Outils d'évaluation de la biodisponibilité des contaminants dans les sols et apport en évaluation des risques pour les écosystèmes.

p71 à 87: texte p85-111: diaporama conférenceNational audienceLa biodisponibilité est la part des contaminants du milieu disponible pour l'assimilation par les organismes. Elle peut être déterminée par mesure des effets (= biodisponibilité toxicologique) et/ou de la bioaccumulation (= biodisponibilité environnementale) des contaminants chez des organismes exposés en laboratoire ou in situ à des sols contaminés. Des exemples d'utilisation des escargots et des plantes pour évaluer la biodisponibilité sont présentés. http://www2.ademe.fr/servlet/KBaseShow?sort=-1&cid=96&m=3&catid=1014

LES ESCARGOTS BIO-INDICATEURS DE LA QUALITE DES SOLS - Snail watch : analyse en laboratoire ou in situ de la biodisponibilité des contaminants

http://www2.ademe.fr/servlet/KBaseShow?sort=-1&cid=96&m=3&catid=10143fiche outil 4 pagesCe document est une fiche outil présentant les possibilités d'utilisation des escargots pou analyse en laboratoire ou in situ de la biodisponibilité des contaminants. Cette fiche a été mise en ligne sur le site de l'ADEME/ sites pollués et sols/ outils méthodologiques: http://www2.ademe.fr/servlet/KBaseShow?sort=-1&cid=96&m=3&catid=1014

Influence de la date d’échantillonnage sur la reproduction de l’escargot terrestre Helix aperta maintenu en conditions contrôlées de température et de photopériode

Reproductive traits of Helix aperta snails were investigated under four combinations of temperature and photoperiod (20°C/16hL:8hD; 20°C/8hL:16hD; 15°C/16hL:8hD and 15°C/ 8hL:16hD). Three samples were used: Sample 1 and Sample 2 collected from Annaba (Northeastern Algeria) during and after hibernation respectively; Sample 3, previously studied (unpublished data), collected from Bejaïa (near Northeastern Algeria) during aestivation. All the snails began to mate on the first week and to lay on the 3rd-4th week of setting under conditions of reproduction. Sample 1 and Sample 2 were characterized by shorter reproduction periods (4-6 weeks) than Sample 3 (5-7 weeks). Strikingly, although most of the snails collected during and after hibernation mated at a high rate (56-87 %) in comparison with those collected during aestivation (32-92 %), their rates of egg-laying were drastically lower (6-25 % against 12-80 %). Among the snails that had mated, only 11-36 % laid eggs in Samples 1 and 2 against 38-87 % in Sample 3. The mean numbers of eggs per clutch were higher in Sample 1 (293-323) and Sample 3 (337-348) than in Sample 2 (237-248) (P < 0.05). Inversely, the mean egg weights per clutch were heavier in Sample 2 (17.5- 17.8 mg) than in Sample 1 (16.1-16.3 mg) and Sample 3 (16.3-16.6 mg) (P < 0.05). After the reproduction period, as a consequence of differential reproductive yields, the mean weights of snails very significantly increased in Sample 1 and Sample 2 (P < 0.001) and significantly decreased in Sample 3 (P < 0.05). Reproductive performances were more affected and lethality rates higher under low temperature and short day photoperiod. The best combination of temperature and photoperiod was mostly 20°C/16hL:8hD, conditions closer to those in the field during autumn, especially overnight, the phase of snail activity. After the reproduction period, the lethality was becoming higher and higher and the surviving snails were less active or trying to burrow themselves into the soil of the egg-laying pots. All these arguments plead that H. aperta snails are better adapted to reproduce in autumn (decreasing days and higher temperatures) after a long aestivation stimulating gametogenesis than in spring (increasing days and lower temperatures) after hibernation inhibiting gametogenesisLes caractères reproductifs des escargots Helix aperta ont été étudiés sous quatre combinaisons de température et photopériode (20°C/16hL 8hD ; 20°C/8hL:16hD ; 15°C/16hL:8hD and 15°C/ 8hL:16hD). Trois échantillons ont été utilisés: Ech. 1 et Ech. 2 collectés à Annaba (Nord-Est Algérien) respectivement durant et après l'hibernation ; Ech. 3, précédemment analysé (données non publiées), collecté à Béjaïa (proche Nord-Est Algérien) durant l'estivation. Tous les escargots ont commencé à s'accoupler dès la 1ère semaine et à pondre durant la 3ème ou la 4ème semaine de leur mise en conditions de reproduction. Ech. 1 et Ech. 2 se sont distingués par leur plus courte période de reproduction (4-6 semaines) en comparaison avec Ech. 3 (5-7 semaines). D'une manière frappante, bien que les escargots collectés durant ou après hibernation (Ech. 1 et Ech. 2) se soient accouplés, dans la plupart des cas, à des taux plus élevés (56-87 %) que ceux échantillonnés durant l'estivation (32-92 %), leurs taux de pontes ont été dramatiquement plus faibles (6-25 % contre 12-80 %). Autrement dit, parmi les escargots qui se sont accouplés dans Ech. 1 et Ech. 2, seulement 11-36 % ont pondu, contre 38-87 % dans Ech. 3. Les nombres moyens d'œufs par ponte étaient plus élevés en Ech. 1 (293-323) et Ech. 3 (337-348) qu'en Ech. 2 (237-248) (P < 0.05). Inversement, les poids moyens des œufs par ponte étaient plus élevés en Ech. 2 (17.5-17.8 mg) qu'en Ech. 1 (16.1-16.3 mg) et Ech. 3 (16.3-16.6 mg) (P<0.05). Après la période de reproduction, en conséquence des rendements reproductifs différentiels, les poids moyens des escargots ont très significativement augmenté en Ech. 1 et Ech. 2 (P < 0.001) et significativement baissé en Ech. 3 (P < 0.05). Les performances reproductives étaient plus affectées et les taux de mortalité plus élevés sous basse température et courte photopériode. La meilleure combinaison de ces deux facteurs était souvent 20°C/16hL:8hD, plus proche des conditions sur le terrain en automne, surtout durant la nuit, phase d'activité des escargots. Après la période de reproduction, la mortalité devenait de plus en plus élevée et les survivants moins actifs ou essayant de s'enfouir dans le sol des pots de ponte. Tous ces arguments plaident que les escargots H. aperta sont mieux adaptés à se reproduire en automne (jours décroissants et températures plus élevées) après une longue estivation stimulant la gamétogenèse qu'au printemps (jours croissants et températures basses) après l'hibernation inhibant la gamétogenèse

