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.
Abstract The transfer of Cd, Cu, Ni, Pb, and Zn was evaluated in a soil‐plant (lettuce, Lactuca sativa )–invertebrate (snail, Helix aspersa ) food chain during a microcosm experiment. Two agricultural soils, polluted and unpolluted, were studied. Lettuce was cultivated for eight weeks before introduction of snails into the microcosms (M‐snails). In a parallel experiment, snails were exposed to lettuce only (i.e., without soil) in simpler exposure devices called containers (C‐snails). Snail exposure duration was eight weeks for both M‐ and C‐snails. No effects on snail survival were found. Both M‐ and C‐snails exposed to polluted soil showed a growth reduction, but only after two weeks of exposure. Time‐dependent accumulation in M‐snails exposed to the polluted environment showed a regular increase of Cd and Zn concentrations over time and a rapid increase of Pb concentrations within the first two weeks, which then remained stable. Copper and Ni concentrations did not increase during any of the experiments. Concentrations in M‐ and C‐snails were compared to estimate the relative contribution of soil and plant to the total bioaccumulation. The results suggest that the soil contribution may be higher than 80% for Pb, from 30 to 60% for Zn, and from 2 to 40% for Cd.
Le Parc naturel regional du Morvan a ete le lieu d'activites minieres et metallurgiques des la protohistoire. Il est important de localiser ces dernieres, puis de quantifi er leur impact sur les ecosystemes actuels. C'etait l'objectif du programme « Identifi cation et impact des sites miniers abandonnes sur les ecosystemes aquatiques et terrestres actuels », un projet de recherche mene par l'universite de Bourgogne-Franche-Comte (2009-2013) qui combinait archeologie, geochimie, ecologie et ecotoxicologie. Des cartes de potentiel minier ont d'abord ete dressees afi n de guider l'archeologue dans ses prospections de terrain. La biodisponibilite des elements traces metalliques dans les sols a ete estimee, de meme que leur impact sur la faune et la fl ore. Les eff ets deleteres sur les organismes sont toujours observes, bien que les travaux ayant entraine la contamination remontent souvent a plusieurs centaines, voire milliers d'annees.
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