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See detailOccurrence of legacy and emerging organic pollutants in whitemouth croakers from Southeastern Brazil
Pizzochero da Costa, Ana Carolina ULiege; de la Torre, Adrian; Sanz, Paloma et al

in Science of the Total Environment (in press)

The whitemouth croaker (Micropogonias furnieri) is one of the most commercially important species along the Atlantic coast of South America. Moreover, some of its biological traits (long life span ... [more ▼]

The whitemouth croaker (Micropogonias furnieri) is one of the most commercially important species along the Atlantic coast of South America. Moreover, some of its biological traits (long life span, inshore feeding, high trophic position) make this species a suitable sentinel of coastal pollution. Here, we investigated contamination by multiple legacy and emerging organic pollutants, such as brominated and chlorinated flame retardants, polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), in whitemouth croakers from two estuaries (Guanabara and Sepetiba Bays) located in industrialized and urbanized areas in Rio de Janeiro State, Southeastern Brazil. Furthermore, we assessed how biological and ecological features could explain the observed contamination patterns. Regarding brominated flame retardants, concentrations of polybrominated diphenyl ethers (PBDEs) varied from 7.6 to 879.7 pg g-1 wet weight (w.w.), with high contribution of tetra-, penta-, hexa- and deca-BDEs. The sum of chlorinated flame retardants (dechlorane-related compounds, ΣDRC) ranged from <LOD to 41.1 pg g-1 w.w., mostly represented by Dechlorane 603 and Dechlorane Plus (DP). Concentrations of PCDDs and PCDFs varied from <LOD to 1.7 pg g-1 w.w., while the Toxic Equivalent (TEQ-PCDD/Fs) levels ranged from 0.1 to 0.2 pg g-1 w.w. Positive correlations between δ15N and concentrations of tri-, tetra- and penta-BDEs, as well as ΣDRC, DP and anti-DP isomers suggested that ecological factors (namely biomagnification along the food web) influence contamination of whitemouth croakers in the estuaries studied. Moreover, the sum of PBDEs (ΣPBDE), tri- and tetra-BDEs concentrations were negatively correlated with fish size, suggesting that depuration by fishes and/or habitat shift throughout the whitemouth croaker’s life cycle might also influence concentrations. Overall, our study emphasized the need for further investigations to help understand the complex patterns of bioaccumulation and biomagnification that seem to exist in Southeastern Brazil. [less ▲]

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See detailHg in Arctic top predators: insights from a captive experiment on hooded seals Cystophora cristata.
Pinzone, Marianna ULiege; Tessier, Emmanuel; Bérail, Sylvain et al

Scientific conference (2019, May 06)

Arctic predators like true seals have been experiencing a strong increase in Hg levels in their tissues in the last 150 years. This is in contrast with other terrestrial animals or other parts of the ... [more ▼]

Arctic predators like true seals have been experiencing a strong increase in Hg levels in their tissues in the last 150 years. This is in contrast with other terrestrial animals or other parts of the world. Dietary Hg accumulates and biomagnifies in marine food webs in its most toxic form, monomethylmercury (MMHg). Hg seven stables isotopes (196Hg, 198Hg, 199Hg, 200Hg, 201Hg, 202Hg and 204Hg) undergo both mass-dependent and mass-independent fractionation (MDF and MIF, respectively) as a result of abiotic and biotic reactions occurring in the environment and within the organism. For this reason, they are a promising tool for tracing Hg cycling in the natural environment. The interpretation of Hg isotopic data remain however a challenge, especially when taking into account species such as Arctic true seals, which have highly complex life styles and metabolism. In 2012, six pups of hooded seals Cystophora cristata were captured on the ice edge of the Greenland Sea and kept in captivity for 2 years. During this period, they were fed on a constant diet made of Norwegian herring Clupea harengus and vitamin complements. This allowed us to study Hg kinetic in an Arctic top predator without the influence of age, distribution and diet specialization. The main objective was to select the tissue in which the information about Hg pathways would be conserved, leading to the optimal tracing of Hg sources along the food web. Total Hg (THg) concentrations were determined on a Milestone direct mercury analyzer, while MeHg and IHg concentrations were determined by isotope dilution-gas chromatography-inductively coupled plasma-mass spectrometer (ID-GC-ICP-MS) following microwave-assisted extraction and aqueous phase derivatization. Mercury isotopic composition analysis was performed using cold vapor generation (CVG) with multicollector-inductively coupled plasma-mass spectrometer (MC-ICP-MS, Nu Instruments). The analysis was conducted in seal muscle, liver, hair, and kidney, plus muscle of herring. Hg speciation changed significantly among tissues. Hair and muscle were predominantly enriched in MMHg (range: 84 to 98% and 74 to 95%, respectively) relative to liver and kidney (range: 7 to 38% and 4 to 27% respectively) that tend to mainly accumulate iHg. δ202Hg values were positively related with levels of MMHg (p > 0.0001, R2 = 0.531). With higher values found in hair, followed by muscle, liver and kidney. Δ199Hg and Δ201 values were not influenced by Hg species composition in tissues, as well as slope values of Δ199Hg/Δ201Hg. The low fraction of MMHg (< 30%) found in liver and kidney determines a large variability of isotopic and contamination values. When calculating the isotopic trophic enrichment between herring and hooded seals’ tissues, a significant 202Hg enrichment resulted between seal hair and kidney and herring (p = 0.011 and p < 0.001), indicating important MDF between the ingested prey and these tissues. Instead, a significant MIF (Δ199Hg and Δ201 values) was observed only between seals’ kidney and herring (p = 0.0003). Our results show that: (1) Hg isotopic composition reflects Hg molecular speciation; (2) as a result of isotopic incorporation during tissue turnover, hair and kidney present a strong trophic MDF; and (3) with the exception of kidney, MIF signal is conserved in all tissues during assimilation of prey items. Based on these observations, we believe that muscle is the optimal monitoring tissue for tracing of Hg sources since both the MDF and MIF signals are conserved from prey to predator. The important MDF observed in hair instead, make this tissue the best option for the analysis of Hg biomagnification along food webs. [less ▲]

