Salinity and dissolved organic carbon both affect copper toxicity in mussel larvae: Copper speciation or competition cannot explain everything

The production of accurate and reliable data on metal toxicity during ecotoxicological bioassays is important for credible environmental risk assessments and management in aquatic environments. Actual measurements and reporting of contaminant concentrations in bioassays are, however, often disregarded; and potential contaminant loss attributable to adsorption processes (e.g., wall adsorption) in bioassays is widely omitted, which can have detrimental effects on calculated metal toxicity thresholds. In the present we assessed copper (Cu) mass balance during a standard 48‐h bioassay test with blue mussel (Mytilus galloprovincialis) embryos to evaluate effects on calculated toxicity endpoints. We demonstrated that measured Cu concentrations at the test conclusion need to be used to quantify the risk of Cu toxicity because nominal Cu and initial Cu concentrations underestimate overall Cu toxicity by up to 1.5‐fold, owing to Cu loss in solution attributable to adsorption and bioaccumulation processes. For the first time we provide evidence that extracellular adsorption to the biological surface of the embryos is the most important sink for total dissolved Cu in a bioassay. We also established that adsorbed extracellular Cu accumulation reduces Cu toxicity to embryos, potentially by inhibiting Cu from entering the cell of the mussel embryo. Environmental factors (e.g., salinity and dissolved organic carbon) did not influence the partitioning of Cu within the laboratory‐based bioassay. The present results 1) demonstrate the importance of differentiating extra‐ and intracellular Cu pools to improve our understanding of Cu toxicity and associated processes, 2) reveal the potential for bias with respect to calculated Cu toxicity thresholds when results are based on nominal and initial Cu concentrations, and 3) point out the need to follow current guidelines for the testing of chemicals to standardize toxicity tests and data reporting. Environ Toxicol Chem 2019;38:561–574. © 2019 SETAC

Section: Discussionmentioning

confidence: 61%

Investigating the fate of copper in a laboratory‐based toxicity test with embryos of Mytilus galloprovincialis: Copper mass balance of a closed bioassay

Zitoun

Hassler²,

Clearwater

et al. 2019

“…Our results imply that 1) the Cu toxicity DOC correction for mussel larvae proposed in previous studies [15,21,39] cannot be extrapolated to the settled life stage, and 2) the first 48 h (up to D-larvae stage) are the most sensitive life stage [40] but only up to AE 2.5 mg DOC/L (Figure 4). At higher DOC concentrations settled mussels are more sensitive and no longer influenced by DOC.…”

mentioning

confidence: 76%

“…Previous experiments indicated that this water was not toxic to mussel larvae [15]. Natural estuarine water (filtered 0.2 mm) was collected in the harbor of Nieuwpoort (Belgium) and used as a source of natural DOC.…”

Section: Mussel Experimentsmentioning

confidence: 99%

“…The results were compared with previously published research on the effect of DOC and salinity on Cu toxicity to mussel larvae [14,15,20,21]. To achieve this goal, settled mussels were exposed to different combinations of salinity, DOC, and Cu.…”

Section: Introductionmentioning

confidence: 99%

“…This indicates that Cu bound to DOC is bioavailable for uptake by settled mussels when chronically exposed. These hypotheses are not contradicted by the fact that DOC reduces both Cu accumulation and toxicity in mussel larvae, which do not feed or possess gills [15,20]. Furthermore, there is evidence that DOC is an important constituent of the diet of (zebra)mussels [34,36].…”

mentioning

confidence: 99%

See 2 more Smart Citations

Salinity, dissolved organic carbon, and interpopulation variability hardly influence the accumulation and effect of copper in Mytilus edulis

Deruytter

Vandegehuchte

Garrevoet

et al. 2017

Self Cite

To improve the ecological relevance of environmental risk assessment, an improved understanding is needed of 1) the influence of environmental conditions on the toxicity of pollutants, and 2) the effect of these factors in combination with possible interpopulation variability. The influences of salinity and dissolved organic carbon (DOC) on the accumulation and effect of copper (Cu) to settled mussels were investigated with mussels from a North Sea and a Baltic Sea population. We found that both populations were equally Cu-sensitive, even though the Baltic Sea population lives in suboptimal conditions. Baltic Sea mussels, however, accumulated more Cu. This suggests that these populations may have different ways of coping with excess Cu. The influence of salinity on Cu toxicity to settled mussels was limited for both populations. An increase in DOC did not decrease the Cu accumulation or effect in either population. This suggests that DOC-Cu complexes are bioavailable for settled mussels. These findings are in contrast with previous research which indicated that DOC decreased the toxicity and accumulation of Cu in the D-larvae life stage. As a consequence, the mussel larval stage is not the most Cu-sensitive life stage at high DOC concentrations. Furthermore, a DOC correction factor for Cu toxicity cannot be used for settled mussels. This should be accounted for in future marine Cu environmental risk assessment. Environ Toxicol Chem 2017;36:2074-2082. © 2017 SETAC.

Mixture toxicity in the marine environment: Model development and evidence for synergism at environmental concentrations

Deruytter

Baert

Nevejan

et al. 2017

Self Cite

Little is known about the effect of metal mixtures on marine organisms, especially after exposure to environmentally realistic concentrations. This information is, however, required to evaluate the need to include mixtures in future environmental risk assessment procedures. We assessed the effect of copper (Cu)-Nickel (Ni) binary mixtures on Mytilus edulis larval development using a full factorial design that included environmentally relevant metal concentrations and ratios. The reproducibility of the results was assessed by repeating this experiment 5 times. The observed mixture effects were compared with the effects predicted with the concentration addition model. Deviations from the concentration addition model were estimated using a Markov chain Monte-Carlo algorithm. This enabled the accurate estimation of the deviations and their uncertainty. The results demonstrated reproducibly that the type of interaction-synergism or antagonism-mainly depended on the Ni concentration. Antagonism was observed at high Ni concentrations, whereas synergism occurred at Ni concentrations as low as 4.9 μg Ni/L. This low (and realistic) Ni concentration was 1% of the median effective concentration (EC50) of Ni or 57% of the Ni predicted-no-effect concentration (PNEC) in the European Union environmental risk assessment. It is concluded that results from mixture studies should not be extrapolated to concentrations or ratios other than those investigated and that significant mixture interactions can occur at environmentally realistic concentrations. This should be accounted for in (marine) environmental risk assessment of metals. Environ Toxicol Chem 2017;36:3471-3479. © 2017 SETAC.