Spatially Explicit Analysis of Metal Transfer to Biota: Influence of Soil Contamination and Landscape

Concepts and developments for a new field in ecotoxicology, referred to as “landscape ecotoxicology,” were proposed in the 1990s; however, to date, few studies have been developed in this emergent field. In fact, there is a strong interest in developing this area, both for renewing the concepts and tools used in ecotoxicology as well as for responding to practical issues, such as risk assessment. The aim of this study was to investigate the spatial heterogeneity of metal bioaccumulation in animals in order to identify the role of spatially explicit factors, such as landscape as well as total and extractable metal concentrations in soils. Over a smelter-impacted area, we studied the accumulation of trace metals (TMs: Cd, Pb and Zn) in invertebrates (the grove snail Cepaea sp and the glass snail Oxychilus draparnaudi) and vertebrates (the bank vole Myodes glareolus and the greater white-toothed shrew Crocidura russula). Total and CaCl2-extractable concentrations of TMs were measured in soils from woody patches where the animals were captured. TM concentrations in animals exhibited a high spatial heterogeneity. They increased with soil pollution and were better explained by total rather than CaCl2-extractable TM concentrations, except in Cepaea sp. TM levels in animals and their variations along the pollution gradient were modulated by the landscape, and this influence was species and metal specific. Median soil metal concentrations (predicted by universal kriging) were calculated in buffers of increasing size and were related to bioaccumulation. The spatial scale at which TM concentrations in animals and soils showed the strongest correlations varied between metals, species and landscapes. The potential underlying mechanisms of landscape influence (community functioning, behaviour, etc.) are discussed. Present results highlight the need for the further development of landscape ecotoxicology and multi-scale approaches, which would enhance our understanding of pollutant transfer and effects in ecosystems

Utilisation de mollusques gastéropodes pulmonés terrestres (Helix aspersa) et aquatiques (Lymnaea stagnalis et Lymnaea palustris) comme indicateurs de pollution par les éléments métalliques et les xénobiotiques organiques

Nous avons étudié l'accumulation de contaminants et leurs effets sublétaux sur des gastéropodes terrestres et aquatiques. La première partie est consacrée au développement de méthodes de biosurveillance en exposant des escargots (Helix aspersa) d'élevage à des métaux (Cr6+ et Cd2+) et pesticides (diméthoate) en conditions contrôlées. Après 4 semaines, la bioaccumulation des métaux et l'inhibition de croissance sont dose-dépendantes. Le Cd est plus toxique par l'aliment. Le diméthoate, peu accumulé, induit une inhibition dose-dépendante des AChE dès le premier jour. Il inhibe aussi les carboxylestérases, la fécondité et la croissance. Ces inhibitions sont plus fortes depuis le substrat. Un modèle démographique est utilisé pour montrer que la sensibilité d'un THV au contaminant et son élasticité déterminent sa contribution dans les variations de la population. Dans la deuxième partie, on montre que l'inhibition de la croissance de L. stagnalis et L. palustris exposés 4 semaines au Cd au laboratoire est dose-dépendante. La reproduction de L. palustris est réduite. Ces essais sont utilisés pour évaluer la toxicité d'un effluent industriel (Cr, Zn, et Fe) sur la reproduction de L. palustris. L'accumulation du Cr et du Zn est dose-dépendante. Les effets toxiques sur la fécondité ne sont pas corrélés avec les concentrations internes en métaux. Parallèlement, des limnées introduites dans le cours d'eau récepteur de l'effluent ont des concentrations internes qui reflètent la contamination du milieu. En conclusion, ces bioessais permettent de caractériser la toxicité des polluants par leurs effets sublétaux sur des gastéropodes. Chez H. aspersa, la bioaccumulation des métaux et l'inhibition des AChE apparaissent comme des points finaux utilisables en biosurveillance. Les relations établies doivent être validées in situ. Les méthodes élaborées avec les limnées ouvrent des perspectives en évaluation des risques (bioessais) et en biosurveillance (bioindication active).BESANCON-BU Sciences Staps (250562103) / SudocSudocFranceF

Dose‐dependent growth inhibition and bioaccumulation of hexavalent chromium in land snail Helix aspersa aspersa

International audienceAbstract The toxicity of Cr 6+ was determined in a laboratory environment in the snail Helix aspersa aspersa . The effects on growth were evaluated on animals reared in controlled conditions at the age of one month that had been exposed for 28 d to increasing doses of Cr 6+ mixed in with their food. Two experimental groups were set up with concentrations of chromium in the feed of 250 to 1,250 μg/g (test 1) and 100 to 800 μg/g (test 2). Growth inhibition was dose dependent, and the mean EC50 calculated at four weeks for tests 1 and 2 were, respectively, 354.7 and 298.8 μg/g and for the EC10 195.3 and 160.9 μg/g. The levels of Cr 6+ bioaccumulated in the foot and the viscera of the snails were dose dependent in both types of tissues. The highest concentrations occurred in the viscera, the levels being 0.79 μg/g in the controls and reaching 3,067 μg/g in the animals exposed to the maximum contamination (1,250 μg/g). These high levels of bioaccumulation in addition to the lower concentrations of Cr 6+ excreted in the feces than those present in the food suggest that chromium is not physiologically regulated by Helix aspersa. The results provide added support for the use of snails as a model to determine the toxicity of substances in laboratory biotests by measuring the effects on growth and by assessing bioaccumulation