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See detailMercury in marine vertebrates: new insights from speciation and isotopic composition
Das, Krishna ULiege

Conference (2019, March 07)

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See detailIt's a long way to the Arctic: First record of plastic debris in the stomach of a hooded seal pup in the Greenland Sea
Pinzone, Marianna ULiege; Nordoy, Erling; Das, Krishna ULiege

Poster (2019, January 23)

In April 2017, we conducted a cruise in the Greenland Sea, on board of the RV “Helmer Hansen”. The main objective was to collect tissue samples of hooded seal (Cystophora cristata) pups, during the post ... [more ▼]

In April 2017, we conducted a cruise in the Greenland Sea, on board of the RV “Helmer Hansen”. The main objective was to collect tissue samples of hooded seal (Cystophora cristata) pups, during the post-weaning fast. Four hooded seals (1 male, 3 females) were sampled. Hooded seals’ length ranged between 93 and 105 cm. We estimated the pups to be ± 20 days old. We examined the digestive apparatus of all pups for the presence of prey and/or milk. Most stomachs and intestines were empty, except for hooded seal pup #H1-17 that contained milk at the end of the small intestine, and #H5-17, which contained three semi-digested shrimps (possibly Themisto spp.) and five pieces of plastic debris in its stomach. The latter consisted of buoyant, light-plastic pieces, originating from a larger food package from a well-known food manufacturing company. Their length ranged from 0.03cm to 11.2cm, their width ranged from 0.08cm to 7.0cm. Hooded seals from the Greenland Sea stock give birth in the pack ice in late March. Two-three weeks after weaning, pups start searching for food at the outer edge of the pack ice. During the first excursions, blueback pups focus on ice-associated crustaceans such as Themisto spp. The presence of plastic debris in one of the pups, however, was rather surprising. Many observations exist of Arctic animals (seabirds, sharks, whales) ingesting plastic debris. Plastic reaches the Northeastern Atlantic and the Arctic Ocean from highly populated southern latitudes via the Gulf Stream. In our case, the plastic debris seem to derive from a distribution site in Texas. Mysticetes may accidentally ingest floating material along with prey species when filter feeding. Seabirds may actively feed on plastic due to the resemblance with their normal prey. On the contrary, seals that feed selectively on fish, crustaceans and deep-water cephalopods have not been recorded to feed on plastic debris until now. To our knowledge, this is the first record of plastic ingestion by a phocidae species in the Arctic. The decrease in ice cover and thickness, as well as a dramatic increase in the use and expel of human made plastic during the last decades may have increased plastic scattering at the water surface of the Arctic Ocean. Increased availability of plastic, even in the remote areas of the pack ice, may currently increase the risk of plastic being eaten by unexperienced, hungry seal pups. [less ▲]

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See detailMercury levels in top predators as a valuable marker of environmental state and potential health risk to Arctic marine biota
Pinzone, Marianna ULiege; Nordoy, Erling; Desforges, Jean-Pierre et al

Poster (2019, January 23)

Mercury (Hg) in Arctic biota is increasing in contrast with trends in the rest of the world. In top predators, tissue levels surpassed the established toxicity thresholds. New research has revealed how ... [more ▼]

