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The bioaccumulation of mercury (Hg) in marine organisms through various pathways has not yet been fully explored, particularly in cephalopods. This study utilises radiotracer techniques using the isotope

International audience; Plastic pollution has become a major environmental and societal concern in the last decade. From larger debris to microplastics (MP), this pollution is ubiquitous and particularly affects aquatic ecosystems. MP can be directly or inadvertently ingested by organisms, transferred along the trophic chain, and sometimes translocated into tissues. However, the impacts of such MP exposure on organisms’ biological functions are yet to be fully understood. Here, we used a multi-diagnostic approach at multiple levels of biological organization (from atoms to organisms) to determine how MP affect the biology of a marine fish, the gilthead seabream, Sparus aurata. We exposed juvenile seabreams for 35 days to spherical 10–20 μm polyethylene primary MP through food (Artemia salina pre-exposed to MP) at a concentration of 5 ± 1 μg of MP per gram of fish per day. MP-exposed fish experienced higher mortality, increased abundance of several brain and liver primary metabolites, hepatic and intestinal histological defects, higher assimilation of an essential element (Zn), and lower assimilation of a nonessential element (Ag). In contrast, growth and muscle C/N isotopic profiles were similar between control and MP-exposed fish, while variable patterns were observed for the intestinal microbiome. This comprehensive analysis of biological responses to MP exposure reveals how MP ingestion can cause negligible to profound effects in a fish species and contributes towards a better understanding of the causal mechanisms of its toxicity.

The present study reports the first experimental microplastic-mediated transfer of a key PCB congener into adult specimens of the sea urchin Paracentrotus lividus. Three experiments were conducted to assess whether

Ciguatera poisoning is a food intoxication associated with the consumption of fish or shellfish contaminated, through trophic transfer, with ciguatoxins (CTXs). In this study, we developed an experimental model to assess the trophic transfer of CTXs from herbivorous parrotfish, Chlorurus microrhinos, to carnivorous lionfish, Pterois volitans. During a 6-week period, juvenile lionfish were fed naturally contaminated parrotfish fillets at a daily dose of 0.11 or 0.035 ng CTX3C equiv. g−1, as measured by the radioligand-receptor binding assay (r-RBA) or neuroblastoma cell-based assay (CBA-N2a), respectively. During an additional 6-week depuration period, the remaining fish were fed a CTX-free diet. Using r-RBA, no CTXs were detectable in muscular tissues, whereas CTXs were measured in the livers of two out of nine fish sampled during exposure, and in four out of eight fish sampled during depuration. Timepoint pooled liver samples, as analyzed by CBA-N2a, confirmed the accumulation of CTXs in liver tissues, reaching 0.89 ng CTX3C equiv. g−1 after 41 days of exposure, followed by slow toxin elimination, with 0.37 ng CTX3C equiv. g−1 measured after the 6-week depuration. These preliminary results, which need to be pursued in adult lionfish, strengthen our knowledge on CTX transfer and kinetics along the food web.

The fate and toxicity of ingested marine microplastics (MPs) have been of major concern in aquatic ecotoxicology for the last decade. Although their ingestion by a wide range of marine organisms has been proven, the uptake of MPs within organs is not yet fully understood and relies on the ability of ingested microplastics to transfer from the gut to tissues beyond the digestive wall (i.e., translocation). The present study investigates the in vitro transfer of fluorescent high-density polyethylene particles of different sizes classes (1-5 µm; 10-29 µm; 38-45 µm) across the intestinal wall of the sea urchin Paracentrotus lividus using Ussing chambers. Small microplastics (1-5 µm) were proven to be able to cross the intestinal wall of P. lividus and reach the coelomic fluid, while larger microplastics (≥ 10 µm) were not observed to cross the intestinal wall. Results demonstrate a size-dependent passage of polyethylene microparticles across the intestinal walls of P. lividus for the first time, highlighting the suitability of Ussing chamber systems to study the transfer of MPs across the intestinal wall of animals.

One important aspect of marine plastic pollution is that small particles are ubiquitously present in seawater and can transport a large variety of co-contaminants. The sorption-desorption kinetics of these co-contaminants sorbed to microplastics (MPs) are not fully understood, partially due to the lack of any standardised procedures between studies. The present work aims at describing a new and efficient method to investigate the sorption of co-contaminants onto different types of particles using proven radiotracer techniques. This work provides recommendations as well as a thorough description of the materials, conditions and procedures required to optimise the adsorption of polychlorinated biphenyl (PCB) onto particles. Details of the controlled experimental conditions, such as the volume of the container, the concentration of particles, and specifics of the radiotracer are provided. In addition, a thorough description of the novel filtration methodology specific to these radiotracer techniques is presented, for the first time in the literature. To validate the efficiency of the method, we examined the partition coefficients (Kd) of ¹⁴C-PCB#153 onto virgin MP (10-29 µm polyethylene beads) and onto natural sediment particles that are similarly sized (1-17.8 µm) in seawater. After 40 h, plastic particles adsorbed 25.7% of ¹⁴C-PCB#153 while sediment particles adsorbed 89.3% of the same compound. Results suggest that in this scenario, polyethylene MP particles may be less effective transport vectors of ¹⁴C-PCB#153 than natural sediment particles.•Details of experimental conditions, such as the volume of the container, and the concentration of particles and of radiotracer, were defined•A thorough description of the filtration methodology specific to radiotracer techniques is presented•Results highlight that virgin polyethylene MPs may be less effective transport vectors of ¹⁴C-PCB#153 than natural sediment particles., Graphical abstract Image, graphical abstract

