Publications of Krishna Das
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See detailUse of multi-element 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 & Aquatic Sciences (in press)

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 detailMercury stable isotopes discriminate different populations of European seabass and trace potential Hg sources around Europe
Cransveld, Alice; Amouroux, David; Tessier, Emmanuel et al

in Environmental Science & Technology (in press)

Our study reports the first data on mercury (Hg) isotope composition in marine European fish, for seven distinct populations of the European seabass, Dicentrarchus labrax. The use of δ20230 Hg and Δ19931 ... [more ▼]

Our study reports the first data on mercury (Hg) isotope composition in marine European fish, for seven distinct populations of the European seabass, Dicentrarchus labrax. The use of δ20230 Hg and Δ19931 Hg values in SIBER enabled us to estimate Hg isotopic niches, successfully discriminating several populations. Recursive-partitioning analyses demonstrated the relevance of Hg stable isotopes as discriminating tools. Hg isotopic values also provided insight on Hg contamination sources for biota in coastal environment. The overall narrow range of δ202 Hg around Europe was suggested to be related to a global atmospheric contamination while δ202 Hg at some sites was linked either to background ontamination, or with local contamination sources. Δ199 Hg was related to Hg levels of fish but we also suggest a relation with ecological conditions. Throughout this study, results from the Black Sea population stood out, displaying a Hg cycling similar to fresh water lakes. Our findings bring out the possibility to use Hg isotopes in order to discriminate distinct populations, to explore the Hg cycle on a large scale (Europe) and to distinguish sites contaminated by global versus local Hg source. The interest of using Hg sable isotopes to investigate the whole European Hg cycle is clearly highlighted. [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 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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See detailA meta-analysis of isotopic compositions of North Sea marine mammals
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 detailPost-embryonic development of sheepshead minnow Cyprinodon variegatus: a staging tool based on externally visible anatomical traits
Schnitzler, Joseph ULiege; Dussenne, Mélanie ULiege; Frederich, Bruno ULiege et al

in Ichthyological Research (2017), 64

The sheepshead minnow Cyprinodon variegatus has become a favoured model for laboratory studies because of their small size, rapid development, and tolerance of laboratory conditions. Here, we analyse ... [more ▼]

The sheepshead minnow Cyprinodon variegatus has become a favoured model for laboratory studies because of their small size, rapid development, and tolerance of laboratory conditions. Here, we analyse sheepshead minnow post-embryonic development with the goal of providing a generally useful method for staging fish after embryogenesis. Groups of three females and two males were placed in breeding chambers designed for this experiment. More than 100 eggs were collected and maintained in seawater. Embryos were selected under a dissection microscope and placed in incubation dishes (50 per dish) at 26 °C. On day six, embryos hatched and larvae were transferred to 1 L beakers. To define a simplified normalization table for sheepshead minnow development, we measured each fish for its standard length and examined the fish for four externally evident traits: pigmentation pattern, caudal fin morphology, anal fin morphology, and dorsal fin morphology. The four traits were chosen, because they are easily visualized with standard laboratory equipment such as the stereomicroscope and camera. We have provided criteria for staging sheepshead minnows in studies of post-embryonic development. Our data suggest that dorsal and anal fin morphology may serve as a useful phenotype for defining metamorphic climax stages throughout post-embryonic development in C. variegatus. The staging systems we propose should facilitate detailed anatomical and developmental analyses in relation to ecotoxicological studies on potential disruption of the thyroid axis by xenobiotics and endocrine-disrupting compounds. [less ▲]

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See detailMorphology of the filtration apparatus of three planktivorous fishes and relation with ingested anthropogenic particles
Collard, France ULiege; Gilbert, Bernard ULiege; Eppe, Gauthier ULiege et al

in Marine Pollution Bulletin (2017)

Anthropogenic particles (APs), including microplastics, are ingested by a wide variety of marine organisms. Exposure of Clupeiformes (e.g. herrings, anchovies, sardines) is poorly studied despite their ... [more ▼]