Mercury (Hg) in Arctic biota is increasing in contrast with trends in the rest of the world. In top predators, tissue levels surpassed the established toxicity thresholds. New research has revealed how the Arctic Hg cycle has altered because of sea-surface temperature increase and sea-ice cover decline. True seals are Arctic top predators. As such, Hg level in their tissue may represent a valuable integrator for changes in Hg cycling in their food chain. Our objective was to assess how the health risk associated with Hg exposure has evolved in the last 20 years in response to environmental changes. We measured Total-Hg levels in liver of hooded seals Cystophora cristata (N = 10), harp seals Pagophilus groenlandicus (N = 13) and ringed seals Pusa hispida (N = 24) through Atomic Absorption Spectrometry (DMA-80 Milestone). We grouped seals in five toxicity risk classes and compared them to the results of Dietz et al. (2005), based upon effect threshold categories calculated for harp seals by Ronald et al. (1977). Overall, hooded seals presented the highest values, followed by ringed seals and harp seals (all p < 0.05). 100% of harp seals (all ages) were in the “no effect” category, as well as yearlings of hooded and harp seals. 22% of sub-adults and 45% of adult ringed seals belonged to the “low risk” category. Conversely, all hooded seals resulted at risk with 100% of sub-adults and 25% of adults in the “low risk” class, 25% of adults in the “high risk” class and 50% of adults in the “severe risk” class. Our classification resulted very different from the 2000s when only 20% of the hooded seals’ population was at “high risk” and 20% of ringed seals was at “low risk”. This shows that Arctic true seals are at increasing toxicity risk as a consequence of the undergoing environmental changes, with some species (hooded seal) being more affected than others (harp seal). The change in length of ice season may have determined a shift in prey diversity, modifying levels of Hg exposure to seals, while the decrease in ice cover altered rates of Hg methylation in the water column and consequently its bioavailability. Our future goal is to correlate ice-cover data with seals’ Hg levels in the last 100 years, to confirm the link between climate change and Hg accumulation in seals and potentially foresee future trends of toxicity risk in Arctic top predators. [less ▲]

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See detailChanges in stable isotope compositions during fasting in phocid seals
Habran, Sarah ULiege; Damseaux, France ULiege; Pomeroy, Paddy et al

in Rapid Communications in Mass Spectrometry (2019)

RATIONALE: The grey seal, Halichoerus grypus (GS), and the northern elephant seal, Mirounga angustirostris (NES), come ashore for reproduction. This period involves intense physiological processes such as ... [more ▼]

RATIONALE: The grey seal, Halichoerus grypus (GS), and the northern elephant seal, Mirounga angustirostris (NES), come ashore for reproduction. This period involves intense physiological processes such as lactation in females and a developmental post-weaning fast in juveniles. Previous studies have shown δ13C and δ15N values are affected by starvation, but the precise effects of fasting associated to lactation and post-weaning fast in seals remains poorly understood. METHODS: To examine the effect of lactation and post-weaning fast on stable isotopes in GS and NES, blood and hair were sampled from twenty-one GS mother-pup pairs on the Isle of May and on twenty-two weaned NES pups at Año Nuevo State Reserve during their respective breeding seasons. Milk samples were also collected from GS mothers. Stable isotope measurements were performed with an isotope ratio mass spectrometer coupled to an N-C elemental analyser. RESULTS: Changes in stable isotope ratios in blood components during fasting were similar and weak between GS and NES mothers especially in blood cells (GS: Δ15N = 0.05‰, Δ13C = 0.02‰; NES: Δ15N = 0.1‰, Δ13C = 0.1‰). GS showed a 15N discrimination factor between maternal and pup blood cells and milk, but not for 13C. The strongest relationship between the isotopic compositions of the mother and the pup was observed in the blood cells. CONCLUSIONS: Isotopic consequences of lactation, fasting, and growth seem limited in NES and GS, especially in medium-term integrator tissues of feeding activity such as blood cells. Stable isotope ratios in the blood of pups and mothers are correlated. We observed a subtle mother-to-pup fractionation factor. Our results suggest that pup blood cells are mostly relevant for exploring the ecology of female seals. [less ▲]

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See detailMercury speciation and stable isotopic composition in marine vertebrates: new insights and perspectives
Das, Krishna ULiege; Pinzone, Marianna ULiege; Cransveld, Alice et al

Conference (2018, December 14)

Mercury (Hg) is a persistent toxic compound whose amount in the global biosphere has at least tripled since industrialization. Recently, the study of the seven Hg stable isotopes has emerged as a new ... [more ▼]

