Abstract
Intertidal species are frequently exposed to environmental changes associated with multiple stressors, which they must either avoid or tolerate by developing physiological and biochemical strategies. Some of the natural environmental changes are related with the tidal cycle which forces organisms to tolerate the differences between an aquatic and an aerial environment. Furthermore, in these environments, organisms are also subjected to pollutants from anthropogenic sources. The present study evaluated the impacts in Mytilus galloprovincialis exposed to multi-walled carbon nanotubes (0.01 mg/L MWCNTs) when continuously submersed or exposed to tides (5 h of low tide, 7 h of high tide) for 14 days. Our results demonstrated that mussels were physiologically and biochemically affected by MWCNTs, especially when exposed to tides. In fact, when only exposed to the carbon nanoparticles or only exposed to tides, the stress induced was not enough to activate mussels’ antioxidant defenses which resulted in oxidative damage. However, when mussels were exposed to the combination of tides and MWCNTs increased metabolism was observed, associated with a possible higher production of reactive oxygen species (ROS), leading to a significant increase in the activities of antioxidant enzymes (superoxide dismutase, SOD and glutathione peroxide, GPx) and oxidized glutathione content (GSSG), preventing the occurrence of cellular damage, expressed as no lipid peroxidation (LPO) or protein carbonylation (PC). Therefore, organisms seemed to be able to tolerate MWCNTs and air exposure during tidal regime; however, the combination of both stressors induced higher oxidative stress. These findings indicate that the increasing presence of carbon nanoparticles in marine ecosystems can induce higher toxic impacts in intertidal organisms compared to organisms continuously submerged. Also, our results may indicate that air exposure can act as a cofounding factor on the assessment of different stressors in organisms living in coastal systems.
Highlights
IntroductionT biogeochemical cycling of metals and nutrients, as well as habitat and food source for wildlife IP (Caçador et al, 2007; Mitsch and Gosselink, 2015; Xiao and Li, 2004)
Estuaries are ecologically and economically valuable ecosystems, presenting several essential ecological functions such as high biological productivity, hydrological regulation,T biogeochemical cycling of metals and nutrients, as well as habitat and food source for wildlife IP (Caçador et al, 2007; Mitsch and Gosselink, 2015; Xiao and Li, 2004)
multi-walled CNTs (MWCNTs) characterization The mean size and the polydispersity index (PDI) of simulated seawater samples collected from aquaria containing mussels (Mytilus galloprovincialis) were measured by dynamic light scattering (DLS)
Summary
T biogeochemical cycling of metals and nutrients, as well as habitat and food source for wildlife IP (Caçador et al, 2007; Mitsch and Gosselink, 2015; Xiao and Li, 2004) These ecological R functions are strongly influenced by physical and chemical disturbances from natural or C anthropogenic sources, typical of transitional coastal ecosystems (Dauvin and Ruellet, 2009; S Elliott and Quintino, 2007). Due to their nature, coastal systems, namely estuaries and coastal U lagoons, represent one of the hardest environments to endure for the inhabiting organisms. For example, an increase on antioxidant defenses in the mussels Perna perna and Mytilus galloprovincialis as a defense mechanism
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