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

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See detailLinking pollutant exposure of humpback whales breeding in the Indian Ocean to their feeding habits and feeding areas off Antarctica
Das, Krishna ULiege; Malarvannan, Govindan; Dirtu, Alin et al

in Environmental Pollution (2017), 220

Humpback whales, Megaptera novaeangliae, breeding off la Reunion Island (Indian Ocean) undergo large-scale seasonal migrations between summer feeding grounds near Antarctica and their reproductive winter ... [more ▼]

Humpback whales, Megaptera novaeangliae, breeding off la Reunion Island (Indian Ocean) undergo large-scale seasonal migrations between summer feeding grounds near Antarctica and their reproductive winter grounds in the Indian Ocean. The main scope of the current study was to investigate chemical exposure of humpback whales breeding in the Indian Ocean by providing the first published data on this breeding stock concerning persistent organic pollutants (POPs), namely polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), DDT and its metabolites (DDTs), chlordane compounds (CHLs), polybrominated diphenyl ethers (PBDEs), and methoxylated PBDEs (MeO-PBDEs). Analyses of stable isotopes δ13C and δ15N in skin resulted in further insight in their feeding ecology, which was in agreement with a diet focused mainly on low trophic level prey species, such as krill from Antarctica. POPs were measured in all humpback whales in the order of HCB > DDTs > CHLs > HCHs > PCBs > PBDEs > MeO-BDEs. HCB (median: 24 ng.g-1 lw) and DDTs (median: 7.7 ng.g-1 lw) were the predominant compounds in all whale biopsies. Among DDT compounds, p,p’-DDE was the major organohalogenated pollutant, reflecting its long-term accumulation in humpback whales. Significantly lower concentrations of HCB and DDTs were found in females than in males (p<0.001). Other compounds were similar between the two genders (p>0.05). Differences in the HCB and DDTs suggested gender-specific transfer of some compounds to the offspring. POP concentrations were lower than previously reported results for humpback whales sampled near the Antarctic Peninsula, suggesting potential influence of their nutritional status and may indicate different exposures of the whales according to their feeding zones. Further investigations are required to assess exposure of southern humpback whales throughout their feeding zones. [less ▲]

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See detailSpatial variation in the accumulation of POPs and mercury in bottlenose dolphins of the Lower Florida Keys and the coastal Everglades (South Florida)
Damseaux, France ULiege; Kiszka, J.; Heithaus, M.R. et al

in Environmental Pollution (2017), 220

The bottlenose dolphin (Tursiops truncatus) is an upper trophic level predator and the most common cetacean species found in nearshore waters of southern Florida, including the Lower Florida Keys (LFK ... [more ▼]

The bottlenose dolphin (Tursiops truncatus) is an upper trophic level predator and the most common cetacean species found in nearshore waters of southern Florida, including the Lower Florida Keys (LFK) and the Florida Coastal Everglades (FCE). The objective of this study was to assess contamination levels of total mercury (T-Hg) in skin and persistent organic pollutants (PCBs, PBDEs, DDXs, HCHs, HCB, Σ PCDD/Fs and Σ DL-PCBs) in blubber samples of bottlenose dolphins from LFK (n = 27) and FCE (n = 24). PCBs were the major class of compounds found in bottlenose dolphin blubber and were higher in individuals from LFK (Σ 6 PCBs LFK males: 13421 ± 7730 ng.g-1 lipids, Σ 6 PCBs LFK females: 9683 ± 19007 ng.g-1 lipids) than from FCE (Σ 6 PCBs FCE males: 5638 ng.g-1 ± 3627 lipids, Σ 6 PCBs FCE females: 1427 ± 908 ng.g-1 lipids). These levels were lower than previously published data from the southeastern USA. The Σ DL-PCBs were the most prevalent pollutants of dioxin and dioxin like compounds (Σ DL-PCBs LFK: 739 ng.g-1 lipids, Σ DL-PCBs FCE: 183 ng.g-1 lipids) since PCDD/F concentrations were low for both locations (mean 0.1 ng.g-1 lipids for LFK and FCE dolphins). The toxicity equivalences of PCDD/Fs and DL-PCBs expressed as TEQ in LFK and FCE dolphins is mainly expressed by DL-PCBs (81% LFK - 65% FCE). T-Hg concentrations in skin were significantly higher in FCE (FCE median 9314 ng.g-1 dw) compared to LFK dolphins (LFK median 2941 ng.g-1 dw). These bottlenose dolphins concentrations are the highest recorded in the southeastern USA, and may be explained, at least partially, by the biogeochemistry of the Everglades and mangrove sedimentary habitats that create favourable conditions for the retention of mercury and make it available at high concentrations for aquatic predators. [less ▲]