Mercury (Hg) is a persistent toxic compound whose amount in the global biosphere has at least tripled since industrialization. Recently, the study of the seven Hg stable isotopes has emerged as a new promising technique affording to explore the Hg cycle both in situ and in laboratory. Mercury stable isotopes display both mass dependent fractionation (MDF, reported as δ202Hg) and mass independent fractionation (MIF, reported as Δ199Hg and Δ201Hg). The combination of both values should allow to trace back sources and pathways of Hg and methylmercury (MeHg). But, so far, few studies have considered Hg isotopes in marine vertebrates. Thus, our general objective is to study Hg accumulation in marine predator species including, the European seabass, Dicentrarchus labrax, and the hooded seal, Cystophora cristata. By combining both in situ and experimental investigations, we aim to characterize the Hg profile (THg, MeHg and isotopy) of wild populations, to assess whether Hg isotopes differ between populations and could give indications on Hg sources, with special attention paid to differentiate local versus global Hg sources. [less ▲]

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See detailA meta-analysis of isotopic compositions of North Sea marine mammals
Damseaux, France ULiege; Lepoint, Gilles ULiege; Pomeroy, Paddy et al

Conference (2018, September 18)

For over a decade, the North Sea has been undergoing significant changes due to global changes, global warming and fishing. We conducted meta-analyses on marine mammals sampled in the North Sea to test ... [more ▼]

For over a decade, the North Sea has been undergoing significant changes due to global changes, global warming and fishing. We conducted meta-analyses on marine mammals sampled in the North Sea to test the potential antropogenic impact on feeding behaviour of grey seals, harbour seals and harbour porpoises. Data included δ13C and δ15N values measured in blood cells and muscles from the three species. SIBER, an isotopic niche quantification approach, is used to highlight potential dietary similarity and thus competition between marine mammal species. Harbour seals sampled in Germany showed the highest δ15N values, reflecting a trophic position at the top of the food web, alongside grey seals. In contrast, harbour porpoises sampled from Germany displayed the lowest trophic position. The ellipse overlapping between German harbour and grey seals was very important, showing similarity in, and therefore potential competition for, food sources. On the other hand, the harbour seal and the harbour porpoise of Germany displayed extended ellipse size compared to the grey seal. This may be due to a more diverse diet and, perhaps, a more opportunistic foraging behaviour than grey seals. Surprisingly, another group of grey seals sampled at Isle of May, Scotland displayed lower δ15N values and a very small ellipse size compared to grey seals from Germany, presumably being even more selective in their prey choice. Nevertheless, comparing the trophic position of the groups of grey seals requires caution as the isotopic baseline differed between the two sampling areas. This study allowed the determination of the competition, the spatial variations and the trophic niches of marine mammals in the North Sea and will, at the end, evaluate the effects of the changes in the North Sea on the ecology of marine mammals. [less ▲]

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See detailInter-individual differences in contamination profiles as tracer of social group association in stranded sperm whales
Schnitzler, Joseph ULiege; Pinzone, Marianna ULiege; Autenrieth, Marijke et al

in Scientific Reports (2018), 8(10958), 11

Ecological and physiological factors lead to different contamination patterns in individual marine mammals. The objective of the present study was to assess whether variations in contamination profiles ... [more ▼]

Ecological and physiological factors lead to different contamination patterns in individual marine mammals. The objective of the present study was to assess whether variations in contamination profiles are indicative of social structures of young male sperm whales as they might reflect a variation in feeding preferences and/or in utilized feeding grounds. We used a total of 61 variables associated with organic compounds and trace element concentrations measured in muscle, liver, kidney and blubber gained from 24 sperm whales that stranded in the North Sea in January and February 2016. Combining contaminant and genetic data, there is evidence for at least two cohorts with different origin among these stranded sperm whales; one from the Canary Island region and one from the northern part of the Atlantic. While genetic data unravel relatedness and kinship, contamination data integrate over areas, where animals occured during their lifetime. Especially in long-lived animals with a large migratory potential, as sperm whales, contamination data may carry highly relevant information about aggregation through time and space. [less ▲]

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See detailHigh Mercury levels: are Arctic seals “what” or “where” they eat?
Pinzone, Marianna ULiege; Eulaers, Igor; Lepoint, Gilles ULiege et al

Poster (2018, April 19)

In contrast to other regions of the world or even sympatric terrestrial species, Arctic marine predators continue to accumulate increasing levels of Mercury (Hg) in their tissues. Hg bioaccumulation in ... [more ▼]