International audience; Plastic pollution has become a major environmental concern worldwide, and marine ecosystems have become polluted with ubiquitous microplastic particles (MP). MP can contain chemical additives and can also scavenge pollutants from the surrounding environment, and these co-contaminants may threaten the marine biota when MP become inadvertently ingested and transferred up the food chain. However, our understanding of the sorption-desorption kinetics of chemical compounds bound to MP remains limited. Moreover, whether MP are better transport vectors of co-contaminants than other natural particles (e.g. sediment) has not received much attention. Here, we used radiotracers to examine the partition coefficients (Kd) of three trace metals (109Cd, 134Cs, and 65Zn) to virgin MP (32–75 μm polyethylene beads) and to natural sediment particles of a similar size (35–91 μm) in seawater. After 72 h, sediment particles adsorbed 2.5% of 109Cd, 68.0% of 134Cs, and 71.0% of 65Zn, while MP adsorbed

The widespread decline in oceanic dissolved oxygen (DO), known as deoxygenation, is a threat to many marine ecosystems, and fish are considered one of the more vulnerable marine organisms. While food intake and growth rates in some fish can be reduced under hypoxic conditions (DO ~ 60 μmol kg−1), the dietary transfer of essential metals remains unclear. In this context, we investigated the influence of DO on the dietary acquisition of two essential metals (Zn and Mn) in the commercially important gilthead seabream (Sparus aurata) using radiotracer techniques. Fish were exposed to variable DO conditions (normoxia 100% DO, mild-hypoxia 60% DO, and hypoxia 30% DO), and fed a single radiolabeled food ration containing known activities of 54Mn and 65Zn. Depuration and assimilation mechanisms under these conditions were followed for 19 d. Based on whole body activity after the radio-feeding, food consumption tended to decrease with decreasing oxygen, which likely caused the significantly reduced growth (- 25%) observed at 30% DO after 19 d. While there was an apparent reduction in food consumption with decreasing DO, there was also significantly higher essential metal assimilation with hypoxic conditions. The proportion of 65Zn remaining was significantly higher (~60%) at both low DO levels after 24 h and 19 d while 54Mn was only significantly higher (27%) at the lowest DO after 19 d, revealing element specific effects. These results suggest that under hypoxic conditions, stressed teleost fish may allocate energy away from growth and towards other strategic processes that involve assimilation of essential metals.

Changes in seawater pH can alter the chemical speciation of waterborne chemical elements, affecting their bioavailability and, consequently, their bioaccumulation in marine organisms. Here, controlled environmental conditions and a 210Pb radiotracer were used to assess the effect of five distinct pH conditions (pHT ranging from 7.16 to 7.94) on the short-term (9 days) accumulation of Pb in the blue mussel, Mytilus edulis. After 9 days of exposure, higher levels of Pb were observed in the soft tissues of mussels maintained in the lower pH conditions, while Pb levels accumulated by mussel shells showed no difference across pH conditions. These results suggest that pH decreases such as those predicted by ocean acidification scenarios could enhance Pb contamination in marine organisms, with potential subsequent contamination and effect risks for human consumers.

Marine plastic debris can act as a reservoir of chemical additives that can pose a potential threat to sensitive ecosystems such as coral reefs. A survey of foam macrodebris collected on beaches indeed revealed high concentrations of hexabromocyclododecanes (ΣHBCDD) in polystyrene (PS) samples (up to 1940 μg g−1). Results also showed that PS fragments can still leach over 150 ng g−1 d−1 of ΣHBCDD (primarily as the α-isomer) for relatively long durations, and that these additives are readily bioaccumulated and well-retained by corals. Despite significant HBCDD bioaccumulation in coral tissue, short-term exposure to HBCDD or PS leachate had no considerable effect on coral photosynthetic activity, symbiont concentration and chlorophyll content. Exposure to the PS leachate did however cause consistent polyp retraction in nubbins over the 5-day exposure. This response was not observed in animals exposed to HBCDD alone, suggesting that another constituent of the leachate stressed corals.

Soulignant la contradiction entre la conception contractualiste de la moralite developpee par J. Narveson et son propre enseignement du liberalisme, l'A. montre qu'une ethique liberale doit reconnaitre l'appartenance des animaux a la communaute morale, des lors que tous les etre sensibles ont une valeur inherente et que leur exploitation par l'homme est limitee a la satisfaction des besoins vitaux

Ingrid Newkirk’s notorious assertion that “a rat is a pig is a dog is a boy” provides the title for Wesley J. Smith’s book decrying the animal-liberation movement and propounding the doctrine of human exceptionalism. More than simply a claim about the superior mental powers of Homo sapiens, human exceptionalism holds that humans possess a unique moral worth that endows them alone, among all living creatures, with the right never to be treated merely as means to the ends of others. The idea that humans have this exceptional moral status is hardly new, but the fact that it has now become an “ism” reflects the current struggle over where to draw the boundaries of the moral community.