Chemical extractions and predicted free ion activities fail to estimate metal transfer from soil to field land snails.

International audienceThis study investigates the relevance of several soil chemical extractions (calcium chloride, acetic acid, citric acid and a four-step sequential procedure) and predicted free metal ion activities in the soil solution to characterise the transfer of trace metals (Cd, Pb, and Zn) from soil to snail soft tissues over a large smelter-impacted area (Metaleurop Nord, Nord-Pas-de-Calais, France). The study was first performed on six snail species together and then specifically on Cepaea sp. and Oxychilus draparnaudi. When the six species were considered together, the accumulation of metals depended mostly on the species. When significant, total or extractable metal concentrations, or the predicted free ion activities, accounted for less than 7% of the variation of the metal concentrations in the snail tissues. Species-specific analyses showed that extractable concentrations explained approximately 25% of the variation of the metal concentrations in O. draparnaudi, and up to 8% in Cepaea snails. When using total soil concentrations and soil properties as explanatory variables, the models were generally slightly better, explaining up to 42% of the variance. The soil extraction procedures and predicted free ion activities used in this study did not accurately estimate the metal transfer from soil to snails and could not be used in risk assessment

Effets de la température et de la photopériode sur la croissance et la reproduction de l’escargot Petit-gris Helix aperta Born (Gastropoda, Pulmonata)

Body growth and reproductive activity of Helix aperta were studied in laboratory conditions over 40 weeks, from hatching to maturity at 15°C and 20°C, and under two photoperiods: 16h-Light /8h-Dark and 8h-Light/16h-Dark. Only temperature, but not photoperiod, had significant effects on body growth; snails reared at 15°C grew slower, took more time to develop and reached a smaller adult body weight than those raised at 20°C. In contrast, the results showed some interaction between photoperiod and temperature on reproduction (length of reproductive activity, numbers of matings and layings) and revealed a predominant effect of photoperiod. Number of eggs per clutch was linked to body weight of snails. The best conditions for growth and reproduction of Helix aperta snails were the combination of a temperature of 20°C and a long-day photoperiod (16h L/8h D)La croissance corporelle et l'activité reproductrice de Helix aperta ont été étudiées en laboratoire de l'éclosion à la maturité, à 15°C et 20°C durant 40 semaines et selon deux photopériodes: 16 h de jour / 8 h de nuit et 8 h de jour / 16 h de nuit. Seule la température, pas la photopériode, a eu des effets significatifs sur la croissance corporelle; les escargots élevés à 15°C se sont développés plus lentement et ont atteint un poids adulte plus petit que ceux élevés à 20°C. En revanche, les résultats ont montré une certaine interaction entre photopériode et température dans la reproduction (durée de l'activité reproductrice, nombre d'accouplements et de pontes) ainsi qu'un effet prédominant de la photopériode. Le nombre d'œufs par ponte est apparu lié au poids des escargots. Les meilleures conditions de croissance et de reproduction de Helix aperta furent la combinaison d'une température de 20°C et d'une photopériode de 16 h de jour / 8 h de nuit

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

Landsnail for Ecotoxicological Assessment of Chemicals and Soil Contamination: – Ecotoxicological Assessment of Chemicals and Contaminated Soils Using the Terrestrial Snail, Helix aspersa, at Various Stage of Its Life Cycle: A Review

International audienc

ISO 15952 - Soil quality - Effects of pollutants on juvenile land snails (Helicidae). Determination of the effects on growth by soil contamination.

International StandardsISO (the International Organization for Standardization) standar

The SET and ERITME indices: Integrative tools for the management of polluted sites.

International audienceTo address the lack of biological methods for assessing soil quality and its contaminant retention capacity and to provide a tool with which stakeholders can assess the risk of transfer of trace elements in the soil to the soil fauna, the Sum of the Excess of Transfers (SET) index from soil to the snail Cantareus aspersus has been broadened to include the internal concentrations of reference (CIRef) for 14 metals and metalloids (As, Cd, Co, Cu, Cr, Hg, Mo, Ni, Pb, Sb, Sn, Sr, Tl and Zn). The coefficient of determination of risk for these elements provides a new assessment tool for stakeholders: the ERITME (Evaluation of the Risk of the Transferred Metal Elements) tool. This upgraded tool has been used to highlight unsuspected risks and revise management priorities at an industrial site. Moreover, using the tool to determine the risk from metal trace elements allows for improved environmental risk assessment, as ERITME is an integrative tool based on the real bioavailability of metals rather than chemical measures that often lead to unsatisfactory assessments of transfer. The SET and ERITME integrative tools, using snails as indicators of trace element zooavailability, can be used in environmental risk assessment