In contrast to other regions of the world or even sympatric terrestrial species, Arctic marine predators continue to accumulate increasing levels of Mercury (Hg) in their tissues. Hg bioaccumulation in Arctic seals may be linked to their particular life style, or to their extreme physiological adaptations, such as a short period of lactation with very fatty milk. The present study aimed at assessing how dietary resources and hunting distribution influence Hg exposure in Arctic true seals, through the integration of isotopic tracers with Hg levels. Indeed stable Carbon, Nitrogen and Sulfur isotope ratios can be successfully used to study species’ ecology and indicate potential contamination sources. For this reason hair was sampled from free-ranging hooded seal Cystophora cristata (Cc, n = 25) and harp seal Phoca groenlandicus (Pg, n = 36) in the pack ice of the Greenland Sea (near Jan Mayen). Stable isotope ratios were acquired via Isotope Ratio – Mass Spectrometry and used to model stable isotope niches (Standard Ellipses Areas; SEAs). Iterative Bayesian estimations were used to calculate the % of overlap between the ellipses. Total-Hg (T-Hg) concentrations were measured via Atomic absorption spectroscopy. The Cc δ15N-δ13C SEA (3.02‰2) was larger than that of Pg (2.64‰2) in 69% of model runs and did not overlap (22%). This may reflect Cc wide migrations down to warmer sub-Arctic waters compared to Pg that have an exclusively Arctic distribution. Moreover, while Cc hunt for a variety of bentho-pelagic prey (e.g., halibut, redfish, cod and squid) during long dives down to 1000m, Pg feed mostly on pelagic schooling fish between 100 and 400m of depth. The Cc δ15N-δ34S SEA (21‰2) was also larger than that of Pg (16‰2) in 85% of model runs; but this time the ellipses overlapped considerably (52%). Indeed both species presented two distinct groups along the δ34S axis: the most 34S enriched group included adult individuals, while the 34S depleted one included juveniles. This may result from the shallower hunting behavior of juvenile seals and their reliance on ice food webs. Finally, the larger migratory patterns and deep feeding behavior of Cc seem to determine significantly higher levels of T-Hg levels in this species (3.2±3.6 µg g-1) with respect to Pg (1.7±0.9µg g-1; U = 322, P = 0.01), as a consequence of (1) the higher number of Hg sources in sub-Arctic waters and (2) Hg remobilization from the sea bottom and its uptake by benthic food webs. [less ▲]

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See detailApplications of isotope ratio mass spectrometry in aquatic ecosystems at the University of Liège
Sturaro, Nicolas ULiege; Damseaux, France ULiege; Das, Krishna ULiege et al

Poster (2018, March 29)

The use of stable isotopes as ecological tracers through isotope ratio mass spectrometry has a long history at the University of Liège, Belgium. Since at least 35 years, applications of stable isotopes in ... [more ▼]

The use of stable isotopes as ecological tracers through isotope ratio mass spectrometry has a long history at the University of Liège, Belgium. Since at least 35 years, applications of stable isotopes in aquatic ecosystems have been developed within the Laboratory of Oceanology and the Laboratory of Animal Systematic and Diversity. One research axis is the measurement of stable isotope composition (carbon, nitrogen and sulfur) in organic matter to delineate food web structure and to study animal diet, their trophic niches and their alteration by human activities. This approach assumes that the isotopic composition of a consumer (i.e. the 13C/12C, 15N/14N and 34S/32S ratios) is a proportional mix of the isotopic compositions of its food sources, with a slight enrichment towards the heavier isotope. We have successively applied this approach in different marine and freshwater habitats and ecosystems (e.g. seagrass meadows, macrophytodetritus accumulations, Antarctic benthic systems and coral reefs), in polar, temperate and tropical areas. Mediterranean food web and fish trophic ecology have received a peculiar attention. Furthermore, it has been applied to marine mammals, marine turtles, crocodilian species, Mediterranean and Antarctic benthic invertebrates, and the study of symbiotic associations (fish-sea cucumbers, tropical echinoderms and hydrothermal crustaceans). Stable isotope labelling is also used in our laboratory to study and quantify various ecological processes such as inorganic nitrogen incorporation and trophic transfers. Coupling between trophic ecology and ecotoxicology is another area of investigation. The laboratory’s facilities, renewed in 2012 and managed by Dr Gilles Lepoint, are composed of an elemental analyser and a gas chromatography coupled to an isotope ratio mass spectrometer. The gas chromatography is also equipped with a quadrupole mass spectrometer. More recently, the laboratory has been attempting to develop the measurement of stable isotope ratios of specific compounds such as amino acids, which should allow to determine more precisely the trophic position of consumers. Overall, here we aim to provide insights into the use of isotope ratio mass spectrometry and illustrate their utility and potential applications to better understand food web structures and species diet in aquatic ecosystems. [less ▲]

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See detailEcotoxicological biomarkers and accumulation of contaminants in pinnipeds
Lehnert, Kristina; Desforges, Jean-Pierre; Das, Krishna ULiege et al

in Fossi, Maria; Panti, Christina (Eds.) Marine mammal ecotoxicology: Impacts of Multiple Stressors on Population Health (2018)

