Impact of ocean acidification on the availability and uptake of trace elements by mussels

Abstract

Global environmental changes have been reported over the last years and their impact on organisms’ behaviour has been studied. Recent studies already demonstrated that in marine systems the release of contaminants in association with predicted environmental changes (increase in CO2 and decrease in pH) may play a key role not only in the organisms’ behavior but also on contaminants toxicity. Therefore, the aim of the present study is to assess the impact of oceanic acidification on the bioavailability of wellstudy metals (Cd, Cu, Pb, Ag) and emerging contaminants (Ce and Pt) and to understand if this environmental change will increase the adverse effects in aquatic environments, using mussels (M. galloprovincialis) as bioindicators. Metal treatments were done by a mixture of isotopically-labelled metals at realistic concentrations: 111Cd (80 ng/L), 65Cu (2 μg/L), 207Pb (200 ng/L), 109Ag (20 ng/L), 142Ce (20 ng/L) and 194Pt (2 ng/L). Two different seawater CO2 concentrations were selected: 400 ppm (current value) and 1200 ppm (estimated content for 2100) (IPCC, 2014). Mussels were exposed for 21 days at spikedseawater constant flow (9 ml/min), under control conditions (16ºC, 12:12 photoperiod) and with constant food addition (1:1, Rhodomonas:T-Iso) (1 mg/L). During the exposure period samples of seawater and phytoplankton were taken to determine metal content and isotopic composition. During the experimental period biological responses were measured by analyzing weekly filtration rates (PAMAS laser particle counter), and at the end of this period by measuring byssus strength. Biochemical responses were assessed by measuring mussel metabolic capacity, energy-related biomarkers, oxidative stress and neurotoxic status. Chemical analyses were done in mussel byssus, gills, feet, glands and soft bodies as well as in water samples. Expected results will help us to understand the influence of seawater acidification on the impacts of pollutants and sensitivity of mussels towards these pollutants, identifying possible synergistic effects