Feeding ecology of five commercial shark species of the Celtic Sea through stable isotope and trace metal analysis.

In order to trace their feeding habits, stable carbon and nitrogen isotope ratios (delta15N and delta13C), as well as trace metal concentrations (Zn, Cd, Fe, Cu, Se and Hg) were analysed in the tissues of five commercial shark species from the Celtic Sea: the tope shark Galeorhinus galeus, the black-mouthed catshark Galeus melastomus, the starry smooth hound Mustelus asterias, the spiny dogfish Squalus acanthias and the lesser-spotted dogfish Scyliorhinus canicula. Our results were compared to previously described stomach contents and isotopic composition of potential preys. Isotopic ratio delta15N suggested that tope sharks fed at a higher trophic level (16.7 per thousand in the muscle) than the other species, reflecting its piscivorous diet. The lower values of spiny dogfish (11.6 per thousand in the muscle) might be explained, amongst other things, by either its migratory behaviour or its preference for preys from lower trophic levels. Cd and Hg were correlated with isotopic ratios delta13C and delta15N, and were shown to be diet-related whereas Zn, Fe and Cu seemed much more linked to species-specific metabolism. Although this multidisciplinary approach is revealed as a useful tool for the study of shark ecology, the lack of known trophic fractionation suggests that isotopic data be compared to traditional diet analyses.

Marine mammals from northeast Atlantic: relationship between their trophic status as determined by delta13C and delta15N measurements and their trace metal concentrations.

The relationship between trophic position through delta13C and delta15N and trace metal concentrations (Zn, Cd, Cu and Hg) was investigated in the tissues of six marine mammal species from the Northeast Atlantic: striped dolphin Stenella coeruleoalba, common dolphin, Delphinus delphis, Atlantic white-sided dolphin Lagenorhynchus acutus, harbour porpoise Phocoena phocoena, white beaked-dolphin Lagenorhynchus albirostris, grey seal Halichoerus grypus stranded on French Channel and Irish coasts. White-beaked dolphins, harbour porpoises, white-sided dolphins, common and striped dolphins display the same relative and decreasing trophic position, as measured by delta15N values, along both the Irish and French channel coasts, reflecting conservative trophic habits between these two places. Hepatic and renal Cd concentrations were significantly correlated to muscle delta13C and delta15N values while Hg, Zn and Cu did not. These results suggest that Cd accumulation is partly linked to the diet while other factors such as age or body condition might explain Hg, Zn or Cu variability in marine mammals. Combined stable isotope and trace metal analyses appear to be useful tools for the study of marine mammal ecology.

White-sided dolphin metallothioneins: purification, characterisation and potential role.

Metallothioneins (MTs) were characterised in the kidneys of a white-sided dolphin Lagenorhynchus acutus stranded along the Belgian coast, displaying high levels of cadmium (Cd) and mercury (Hg) in liver and kidney. The protein has two isoforms: MT-1 and MT-2. MT-1 binds Cu, Zn, Hg and Cd, while MT-2 only binds Zn, Hg and Cd. This suggests different metabolic functions for the two isoforms: MT-1 is mainly involved in Cu homeostasis; MT-2, which was four-fold more abundant than MT-1, detoxifies most of the accumulated cadmium.

Combined effects of experimental heavy-metal contamination (Cu, Zn, and CH3Hg) and starvation on quail's body condition: parallelism with a wild common guillemot (Uria aalge) population found stranded at the Belgian coast.

Combined effects of heavy-metal contamination (Cu, Zn, and CH3Hg) and starvation were tested on common quails (Coturnix coturnix japonica) and used as a model for comparison with a wild common guillemot (Uria aalge) population found stranded at the Belgian coast. Appropriate heavy-metal levels were given to the quails to obtain concentrations similar to those found in the seabirds's tissues. The contaminated animals were then starved for 4 d to simulate the evident malnutrition symptoms observed at the guillemot's level. In such conditions, food intake and total-body weight are shown to decrease in contaminated individuals with simultaneous significant hepatic and renal increase of the heavy-metal concentrations. Like guillemots, higher heavy-metal levels were observed in those contam- inated quails that had also developed a cachectic status characterized by a general atrophy of their pectoral muscle and complete absence of subcutaneous and/or abdominal fat depots. Although likely the result of a general protein catabolism during starvation, it is suggested that these higher metal levels could as well enhance a general muscle wasting process (cachectic status).

Influence of age, sex and body condition on zinc, copper, cadmium and metallothioneins in common guillemots (Uria aalge) stranded at the Belgian coast.

The common guillemots, Uria aalge, found stranded at the Belgian coast, display high levels of Cu in both liver and kidneys. The condition index of the animals, defined as the ratio of liver to kidneys mass (Wenzel & Adelung, 1996, The suitability of oiled Guillemots (Uria aalge) as monitoring organisms for geographical comparisons of trace element contaminants. Archives of Environmental Contamination and Toxicology, 31, 368-377), influences both the metal concentration and its binding to metallothioneins (MT): the lower the condition index, the more emaciated the animals, and the higher the total Cu concentration and the concentration of Cu bound to MT. In less robust individuals, our results suggest that Cu could displace Zn from MT, rendering the Zn ions available to induce a new MT synthesis. Sex-related effects also emerged as significantly higher hepatic MT as well as Cu- and Zn-MT concentrations were found in emaciated male guillemots compared to females. In both organs, Cd concentrations remained low and typically demonstrated an age-dependent renal accumulation, with no noticeable effect of the condition index. As a whole, these results suggest that, for guillemots found stranded at the Belgian coast. Cu binding to hepatic and renal MT could function as a protective mechanism, rendering the metal ions unavailable to exert any cytotoxic activity.