Pinnipeds are long-lived predators with amphibious lifestyles, often residing in remote environments. Environmental contaminants as well as other stressors due to anthropogenic impacts into their habitat ... [more ▼]

Pinnipeds are long-lived predators with amphibious lifestyles, often residing in remote environments. Environmental contaminants as well as other stressors due to anthropogenic impacts into their habitat are known to affect the immune and endocrine system in seals and to affect marine mammal health status and increase their susceptibility to infectious disease. Pinnipeds are under a continuous pressure of anthropogenic activities such as fisheries, ship traffic, oil exploration, and chemical and noise pollution. This has prompted many studies over the past decades to evaluate the effects of cumulative stress on the health of these marine mammals. Different approaches have been used to assess the effects of contaminants on the health of marine mammals and better understand the impact on their physiology. To evaluate detrimental changes potentially caused by xenobiotics on wildlife health, parameters of biological processes with prognostic or diagnostic explanatory power, so called biomarkers need to be found. An overview about parameters used as markers to measure exposure and effects is given in the following chapter, combining long-standing, established methods with new techniques that are promising future tools. [less ▲]

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See detailUse of multielement stable isotope ratios to investigate ontogenetic movements of Micropogonias furnieri in a tropical Brazilian estuary
Pizzochero, Ana Carolina; Michel, Loïc ULiege; Chenery, Simon et al

in Canadian Journal of Fisheries and Aquatic Sciences (2018), 75(6), 977-986

The whitemouth croaker, Micropogonias furnieri, is a long-lived fish of high commercial importance in the Western Atlantic Ocean. Here, we used stable isotope ratios of carbon, sulfur and nitrogen and ... [more ▼]

The whitemouth croaker, Micropogonias furnieri, is a long-lived fish of high commercial importance in the Western Atlantic Ocean. Here, we used stable isotope ratios of carbon, sulfur and nitrogen and isotopic niche metrics (SIBER) to study feeding habits and track habitat use by whitemouth croakers in Guanabara Bay, an estuary in Rio de Janeiro state, Brazil. Our results highlighted size-related habitat segregation, with small juvenile (< 30 cm) fishes residing mostly inside estuaries, while large adult (> 60 cm) fishes feed mainly in Continental Shelf (CS) waters. Medium adult fishes (30-60 cm) appear to feed in multiple coastal and CS habitats. Moreover, their feeding ecology showed strong temporal differences, linked with seasonal and, to a lesser extent, inter-annual variation in oceanographic features of the ecosystem in which they live. Overall, these differences in ecological features suggest that (1) adult and juvenile whitemouth croakers should be treated as different components of the food web and (2) the conservation of these habitats should be prioritized to better manage and sustain the coastal fisheries in Guanabara Bay. [less ▲]

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See detailTranscriptional effects of phospholipid fatty acid profile on rainbow trout liver cells exposed to methylmercury
Ferain, Aline; Bonnineau, Chloé; Neefs, Inneke et al

in Aquatic Toxicology (2018), 199

Lipids, and their constitutive fatty acids, are key nutrients for fish health as they provide energy, maintain cell structure, are precursors of signalling molecules and act as nuclear receptor ligands ... [more ▼]

Lipids, and their constitutive fatty acids, are key nutrients for fish health as they provide energy, maintain cell structure, are precursors of signalling molecules and act as nuclear receptor ligands. These specific roles may be of crucial importance in a context of exposure to pollutants. We recently showed that the fatty acid profile of rainbow trout liver cell phospholipids modulates sensitivity to an acute methylmercury challenge. In order to investigate mechanisms of effects, we herein tested whether specific polyunsaturated fatty acids may protect cells from methylmercury through decreasing intracellular mercury accumulation and/or enhancing cellular defences (e.g. via modulation of gene expression patterns). We also investigated the inverse relationship and assessed the impact of methylmercury on cellular fatty acid metabolism. To do so, the fatty acid composition of rainbow trout liver cell phospholipids was first modified by incubating them in a medium enriched in a specific polyunsaturated fatty acid (PUFA) from either the n-3 family (alpha-linolenic acid, ALA; eicosapentaenoic acid, EPA) or the n-6 family (linoleic acid, LA; arachidonic acid, AA). Cells were then exposed to methylmercury (0.15 or 0.50 μM) for 24 h and sampled thereafter for assessing phospholipid fatty acid profile, intracellular total mercury burden, and expression pattern of genes involved in fatty acid metabolism, synthesis of polyunsaturated fatty acid-derived signalling molecules and stress response. We observed that cells incorporated the given polyunsaturated fatty acid and some biotransformation products in their phospholipids. MeHg had few impacts on this cellular phospholipid composition. None of the PUFA enrichments affected the cellular mercury burden, suggesting that the previously observed cytoprotection conferred by ALA and EPA was not linked to a global decrease in cellular accumulation of mercury. Fatty acid enrichments and methylmercury exposure both modulated gene expression patterns. Genes involved in the synthesis of polyunsaturated fatty acid-derived signalling molecules, in stress response and the orphan cytochrome P450 20A1 were identified as possible sites of interaction between fatty acids and methylmercury in rainbow trout liver cells. [less ▲]

