Assessing relative sensitivity of marine and freshwater bivalves following exposure to copper: Application of classical and novel genotoxicological biomarkers

Abstract

Determination of relative sensitivity of biota following exposures to contaminants including metals is important for environmental protection. Copper (Cu), although biologically essential can be highly toxic to biota if present at higher concentrations in the natural environment. Given its ubiquitous presence within coastal and inland water bodies, we compared Cu-induced genotoxicity in two ecologically important mussel species, the freshwater Dreissena polymorpha (DP) and marine Mytilus galloprovincialis (MG), along with its tissue specific accumulation. Novel biomarker in terms of induction of gamma H2AX (γ-H2AX) foci, along with comet assay and induction of micronuclei (MN) were used to determine DNA damage response (DDR) in these two species following exposure to a range of Cu concentrations (18, 32, 56 µg L-1) for 10 days. Concentration-dependent increases in Cu concentration in gill tissue, as determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), were paralleled by a greater degree of genotoxicity. An induction of γ-H2AX foci was present in all Cu exposure concentrations, proving this technique to be a sensitive and suitable biomarker of genotoxicity in bivalves. The multibiomarker approach adopted here suggests firstly that in parallel with MG, which is widely used to assess the health of marine and coastal environment, DP is also suitable representative of inland water bodies, and that there is a similar mechanism of action for the induction of genotoxicity between the two species, following exposure to Cu. Secondly, for genotoxicity assessment a battery of responses could simultaneously be assessed in these two bivalve species. Finally, for adequate protection of the environment it is vital to adopt a multi-biomarker, multi-species approach to determine adverse biological effects to gain a holistic understanding of the real threat posed by contaminants to hydrosphere.

Evaluation of interactive effects of phosphorus-32 and copper on marine and freshwater bivalve mollusks

“…Cu concentrations (18 μg L-1) were reflective of environmental realistic values, and in line with previous studies (Al-Subiai et al 2011;Vernon and Jha 2019).…”

“…Exposure of the mussels to 32P alone caused no significant increase in % Tail DNA (Excluding DP [0.1] and MG digestive gland [1 mGy d-1]), but when combined with Cu, % Tail DNA was statistically greater than controls in MG gill and DP digestive gland at 0.10 mGy d-1, and all species and tissues at 1 mGy d-1. Cu in isolation, at environmentally relevant concentrations (18 µg L-1) has been found to have no significant effect on % Tail DNA in MG or DP gill cells (Vernon and Jha 2019), when in combination with 32P there appears to be an additive effect on mussels. Whilst not significantly so the addition of Cu to IR exposures also increased γ-H2AX foci induction, across both species, tissue and dose rate (excluding MG digestive gland).…”

“…Typically, permitted Cu levels in England and Wales are 5 μg L-1 in seawater and between 1-28 μg L-1 in freshwater (dependant on water hardness, DEFRA 2014), however total dissolved Cu in contaminated environments, such as around NPPs can reach concentrations of 689 μg L-1 (Bryan and Gibbs 1983). Cu-induced damaging effects in aquatic invertebrates are well studied (Al-Subiai et al 2011;Vosloo et al 2012;Brooks et al 2015;Xu et al 2016;Vernon and Jha, 2019), and much research has focused on interactions between Cu and additional stressors such as metals, ocean acidification, temperature, pesticides, microplastics (Clayton et al 2000;Bouskill et al 2006;Trevisan et al 2011;Maria et al 2013;Lewis et al 2016). However, to our knowledge no studies have determined the potential interactive effects of IR and Cu in mussels.…”

“…In this study the effects of 32P and Cu, alone and in combination were studied in two ecologically relevant adult bivalve species. Mytilus galloprovincialis (MG) and Dreissena polymorpha (DP) were selected as representatives of marine and freshwater environments (McDonald et al 1991;Binelli et al 2015;Vernon et al 2018;Vernon and Jha, 2019). Mussels are well established model species in ecotoxicological studies and as such the physiology, anatomy and ecology of MG and DP are well understood.…”

Effects of pollution on marine organisms

“…Vernon and Jha (2019) exposed salt and freshwater mussels ( M. galloprovincialis and Dreissena polymorpha ) to Cu for 10 days. Concentrations of 25.2 to 51.6 μg/L (actual) significantly induced DNA strand breaks (measured by comet assay) and micronuclei in gills of both species, with little interspecies difference.…”