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See detailIsotopic compositions of North Sea marine mammals
Damseaux, France ULiege; Pomeroy, Paddy; Sierbert, Ursula et al

Poster (2017)

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

For over a decade, the North Sea has been undergoing significant changes due to global changes and overfishing. We conducted meta-analyses on marine mammals sampled in the North Sea to test the potential impact of changes in fish stocks 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 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)

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 detailIsotopic niches of Fin Whales from the Mediterranean Sea and the Celtic sea (North Atlantic)
Das, Krishna ULiege; Holleville, Ophélie; Ryan, Conor et al

in Marine Environmental Research (2017), 127

The fin whale (Balaenoptera physalus) is the most abundant and widespread mysticete species in the Mediterranean Sea, found mostly over deep, offshore waters of the western and central portion of the ... [more ▼]

The fin whale (Balaenoptera physalus) is the most abundant and widespread mysticete species in the Mediterranean Sea, found mostly over deep, offshore waters of the western and central portion of the region. In the Mediterranean, this species is known to feed mainly on krill, in contrast to its Atlantic counterpart, which displays a more diversified diet. The International Whaling Commission recognizes several managements units in the Atlantic and the Mediterranean Sea and the connectivity between these populations is still being debated. Questions remain about inter-individual feeding strategies and trophic ecology. The goal of this study was to compare isotopic niches of fin whales from the Mediterranean Sea and the Celtic Sea (North Atlantic). δ13C and δ15N values were analysed in 136 skin biopsies from free-ranging Mediterranean fin whales sampled in 2010 and 2011 during campaigns at sea. δ13C and δ15N values ranged from -20.4 to -17.1 ‰ and from 5.9 to 8.9 ‰, respectively. These values are in good agreement with those estimated previously from baleen plates from Mediterranean and North Atlantic fin whales. The narrow isotopic niche width of the Mediterranean fin whale (Standard Ellipses area SEAc) compared to the North Atlantic fin whale raises many concerns in the context of global changes and long-term consequences. One could indeed expect that species displaying narrow niches would be more susceptible to ecosystem fragmentation and other anthropogenic impacts. [less ▲]

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See detailMetals as chemical tracers to discriminate ecological populations of threatened Franciscana dolphins (Pontoporia blainvillei) from Argentina
Romero, M.B.; Polizzi, P.; Chiodi, L. et al

in Environmental Science and Pollution Research (2017), 24(4), 3940-3950

Franciscana dolphins are the most impacted small cetacean in the Southwestern Atlantic Ocean, classified as Vulnerable A3d by IUCN. Essential (Fe, Mo, Mn, Cr, Ni, Co) and non-essential (Ag, Pb, Sn) trace ... [more ▼]