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See detailA meta-analysis of isotopic compositions of North Sea marine mammals
Damseaux, France ULiege; Lepoint, Gilles ULiege; Pomeroy, Paddy et al

Poster (2017, October)

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See detailTrace elements in feathers and blood of Antarctic seabirds
Padilha, Janeide; Souza, J; de Almeida, A et al

Poster (2017, September 08)

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See detailCarbon, Nitrogen and Sulphur isotopic fractionation in captive juvenile hooded seal (Cystophora cristata): application for diet analysis
Pinzone, Marianna ULiege; Acquarone, Mario; Huyghebaert, Loreen ULiege et al

in Rapid Communications in Mass Spectrometry (2017), 31

Rationale: Intrinsic biogeochemical markers, such as stable isotope ratios of carbon, nitrogen and sulphur are increasingly used to trace the trophic ecology of marine top predators. However, insufficient ... [more ▼]

Rationale: Intrinsic biogeochemical markers, such as stable isotope ratios of carbon, nitrogen and sulphur are increasingly used to trace the trophic ecology of marine top predators. However, insufficient knowledge of fractionation processes in tissues continues to hamper the use of these markers.Methods: We performed a controlled feeding experiment with eight juvenile hooded seals (Cystophora cristata) that were held on a herring-based diet (Clupea harengus) for two years. Stable isotope ratios were measured via isotope ratio mass spectrometry in three of their tissues and related to values of these markers in their diet. Results: Diet-tissue isotope enrichment (trophic enrichment factor, TEF) values between dietary herring and seal tissues for carbon (Δ13C) were + 0.7 ‰ for red blood cells, + 1.9 ‰ for hair and + 1.1 ‰ for muscle. The TEFs for nitrogen trophic (Δ15N) were + 3.3 ‰ for red blood cells, + 3.6 ‰ for hair and + 4.3 ‰ for muscle. For sulphur, the Δ34S values were +1.1 ‰ for red blood cells, + 1.0 ‰ for hair and + 0.9 ‰ for muscle.Conclusions: These enrichment values were greater than those previously measured in adult seals. This increase may be related to the higher rate of protein synthesis and catabolism in growing animals. This study is the first report on sulphur isotope enrichment values for a marine mammal species. [less ▲]

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See detailTrace elements and organochlorines in sperm whales stranded on the coast of Schleswig Holstein in 2016
Pinzone, Marianna ULiege; Schnitzler, Joseph ULiege; Thomé, Jean-Pierre ULiege et al

Poster (2017, May 02)

Several strandings of sperm whales occurred in the North Sea during January and February 2016. Twelve animals were necropsied and sampled after their discovery on German coasts of Schleswig Holstein ... [more ▼]

Several strandings of sperm whales occurred in the North Sea during January and February 2016. Twelve animals were necropsied and sampled after their discovery on German coasts of Schleswig Holstein. Muscle, liver, kidney and blubber samples were taken from all specimens for toxicological analyses. The concentrations of lipophilic organic pollutants such as polychlorinated biphenyl (PCB) and pesticides such as DDT were determined in adipose tissue. Metals and trace elements such as cadmium, selenium and mercury were measured in the liver, kidney and muscle. Polychlorinated biphenyls (PCBs) and pesticides such as DDTs were determined in adipose tissue at levels of 0.9 and 1.3 mg.kg-1 lipid weight respectively. Cadmium, selenium and mercury were measured in the liver at respective concentrations of 57, 52 and 81 mg.kg-1 dry weight. The investigated 12 sperm whales stranded on the coasts of Schleswig Holstein in spring 2016 showed a lower contamination of organic pollutants than the 7 sperm whales stranded along the Belgian and Dutch coast in the winter of 1994/95. These animals were clearly larger and older than the ones that stranded in Schleswig-Holstein. So, lower contaminant burden may be due to shorter life span. It seems unlikely that contamination is the direct cause of the death of sperm whales. However, debilitating role of pollutants cannot be excluded, as strandings are often a multi factorial event. Further investigations on the contaminant patterns among the 30 sperm whales at different stranding sites may also give indications on the feeding strategy and linkage among the individuals. [less ▲]

