Exposure to a microplastic mixture is altering the life traits and is causing deformities in the non-biting midge Chironomus riparius Meigen (1804)

Catégorie : Impacts de la Pollution Plastique
Date :16 juin 2020
Avis TSC : Les études d’impact « sans à priori » se multiplient pour évaluer les effets des microplastiques de différentes origines dans les milieux naturels. Elles consistent à mettre en contact des animaux à différents stades de développement avec des microparticules de plastiques, sans préjuger des toxicité potentielles, juste en s’approchant des quantités observées dans le milieu naturel. Le développement larvaire des insectes est très sensible aux polluants chimiques. Les sauteurs viennent de montrer ici que des microdébris de PET, PS, PVC et PA sont capables d’altérer le cycle larvaire d’une espèce de chironome, même à des concentrations faibles. Ces insectes ressemblant beaucoup à des moustiques, peu de gens s’en offusqueront, mais ce sont de bons indicateurs de la bonne santé d’un écosystème humide.
Stanković, Jelena; Milošević, Djuradj; Savić-Zdraković, Dimitrija; Yalçın, Gülce; Yildiz, Dilvin; Beklioğlu, Meryem; Jovanović, Boris.
Environmental pollution (Barking, Essex : 1987) : 262, 114248.
The effect of microplastics (MP) exposure on the chironomid species Chironomus riparius Meigen, 1804 was investigated using the OECD sediment and water toxicity test. Chironomid larvae were exposed to an environmentally relevant low microplastics concentration (LC), a high microplastics concentration (HC) and a control (C). The LC was 0.007 g m-2 on the water surface + 2 g m-3 in the water column + 8 g m-2 in the sediment, and the HC was 10 X higher than this for each exposure. The size of the majority of the manufactured microplastic pellets varied between 20 and 100 μm. The MP mixture consisted of: polyethylene-terephtalate (PET), polystyrene (PS), polyvinyl-chloride (PVC) and polyamide (PA) in a ratio of 45%: 15%: 20%: 20%, respectively, for the sediment exposure; 100% polyethylene for the water column exposure; and 50% polyethylene: 50% polypropylene for the water surface exposure. Different endpoints were monitored, including morphological changes in the mandibles and mentums of 4th instar larvae, morphological changes in the wings, mortality, emergence ratio, and developmental time. A geometric morphometric analysis showed a tendency toward widening of the wings, elongation of the mentums and changing the shape of the mandibles in specimens exposed to both concentrations of microplastics. The development time of C. riparius was significantly prolonged by the MP treatment: 13.8 ± 0.5; 14.4 ± 0.6; and 15.3 ± 0.4 days (mean ± SD) in the C, LC, and HC, respectively. This study indicates that even environmentally relevant concentrations of MP mixture have a negative influence on C. riparius, especially at the larval stage.