Does trophic level drive organic and metallic contamination in coral reef organisms?

Pauline Fey (1) , Paco Bustamante (2) , P. Bosserelle (3, 4) , B. Espiau (3) , A. Malau (5) , M. Mercader (6) , Emmanuel Wafo (7) , Yves Letourneur (1)

1 ISEA - Institut de sciences exactes et appliquées
2 LIENSs - LIttoral ENvironnement et Sociétés
3 CRIOBE - Centre de recherches insulaires et observatoire de l'environnement
4 SPC - Pacific community
5 Service de l'Environnement - Préfecture des îles Wallis et Futuna
6 CEFREM - Centre de Formation et de Recherche sur les Environnements Méditérranéens
7 MCT - Membranes et cibles thérapeutiques

Metallic and organic pollutants constitute a serious threat for coral reef ecosystems, potentially affecting a great number of species interacting within complex trophodynamic processes. Pesticides, PCBs and trace elements were measured on coral reef communities of three Pacific islands (Moorea, Wallis and New Caledonia) in relation with d15N values, a proxy of trophic level. Several potential sources of organic matter, benthic invertebrates and fish belonging to various trophic strategies were sampled at each island. Wallis and New Caledonia displayed, respectively, the highest concentrations of pesticides and trace elements. In the three islands, most trace element concentrations (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and V) decreased when d15N was rising (i.e. bioreduction), whereas Hg and Se biomagnified with increasing d15N values. Only few trace elements in some islands did not show any significant trend in relation with d15N (i.e., Ag in New Caledonia, Zn in Wallis and As plus Zn in Moorea). PCBs concentrations showed a significant bioreduction in New Caledonia and in Moorea, but a significant biomagnification in Wallis. Aldrin and heptachlor were the only pesticides to show a similar significant bioreduction in the three islands. Other pesticides, such as chlordecone, diazinon, endosulfan I and II, heptachlor-epoxide A and B, lindane and pp’-DDE displayed contrasted patterns (e.g. chlordecone significantly biomagnified in New Caledonia, significantly bioreduced in Wallis and did not displayed any significant trend in Moorea). Finally, for unclear reasons, Moorea displayed only negative significant correlations between d15N and all pesticides (except pp’-DDT). Our results highlight that trophic level, here assessed through d15N values, is a good predictor of metallic trace elements biomagnification or bioreduction in coral reef organisms. However, at large spatial scale, trophic level relevance to predict pesticides and PCBs biomagnification or bioreduction should be considered with caution and studied in close relation with local characteristics.

Mots clés: nitrogen stable isotope; PCBs; pesticides; trace elements; bioreduction; biomagnification; Serranidae; nitrogen stable isotope

Domaines: Ecotoxicologie

Pauline Fey, Paco Bustamante, P. Bosserelle, B. Espiau, A. Malau, et al.. Does trophic level drive organic and metallic contamination in coral reef organisms?. Science of the Total Environment, 2019, 667, pp.208-221. ⟨10.1016/j.scitotenv.2019.02.311⟩. ⟨hal-02343377⟩