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See detailTrophic ecology of marine mammals in the North Sea
Damseaux, France ULiege; Lepoint, Gilles ULiege; Das, Krishna ULiege

Conference (2017, March 03)

For over a decade, the North Sea has been undergoing significant changes due to global changes and overfishing. We conducted meta-analyses of previously published data on marine mammals sampled in the ... [more ▼]

For over a decade, the North Sea has been undergoing significant changes due to global changes and overfishing. We conducted meta-analyses of previously published data on marine mammals sampled in the North Sea to test the competition for food sources and spatial variations. The overall objective of this study was to assess the potential trophic changes of the grey seal, the harbour seal and the harbour porpoise. Data included δ13C and δ15N values measured in blood cells and muscles from the three species. SIBER, a trophic niche overlap quantification approach, highlighted potential competition between marine mammal species. The ellipse drawn for harbour seal data showed the highest δ15N values, reflecting its trophic position at the top of the food web. But the ellipse overlapping between the harbour seal and the grey seal of Germany was very important, showing a potential strong competition for food sources may be due to the overfishing. The harbour porpoise displayed a lower trophic position and a wide range of δ13C and δ15N values compared to harbour seal and grey seal as seen from its extended ellipse size. This may be due to a more opportunistic behaviour following the decline of some fish population in the North Sea. Surprisingly a group of grey seals sampled in Scotland present a very small ellipse size, presumably more selective in their prey choice, and showed the lowest δ15N values. Caution should be taken before comparing the trophic position of the groups of grey seals as the baseline differed between the two sampling areas. Low nitrates concentrations, higher latitudes, colder temperatures, deeper waters and rocky soils of the Scotland’s coasts of the North Sea cause a stratification phenomenon of the water column explaining the lower δ15N baseline in this area and so the spatial variation between these two groups of grey seals living in the North Sea. [less ▲]

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See detailMercury stable isotopes discriminate different populations of common Seabass around Europe and provide insight on mercury cycle
Cransveld, Alice ULiege; Das, Krishna ULiege

Conference (2017, March 03)

In a context where worldwide emission of mercury, a global pollutant, are increasing, research for new tools and data enabling a deeper understanding of mercury fluxes and sources are crucial. Over the ... [more ▼]

In a context where worldwide emission of mercury, a global pollutant, are increasing, research for new tools and data enabling a deeper understanding of mercury fluxes and sources are crucial. Over the past few years, the analysis of stable isotopes of mercury has emerged as a new promising technique affording to explore the Hg cycle, somewhat like what is being done for the carbon and nitrogen cycles. Hg can exhibit both mass-dependent (MDF, δ202Hg) and mass-independent fractionation (MIF, Δ199Hg). While MDF may occur during biological cycling inter alia and could be used to understand bioaccumulation processes, MIF provides a unique fingerprint of specific chemical pathways, such as photochemical transformations. In this context, information provided by Hg isotopes would help to improve environmental management strategies. However, so far, few studies considered Hg isotopes in marine vertebrates. Our study reports the first data on Hg isotopic composition in marine European fish, for seven distinct populations of the common seabass, Dicentrarchus labrax. The combination of δ202Hg and Δ199Hg values enabled us to successfully discriminate several populations and recursive partitioning analyses demonstrated their relevance as discriminating tools. Moreover, mercury isotopic values provided insight on Hg contamination sources for biota and on MeHg cycling. We showed that δ202Hg in seabass muscle is probably a good integration of the δ202Hg of MeHg in their diet, except when concentrations are low, in which case in vivo processes would significantly influence the δ202Hg in fish muscle. The δ202Hg was also linked with known Hg point sources in several sites and the overall range of δ202Hg around Europe was suggested to be related to global atmospheric contamination. Δ199Hg in seabass was shown to reflect the level of contamination of fish and their habitat but not only. MIF was also clearly influenced by ecological characteristics of fish and their habitats, and therefore could be used to identify and investigate peculiar Hg environments such as in the Black Sea. Throughout this study, results from the Black Sea population stood out, underlying the particularities of Black Sea Hg which seemed to display a Hg cycling similar to what is observed in fresh water lakes. Data on Hg sources and levels in Europe are scarce and Hg cycling is still poorly understood. Our findings constitute the first large scale isotopic analyses of Hg in the area. They bring out the possibility to use mercury isotopes in order to discriminate distinct populations, to explore the global Hg cycle on a large scale (Europe) and to identify particularities in the Hg cycle of several sites. The interest of using mercury isotopes to investigate the whole European Hg cycle is clearly highlighted by our results. [less ▲]

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