Franciscana dolphins are the most impacted small cetacean in the Southwestern Atlantic Ocean, classified as Vulnerable A3d by IUCN. Essential (Fe, Mo, Mn, Cr, Ni, Co) and non-essential (Ag, Pb, Sn) trace elements (TEs) were measured in liver, kidney, and brain samples of by-catch Franciscana dolphins that were living in estuarine (n = 21) and marine (n = 21) habitats (1) to assess whether TEs posed a threat and (2) to evaluate the suitability of TEs for discriminating ecological populations of this species in Argentinean waters. Essential TEs showed little variation in tissues from both groups in agreement with levels reported for other cetaceans and suggesting that these concentrations correspond to normal physiological levels. Non-essential TEs were higher in estuarine juveniles and adults dolphins than in marine specimens. These results suggest anthropogenic sources associated with estuarine area and that Franciscana dolphins are good sentinels of the impact of the environment. The difference in the concentrations of TEs beetwen ecological populations appeared to be related to distinct exposures in both geographical areas, and it is suggested that Ag and Sn concentrations in adults are good chemical tracers of anthropogenic input of TEs. These results provide additional information for improved management and regulatory policy. [less ▲]

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See detailExploitation of coastal fish communities by harbour porpoises Phocoena phocoena during nursing periods in German Baltic waters.
Pinzone, Marianna ULiege; Michel, Loïc ULiege; Gallus, Anja et al

Conference (2016, December 11)

Baltic sub-populations of harbour porpoises Phocoena phocoena meet in in Southwestern waters in Spring when females reach the coastal areas for calving and nursing. In Autumn they separate again for ... [more ▼]

Baltic sub-populations of harbour porpoises Phocoena phocoena meet in in Southwestern waters in Spring when females reach the coastal areas for calving and nursing. In Autumn they separate again for reproduction : the Belt sea populations westwards in the Kattegat/Skarregat region, the Baltic proper population northwards in the central basin. The increased number of juvenile and newborn strandings along the German Baltic coasts give evidence for a possible existence of local calving grounds in this area. Calving and nursing habitats are the most important areas for management purposes. This project aimed to describe inhabitancy and diet of females and calves along the German Baltic coast, in order to achieve effective conservation measures. Nitrogen, carbon and, for the first time, sulphur stable isotopes (δ13C, δ15N and δ34S) were analysed in coastal species of fish and invertebrates in spring, autumn and winter 2015/2016 and in four different areas, to assess for seasonal and geographical variation of porpoises habitat use. The structure of ecological niches was inferred within and between communities using the SIBER model, and was compared to results from stomach content analysis. N, C and S values of fish and invertebrates strongly varied, seasonally and geographically, as a consequence of environmental factors characteristic of each sampling area. Additionally, each species presented large isotopic variability, suggesting possible intraspecific dietary specialisations. Females δ13C and δ34S signatures integrated both open-waters and coastal feeding, while juveniles presented a more coastal distribution. The absence of difference in δ15N values between age classes confirmed persistence of milk assimilation from the mothers. Niches structures and overlaps and stomach content analysis suggested gobies (Potamoschistus spp and Neogobius spp in particular), crabs and small coastal fish (ex. three-spined stickleback) as the main preys of juveniles. The integration of all three stable isotopes together permitted to well delineate even the highly dynamic food web of the Baltic German waters, confirming the use of sulphur isotopes in marine ecological studies. [less ▲]

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See detailMicroplastics Contamination in Three Planktivorous and Commercial Fish Species
Collard, France ULiege; Das, Krishna ULiege; Gilbert, Bernard ULiege et al

in Fate and Impact of Microplastics in Marine Ecosystems - From the Coastline to the Open Sea (2016, December 02)

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See detailTriclosan exposure results in alterations of thyroid hormone status and retarded early development and metamorphosis in Cyprinodon variegatus
Schnitzler, Joseph ULiege; Frederich, Bruno ULiege; Dussenne, Mélanie ULiege et al

in Aquatic Toxicology (2016), 181

Thyroid hormones are critically involved in somatic growth, development and metamorphosis of vertebrates. The structural similarity between thyroid hormones and triclosan, an antimicrobial compound widely ... [more ▼]

