250 μg/L experiment groups had a significantly higher standard metabolic rate than that of the control group. Standard metabolic rate in the 500 μg/L experiment group did not differ from the control group. State III respiration rate of liver mitochondria decreased with an increase in cadmium concentration. The 125 μg/L, 250 μg/L, and 500 μg/L experiment groups had a significantly lower state III respiration rate than that of the control group. The activity of CCO in the 500 μg/L experiment group was significantly lower than that of the control group. These results suggest that at low cadmium concentrations, the southern catfish could continuously improve the standard metabolism to provide extra energy in response to the cadmium stress. Cadmium exposures caused damage to the structure and function of liver mitochondria and decreased the activity of mitochondria enzymes, which results in a decrease in the energy of the liver metabolism. The adjustment of the metabolism of liver mitochondria in southern catfish was inconsistent with the adjustment of individual standard metabolism.

High cadmium and mercury concentrations in the tissues of the orange-back flying squid, Sthenoteuthis pteropus, from the tropical Eastern Atlantic

The orange-back flying squid, Sthenoteuthis pteropus, plays an important role in the eastern tropical Atlantic Ocean (ETA) pelagic food web, as both predator and prey. Specimens of S. pteropus were caught off the Cape Verde Islands and concentrations of Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V, and Zn were measured in the digestive gland. Among the analysed elements, Cd showed the highest average concentration with values among the highest ever recorded in cephalopods. In addition to the digestive gland, Hg concentrations were also analysed in the buccal mass and mantle tissue. Among the three tissues, buccal mass showed the highest Hg concentrations. In females, Hg concentrations in the buccal mass were positively correlated with stable isotope ratios (δ¹³C and δ¹⁵N) and mantle length, showing both bioaccumulation with age and bioamplification along the trophic levels. High Cd and Hg concentrations in the digestive gland and muscle respectively would lead to elevated exposure of squid-eating top predators such as yellowfin tuna, swordfish or dolphinfish, which are commercially harvested for human consumption. This study provides a deeper understanding of the trace element contamination in an abundant and ecologically important, but poorly studied pelagic squid in the ETA.

First data on uranium uptake in three nototheniid fishes from Antarctica (James Ross Island)

Recent studies have confirmed historic atmospheric deposition of uranium in Antarctica, with a steep and significant increase in levels deposited since the 1980s in Antarctic Peninsula ice core samples. To date, however, there has been little or no attention paid to uranium in the Antarctic food web. Here, we present results for uranium content in scales of three common nototheniid species (Trematomus bernacchii, Gobionotothen gibberifrons, Notothenia coriiceps) from coastal waters off James Ross Island (Antarctic Peninsula). While mean total uranium levels (mean ± SD) were low and similar between species (N. coriiceps 0.08 μg g^-1 ± 0.01, T. bernacchii 0.17 μg g^-1 ± 0.10; G. gibberifrons 0.11 μg g^-1 ± 0.04), linear regressions against standard length indicated bioaccumulation in T. bernacchii (ANOVA, F = 7.8349, P = 0.0076). We suggest this may be the result of dietary specialisation on prey with calcareous shells that accumulate uranium. To the best of our knowledge, this paper provides the first quantitative baseline data on uranium levels in coastal Antarctic nototheniids. While the low levels recorded are unlikely to represent a threat within the food chain, we suggest that further long-term trophic studies (including stable isotope analysis) are needed, recognising that the feeding ecology of individual species (and even individuals) can have a strong effect on overall trends.

Heavy metals concentration and human health risk assessment in seven commercial fish species from Asafo Market, Ghana

Health risk assessment and heavy metal accumulation were evaluated in the muscles of widely consumed Trachurus trachurus, Lutjanus fulgens, Lutjanus goreensis, Acanthocybium solandri, Pagellus bellottii, Scomber colias and Dentex congoensis fish species in Asafo, Ghana. The fish samples were prepared using a wet digestion method and the heavy metals analysis was performed with the flame atomic absorption spectrophotometer (UNICAM 969). The results revealed that Mn, Cu, Zn, Cd, and Pb concentrations were below the permissible values set by several health institutions. The health risk assessment based on non-carcinogenic and cancer factors effect indicates no adverse health effect of fish intake. The results of heavy metal concentrations showed that different varieties of fish could be safe for human intake and the results are anticipated to create alertness among the local people.

Tissue-Specific Antioxidative Responses and Cadmium Accumulation in Silurus meridionalis Under Chronic Waterborne Cadmium Exposure

In this study, the oxidative damage, antioxidative responses and cadmium (Cd) accumulation in juvenile Silurus meridionalis were studied, after S. meridionalis were exposed to 0 (control), 62.5, 125, 250 and 500 µg Cd/L for 56 days. Cd accumulation, malondialdehyde, superoxide dismutase (SOD), catalase, glutathione (GSH) and total antioxidant capacity (T-AOC) were determined in gill, liver, kidney and intestine tissues. The results showed that the Cd accumulation in S. meridionalis was dose-dependent and tissue-specific, with the highest Cd content in the kidney, followed by the liver, gill, and intestine. Waterborne Cd stress in S. meridionalis was expressed as tissue-specific oxidative damage and antioxidant responses in gill, liver, kidney and intestine tissues. Waterborne Cd exposure induced the most significant oxidative damage in the gill, followed by the liver and kidney, while the intestine showed no sensitivity to waterborne Cd exposure. The antioxidants, such as SOD in the liver, kidney and intestine, as well as T-AOC and GSH in the gill, liver and kidney, were sensitive to waterborne Cd exposure.