Heavy metals contamination and body condition of wintering guillemots (Uria aalge) at the Belgian coast from 1993 to 1998.

A sample of 166 common guillemots (Uria aalge) recovered from Belgian beaches during five wintering seasons, from 1993-1994 to 1997-1998, were examined. At necropsy, postmortem examination including body mass, fat reserves, presence or not of intestinal contents, eventual status of oiling, and pathological changes (cachexia, acute hemorrhagic gastroenteropathy (GEAH)) was attributed to each individual. Mild to severe cachexia, a pathology characterized by moderate to severe atrophy of the pectoral muscle as well as reduced amounts or absence of subcutaneous and/or abdominal fat, was observed for most specimens (85.8%). Heavy metal analyses (Cu, Zn, Fe, Cd, Ni, Cr, and Pb) of the tissues (typically liver, kidney, and pectoral muscle) were performed, and total lipids were determined (liver and pectoral muscle). The guillemots collected at the Belgian coast exhibited higher Cu and Zn concentrations compared to individuals collected in more preserved areas of the North Sea such as the northern colonies. A general decrease of their total body mass as well as liver, kidney, and pectoral muscle mass was associated to increasing cachexia severity. Moreover, significantly increasing heavy metal levels (Cu and Zn) in the tissues as well as depleted muscle lipid contents were observed parallel to increasing cachexia severity. On the contrary the organs' total metal burden barely correlates to this status. These observations tend to indicate a general redistribution of heavy metals within the organs as a result of prolonged starvation and protein catabolism (cachectic status). Such a redistribution could well be an additional stress to birds already experiencing stressfull conditions (starvation, oiling).

Metallothioneins in marine mammals.

Metallothioneins (MTs) have been detected in livers and kidneys of 10 marine mammals species (Pinnipeds and Odontocetes). Characterization of renal MTs of striped dolphin has shown that the protein has two isoforms (MT-1 and MT-2) with a molecular weight estimated around 6,800. MT concentrations also vary widely in marine mammals tissues (from 58 to 1,200 microg x g(-1) ww) underlying the numerous parameters involved: physiological status, pregnancy, age, diet. The participation of this protein in metal detoxification has been investigated since high levels of cadmium (Cd) and mercury (Hg) have been measured in livers and kidneys of marine mammals. It has been suggested that those animals can mitigate at least in part, the toxic effects of Cd and Hg through binding to MTs. The percentage of the cytosolic Cd bound to MTs can reach almost 100%. On the contrary, the percentage of hepatic and renal Hg bound to MT is very low (generally less than 10%) and this metal is mainly associated with selenium (HgSe) under a detoxified form in the insoluble fraction of the tissues. MTs appear to play a minor role in the binding and detoxification of Hg by marine mammals. On the contrary, close and dynamic interactions occur between Cd and MTs. Cytosolic MTs appear as a potential short term way of detoxification of Cd accumulated from diet. Long-term detoxification would imply a sequestration of the metal under a precipitated form (e.g. in lysosomes).

A gas chromatographic separation for the h and C stable isotope ratio determination of coal compounds.

A new, completely automated gas chromatography technique has been developed to separate the different gaseous compounds produced during underground coal gasification for their (13)C/(12)C and D/H isotope ratio measurements. The technique was designed for separation and collection of H(2), CO, CO(2), H(2)O, H(2)S, CH(4), and heavier hydrocarbons. These gaseous compounds are perfectly separated by the gas-phase chromatograph and quantitatively sent to seven combustion and collection lines. H(2), CO, CH(4), and heavier hydrocarbons are quantitatively oxidized to CO(2) and/or H(2)O. The isotopic analyses are performed by the sealed-tube method. The zinc method is used for reduction of both water and H(2)S to hydrogen for D/H analysis. Including all preparation steps, the reproducibility of isotope abundance values, for a quantity higher than or equal to 0.1 mL of individual components in a mixture (5 mL of gases being initially injected in the gas chromatograph), is ±0.1‰ for δ(13)C(PDB) and ±6‰ for δD(SMOW).

Role of metallothioneins in metal regulation by the guillemot Uria aalge.

Guillemots, like other seabird species living in the North Sea, appear to be heavily contaminated by copper. Metallothioneins are present in both liver and kidney but, at least in the specimens stranded along the Belgian coast, fail to maintain constant the copper, zinc and cadmium load of the high molecular weight soluble proteins of both organs, stressing the potential toxic role of these metals, mainly copper.

Storage of Hg in the ileum of Blatella germanica: biochemical characterization of metallothionein.

Cockroach ileum has a high capability to concentrate mercury compared with other tissues. Part of the mercury contained in the soluble phase of this organ is bound to metallothionein. It is suggested that mercury of the insoluble phase is stored in lysosomes under a polymerized metallothionein form.

[Nephropathy induced by cadmium in eels adapted to seawater (teleosts)]. / Une néphropathie provoquée par le cadmium chez l'Anguille adaptée à l'eau de mer (Téléostéen).

Nephropathic casts are produced in the kidneys of eels adapted to sea water and submitted to Cd exposure. They are made of phosphate and oxalate of calcium and might contain traces of carbonates. Spherites are formed and grow in the lumen of nephrons and collecting tubules; they are linked to a glycoproteic secretion. They are devoid of Cd and do not contribute to excrete the toxic metal.