Thyroid hormones are critically involved in somatic growth, development and metamorphosis of vertebrates. The structural similarity between thyroid hormones and triclosan, an antimicrobial compound widely employed in consumer personal care products, suggests triclosan can have adverse effects on the thyroid system. The sheepshead minnow, Cyprinodon variegatus, is now used in ecotoxicological studies that have recently begun to focus on potential disruption of the thyroid axis by endocrine disrupting compounds. Here, we investigate the in vivo effects of exposure to triclosan (20, 50, and 100 μg L−1) on the thyroid system and the embryonic and larval development of C. variegatus. Triclosan exposure did not affect hatching success, but delayed hatching time by 6–13 h compared to control embryos. Triclosan exposure affected the ontogenetic variations of whole body thyroid hormone concentrations during the larval phase. The T3 peak around 12–15 dph, described to be indicative for the metamorphosis climax in C. variegatus, was absent in triclosan-exposed larvae. Triclosan exposure did not produce any deformity or allometric repatterning, but a delayed development of 18–32 h was observed. We conclude that the triclosan-induced disruption of the thyroid system delays in vivo the start of metamorphosis in our experimental model. We observed a global developmental delay of 24–45 h, equivalent to 4–7% prolongation of the developmental time in C. variegatus. The costs of delayed metamorphosis can lead to reduction of juvenile fitness and could be a determining factor in the outcome of competitive interactions. [less ▲]

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See detailEVALUATION OF FISH EXPOSURE TO POP-LIKE (ORGANOTIN) COMPOUNDS IN SEPETIBA BAY (RIO DE JANEIRO STATE, BRAZIL) THROUGH HEPATIC TOTAL TIN CONCENTRATIONS
Paiva, TC; Schilithz, PF; Bisi, TL et al

in Organohalogen Compounds (2016, August)

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See detailMicroplastics contamination in three planktivorous and commercial fish species
Collard, France ULiege; Das, Krishna ULiege; Gilbert, Bernard ULiege et al

Poster (2016, May)

In 2014, 311 million tonnes of plastics were produced worldwide while it is estimated that 10% ended up in the oceans. Plastics adsorb many pollutants, cause entanglements in many vertebrates and provoke ... [more ▼]

In 2014, 311 million tonnes of plastics were produced worldwide while it is estimated that 10% ended up in the oceans. Plastics adsorb many pollutants, cause entanglements in many vertebrates and provoke blockage of the digestive tract of marine mammals, birds and turtles. Plastics also fragment in smaller parts, forming microplastics (<5 mm). These microplastics have the same size than planktonic organisms and can thus be ingested by filter-feeders and planktivorous organisms including fish. Although planktivorous Clupeiforme species are the most fished species in the world (17 million tonnes in 2013), the possible impact of microplastic ingestion on this group has received little attention. The aim of this study was to quantify and to characterize the ingested anthropogenic particles (AP) in herrings (Clupea harengus), sardines (Sardina pilchardus) and anchovies (Engraulis encrasicolus). Twenty individuals of each species were sampled. Herrings and sardines were caught in the Channel and in the North Sea in January 2013 and in January 2014. Anchovies were sampled in July 2013. The stomach contents were digested by sodium hypochlorite to isolate AP and then they were analysed by Raman spectroscopy and measured. AP were constituted of microplastics (MP) and cellulose fibres, sometimes associated with dyes. We found several plastic families: polyethylene (PE), polypropylene (PP), polystyrene, polyacrylonitrile, polyethylene terephthalate, polyamide and poly(butyl methacrylate). MP occurred in 35%, 50% and 40% of stomach contents of anchovies, sardines and herrings, respectively. Anchovies ingested bigger AP (2 mm) than the two other species. MP was in majority PE followed by PP. Our study shows that highly commercial species are exposed to MP. Further research is needed as MP are transport medium for organic pollutants and their fate once in the organism is unknown. [less ▲]

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See detailContrasted accumulation patterns of persistent organic pollutants and mercury in sympatric tropical dolphins from the south-western Indian Ocean
Dirtu, Alin; Malavannan, Govindan; Das, Krishna ULiege et al

in Environmental Research (2016), 146

Due to their high trophic position and long life span, small cetaceans are considered as suitable bioindicators to monitor the presence of contaminants in marine ecosystems. Here, we document the ... [more ▼]

