Minimal impact at current environmental concentrations of microplastics on energy balance and physiological rates of the giant mussel Choromytilus chorus

Microplastic particles (MP) uptake by marine organisms is a phenomenon of global concern. Nevertheless, there is scarce evidence about the impacts of MP on the energy balance of marine invertebrates. We evaluated the mid-term effect of the microplastic ingestion at the current higher environmental concentrations in the ocean on the energy balance of the giant mussel Choromytilus chorus. We exposed juvenile mussels to three concentrations of microplastics (0, 100, and 1000 particles L⁻¹) and evaluated the effect on physiology after 40 days. The impacts of MP on the ecophysiological traits of the mussels were minimum at all the studied concentrations. At intermediate concentrations of MP, Scope for Growth (SFG) had little impact. Other relevant key life-history and physiological processes, such as size and metabolism, were not affected by microplastics. However, individuals treated with MP presented histopathological differences compared to control group, which could result in adverse health effects for mussels.