Mercury in Juvenile Solea senegalensis: Linking Bioaccumulation, Seafood Safety, and Neuro-Oxidative Responses under Climate Change-Related Stressors

Carolina Camacho,António Marques,Vera Barbosa,Rui Rosa,M Leonor Nunes,Ana Luísa Maulvault,Fabíola H S Fogaça,Pedro Pousão-Ferreira,Marta T Santos

doi:10.3390/app10061993

Abstract

Mercury (Hg) is globally recognized as a persistent chemical contaminant that accumulates in marine biota, thus constituting an ecological hazard, as well as a health risk to seafood consumers. Climate change-related stressors may influence the bioaccumulation, detoxification, and toxicity of chemical contaminants, such as Hg. Yet, the potential interactions between environmental stressors and contaminants, as well as their impacts on marine organisms and seafood safety, are still unclear. Hence, the aim of this work was to assess the bioaccumulation of Hg and neuro-oxidative responses on the commercial flat fish species Solea senegalensis (muscle, liver, and brain) co-exposed to dietary Hg in its most toxic form (i.e., MeHg), seawater warming (ΔT°C = +4 °C), and acidification (pCO2 = +1000 µatm, equivalent to ΔpH = −0.4 units). In general, fish liver exhibited the highest Hg concentration, followed by brain and muscle. Warming enhanced Hg bioaccumulation, whereas acidification decreased this element’s levels. Neuro-oxidative responses to stressors were affected by both climate change-related stressors and Hg dietary exposure. Hazard quotient (HQ) estimations evidenced that human exposure to Hg through the consumption of fish species may be aggravated in tomorrow’s ocean, thus raising concerns from the seafood safety perspective.

Highlights

Mercury (Hg) is a metal of great concern to seafood consumers and health authorities, as it accumulates in some seafood species (e.g., References [1,2,3]) and has a high degree of environmental persistence and toxicity [4]
Change change-related stressors influence Hg bioaccumulation and elimination in juvenile Solea senegalensis in Theways, present study revealed that warming, the co-occurrence of bothwas climate different depending on tissue affinity to thisacidification, element
Despite the significantly higher Hg concentrations found in the liver, the present findings show that neuro-oxidative responses triggered by Hg were more notorious in the brain (i.e., significant differences were found between non-contaminated and Hg contaminated fish in lipid peroxidation (LPO), CAT, Superoxide dismutase (SOD), and AchE activities, and negative correlations between these variables and Hg net accumulation rates (NAR) occurred in this tissue, a result that is consistent with the mode of action of this contaminant (e.g., Reference [84])

Summary

Introduction

Mercury (Hg) is a metal of great concern to seafood consumers and health authorities, as it accumulates in some seafood species (e.g., References [1,2,3]) and has a high degree of environmental persistence and toxicity [4]. From an ecological perspective, increased levels of MeHg contamination were previously associated with diminished animal resilience [17,18], reproductive success [19], and biodiversity [20]. In line with these impacts, previous studies on marine species exposed to

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