Due to their high trophic position and long life span, small cetaceans are considered as suitable bioindicators to monitor the presence of contaminants in marine ecosystems. Here, we document the contamination with persistent organic pollutants (POPs) and total mercury (T-Hg) of spinner (Stenella longirostris, n=21) and Indo-Pacific bottlenose dolphins (Tursiops aduncus, n=32) sampled from the coastal waters of La Réunion (south-western Indian Ocean). In addition, seven co-occurring teleost fish species were sampled and analyzed as well. Blubber samples from living dolphins and muscle from teleosts were analyzed for polychlorinated biphenyls (PCBs), DDT and metabolites (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). Methoxylated PBDEs (MeO-PBDEs), reported as having a natural origin, were also analyzed. T-Hg levels were measured in blubber and skin biopsies of the two living dolphin species. δ13C and δ15N values were determined in skin of the dolphins and in the muscle of teleosts. For PCBs, HCHs and T-Hg, concentrations were significantly higher in T. aduncus than in S. longirostris. For other POP levels, intra-species variability was high. MeO-PBDEs were the dominant compounds (55% of the total POPs) in S. longirostris, while PCBs dominated (50% contribution) in T. aduncus. Other contaminants showed similar profiles between the two species. Given the different patterns of POPs and T-Hg contamination and the stable isotope composition observed among analyzed teleosts, dietary and foraging habitat preferences possibly explain the contrasted contaminant profiles observed in the two dolphin species. Levels of each class of contaminants were significantly higher in males than females. Despite their spatial and temporal overlap in the waters of La Réunion, S. longirostris and T. aduncus are differently exposed to contaminant accumulation. [less ▲]

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See detailDistribution of inorganic and organic contaminants in the intertidal surface sediments along the Hugli River Estuary, eastern part of India
Das, Krishna ULiege; Sarkar, Santosh; Thomé, Jean-Pierre ULiege et al

Conference (2016, February 17)

Hooghly estuary and coastal environment in north east coast of India has been strongly affected by the rapid human settlements, intensive boating and tourist activities, deforestation and ongoing ... [more ▼]

Hooghly estuary and coastal environment in north east coast of India has been strongly affected by the rapid human settlements, intensive boating and tourist activities, deforestation and ongoing agricultural and aquacultural practices. The present work investigated trace elements (TEs, T-Hg, Al, V, Cr, Fe, Mn, Cu, Zn, Co, Ni, Ca, Sr, Li, Be, P, Mo, Ag, Cd, Sn, Sb, Ba, Pb, Bi, U, As, Se) and organohalogen compounds in surface sediment (top 0-10cm) considering 8 sampling sites along the Hugli River Estuary (HRE), India. The studied organic compounds include polychlorobiphenyls (PCBs), hexachlorocyclohexane isomers (HCHs), dichlorodiphenyltrichloroethane and metabolites (DDTs) and polybromodiphenyl ethers (PBDEs). Textural analyses of the sediment reveal an overall dominance of mud. All trace elements could be detected at variable concentrations in the following descending order: Al>Fe>Ca> P>Mn> Cu> Zn> Ba >V >Cr>Sr>Ni> Li >Co >Pb>As >Se >U >Be >Sn>Bi >Ag >Mo >Cd >Sb. A synchronous enrichment of majority of the elements were observed at the site Gangasagar (~100 km south megacity Calcutta), situated at the confluence of Hugli River and Bay of Bengal, which might be attributed to cumulative impact of the physicochemical processes and multiple anthropogenic sources. It is revealed that PCBs and DDTs were the dominant compounds among the organic pollutants accounting concentrations up to 23.5 ng.g-1 and 4.4 ng.g-1 respectively at the site Babughat, adjacent to the megacity Calcutta. The results have implications for pollution in complex estuarine environment in a meso-macrotidal setup where there is significant influx of sediments carrying huge load of inorganic and organic pollutants mainly due to rapid urbanization and industrialization. [less ▲]

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