Heavy metals (As, Hg and V) and stable isotope ratios (δ13C and δ15N) in fish from Yellow River Estuary, China

The Yellow River Estuary is a significant fishery, but at present there are few studies about the concentrations of arsenic (As), mercury (Hg) and vanadium (V) in fish from this area, which might cause potential health risk to fish consumers. The aim of this study was to research on the accumulation and potential sources of heavy metals in the fish of the Yellow River Estuary. Arsenic, Hg, V and stable isotope ratios (δ¹⁵N and δ¹³C) in 11 species of 129 fish were analyzed. Results showed that the concentrations of As and Hg were all lower than the guideline levels established by international organizations and legal limits by several countries. The mean concentrations of V in samples in this study were significantly higher than the results of previous studies on other regions. Arsenic, Hg and V significantly differed across species (P<0.05), which might be due to the different foraging habitats and dietary habits of the studied fish. Values of δ¹⁵N and δ¹³C in fish from the study area ranged from 5.1‰ to 14.6‰ and from -27.6‰ to -14.5‰, indicating a wide range of trophic positions and energy sources. There was evidence of bioaccumulation of Hg, which could be explained by the positive correlation between Hg concentrations and δ¹⁵N in fish. Through estimation of daily intake of inorganic As (iAs), Hg and V via fish consumption, the heavy metal contamination level of fish samples fell in an acceptable range, indicating no potentially hazardous for human health.

A Global Overview of Exposure Levels and Biological Effects of Trace Elements in Penguins

Trace elements are chemical contaminants that can be present almost anywhere on the planet. The study of trace elements in biotic matrices is a topic of great relevance for the implications that it can have on wildlife and human health. Penguins are very useful, since they live exclusively in the Southern Hemisphere and represent about 90% of the biomass of birds of the Southern Ocean. The levels of trace elements (dry weight) in different biotic matrices of penguins were reviewed here. Maps of trace element records in penguins were included. Data on exposure and effects of trace elements in penguins were collected from the literature. The most reported trace elements in penguins are aluminum, arsenic, cadmium, lead, mercury, copper, zinc, and manganese. Trace elements have been measured in 11 of the 18 species of penguins. The most studied biotic matrices are feathers and excreta. Most of the studies have been performed in Antarctica and subantarctic Islands. Little is known about the interaction among metals, which could provide better knowledge about certain mechanisms of detoxification in penguins. Future studies of trace elements in penguins must incorporate other metals such as vanadium, cobalt, nickel, and chromium. Data of metals in the species such as Eudyptes pachyrhynchus, Eudyptes moseleyi, Eudyptes sclateri, Eudyptes robustus, Eudyptes schlegeli, Spheniscus demersus, Spheniscus mendiculus, and Megadyptes antipodes are urged. It is important to correlate levels of metals in different biotic matrices with the effects on different species and in different geographic locations.

From Antarctica to the subtropics: Contrasted geographical concentrations of selenium, mercury, and persistent organic pollutants in skua chicks (Catharacta spp.)

Seabirds integrate bioaccumulative contaminants via food intake and have revealed geographical trends of contamination in a variety of ecosystems. Pre-fledging seabird chicks are particularly interesting as bioindicators of chemical contamination, because concentrations in their tissues reflect primarily dietary sources from the local environment. Here we measured 14 trace elements and 18 persistent organic pollutants (POPs) in blood of chicks of skuas that breed in four sites encompassing a large latitudinal range within the southern Indian Ocean, from Antarctica (Adélie Land, south polar skua Catharacta maccormicki), through subantarctic areas (Crozet and Kerguelen Islands, brown skua C. lonnbergi), to the subtropics (Amsterdam Island, C. lonnbergi). Stables isotopes of carbon (δ¹³C, feeding habitat) and nitrogen (δ¹⁵N, trophic position) were also measured to control for the influence of feeding habits on contaminant burdens. Concentrations of mercury (Hg) and selenium (Se) were very high at all the four sites, with Amsterdam birds having the highest concentrations ever reported in chicks worldwide (4.0 ± 0.8 and 646 ± 123 μg g^-1 dry weight, respectively). Blood Hg concentrations showed a clear latitudinal pattern, increasing from chicks in Antarctica to chicks in the subantarctic and subtropical islands. Interestingly, blood Se concentrations showed similar between-population differences to Hg, suggesting its involvement in protective mechanisms against Hg toxicity. Chicks' POPs pattern was largely dominated by organochlorine pesticides, in particular DDT metabolites and hexachlorobenzene (HCB). Skua chicks from subantarctic islands presented high concentrations and diversity of POPs. By contrast, chicks from the Antarctic site overall had the lowest concentrations and diversity of both metallic and organic contaminants, with the exception of HCB and arsenic. Skua populations from these sites, being naturally exposed to different quantities of contaminants, are potentially good models for testing toxic effects in developing chicks in the wild.