Assessment of whole effluent toxicity on aquatic snails: Bioaccumulation of Cr, Zn, and Fe, and individual effects in bioassays

International audienceWe used a freshwater gastropod, Lymnaea palustris , in chronic bioassays to assess the toxicity of an industrial effluent containing high levels of metals, particularly Cr, Zn, and Fe. Adult snails were exposed for four weeks to different concentrations of effluent sampled at three successive treatment steps (crude effluent, effluent after physicochemical treatment, and after biological treatment). Dose‐dependent responses reflecting exposure (metal bioaccumulation) and effects on survival, fecundity, and malon‐dialdehyde production (a proxy for oxidative stress) were investigated. We found that Cr and Zn were accumulated in snail tissues, whereas Fe was regulated. Body concentrations of Cr and Zn decreased along the effluent‐treatment gradient, particularly after the physicochemical treatment. For controls versus treatments, no effect on malondialdehyde production was detected. Significant effects were noted for fecundity. The number of eggs per individual decreased for snails exposed to 20, 30, and 40% concentrations of physicochemically treated effluent and for snails exposed to an 80% concentration of the biologically treated effluent. A hormetic effect on the number of eggs per individual was observed for snails exposed to 10 and 20% concentrations of the effluent that had been biologically treated. Deleterious effects of the effluent on L. palustris fecundity were not correlated with high internal concentrations of metals in the snails, suggesting that toxicity resulted from other factors

Urbanization, trace metal pollution, and malaria prevalence in the house sparrow.

Anthropogenic pollution poses a threat for the environment and wildlife. Trace metals (TMs) are known to have negative effects on haematological status, oxidative balance, and reproductive success in birds. These pollutants particularly increase in concentration in industrialized, urbanized and intensive agricultural areas. Pollutants can also interfere with the normal functioning of the immune system and, as such, alter the dynamics of host-parasite interactions. Nevertheless, the impact of pollution on infectious diseases has been largely neglected in natural populations of vertebrates. Here, we used a large spatial scale monitoring of 16 house sparrow (Passer domesticus) populations to identify environmental variables likely to explain variation in TMs (lead, cadmium, zinc) concentrations in the feathers. In five of these populations, we also studied the potential link between TMs, prevalence of infection with one species of avian malaria, Plasmodium relictum, and body condition. Our results show that lead concentration is associated with heavily urbanized habitats and that areas with large woodland coverage have higher cadmium and zinc feather concentrations. Our results suggest that lead concentration in the feathers positively correlates with P. relictum prevalence, and that a complex relationship links TM concentrations, infection status, and body condition. This is one of the first studies showing that environmental pollutants are associated with prevalence of an infectious disease in wildlife. The mechanisms underlying this effect are still unknown even though it is tempting to suggest that lead could interfere with the normal functioning of the immune system, as shown in other species. We suggest that more effort should be devoted to elucidate the link between pollution and the dynamics of infectious diseases

Geographical localization of the 16 house sparrow populations sampled in this study.

<p>I - Paris (Jardin des Plantes), II - Cachan, III - Wissous, IV - Cosne-Cours sur Loire, V - Rully, 6 - Paris (Cité internationale universitaire), 7 - Gennevilliers, 8 - Le Mans, 9 - Crégy les Meaux, 10 - Berck, 11 - Thieux, 12 - Seninghem, 13 - Ceffonds, 14 - Crennes, 15 - Réaup-Lisse and 16 - Arles. The five populations in roman numbers were sampled for parasite prevalence and intensity. The zoomed region, in the upper right corner, corresponds to the region Ile de France. Scale bar, 100 km for France and 30 km for the region Ile de France.</p

(a) Negative correlation between Pb concentration in feathers and the axis 1 of the principal component analysis on environmental variables (see materials and methods for more details).

<p>(b) Positive correlation between Cd concentration in feathers and the axis 3 of the principal component analysis. Each point represents a house sparrow population.</p

Pearson’s correlation coefficient matrix among the environmental variables used to characterize 16 house sparrow populations in France. * and ** indicates P values ≤0.05 and ≤0.01, respectively.

<p>Pearson’s correlation coefficient matrix among the environmental variables used to characterize 16 house sparrow populations in France. * and ** indicates P values ≤0.05 and ≤0.01, respectively.</p