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Organophosphate flame retardants (OPFRs) are (re-)emergent environmental pollutants increasingly being used because of the restriction of other flame retardants. The chlorinated OPFR, tris(1,3-dichloro-2-propyl) phosphate (TDCPP) is among those of highest environmental concern, but its potential effects in the marine environment have rarely been investigated. We exposed a widely used sentinel marine mussel species, Mytilus galloprovincialis, to 10 μg L -1 of TDCPP during 28 days and studied: (i) the kinetics of bioaccumulation and elimination of the compound, (ii) the effect on two molecular biomarkers, glutathione S-transferase (GST) and acetylcholinesterase (AChE) activities, and (iii) proteomic alterations in the gills, following an isobaric labeling quantitative shotgun proteomic approach, at two exposure times (7 and 28 days). Uptake and elimination of TDCPP by mussels were very fast, and the bioconcentration factor of this compound in mussels was 147 L kg ww -1 , confirming that this compound is not very bioaccumulative, as predicted by its chemical properties. GST activity was not affected by TDCPP exposure, but AChE activity was inhibited by TDCPP at both 7 and 28 days of exposure. Proteomic analysis revealed subtle effects of TDCPP in mussel gills, since few proteins (less than 2 % of the analysed proteome) were significantly affected by TDCPP, and effect sizes were low. The most relevant effects detected were the up-regulation of epimerase family protein SDR39U1, an enzyme that could be involved in detoxification processes, at both exposure times, and the down-regulation of receptor-type tyrosine-protein phosphatase N2-like (PTPRN2) after 7 days of exposure, which is involved in neurotransmitter secretion and might be related to the neurotoxicity described for this compound. Exposure time rather than TDCPP exposure was the most important driver of protein abundance changes, with 33 % of the proteome being affected by this factor, suggesting that stress caused by laboratory conditions could be an important confounding factor that needs to be controlled in similar ecotoxicology studies. Proteomic data are available via ProteomeXchange with identifier PXD019720., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Global production of synthetic polymers, led by polyethylene (PE), rose steadily in the last decades, and marine ecosystems are considered as a global sink. Although PE is not biodegradable, in coastal areas it fragments into microplastics (MP) readily taken up by biota, and have been postulated as vectors of hydrophobic chemicals to marine organisms. We have tested this hypothesis using two organisms representative of the marine plankton, the holoplanktonic copepod Acartia clausi , and the meroplanktonic larva of the Paracentrotus lividus sea-urchin, and two model chemicals with similar hydrophobic properties, the 4-n-Nonylphenol and the 4-Methylbenzylidene-camphor used as plastic additive and UV filter in cosmetics. Both test species actively ingested the MP particles. However, the presence of MP never increased the bioaccumulation of neither model chemicals, nor their toxicity to the exposed organisms. Bioaccumulation was a linear function of waterborne chemical disregarding the level of MP. Toxicity, assessed by the threshold (EC 10) and median (EC 50) effect levels, was either independent of the level of MP or even in some instances significantly decreased in the presence of MPs. These consistent results challenge the assumption that MP act as vectors of hydrophobic chemicals to planktonic marine organisms. Unlabelled Image • Sea-urchin pluteus and copepod nauplius larvae actively ingest microplastic particles. • Microplastics did not increase accumulation of organic chemicals in sea-urchin larvae. • Microplastics did not increase the toxicity or 4-n-NP or 4-MBC to zooplankton. • PE microplastics do not act as vectors of hydrophobic organics to zooplankton. [ABSTRACT FROM AUTHOR]

This study assessed the environmental risk on coastal ecosystems posed by three phenolic compounds of special environmental and human health concern used in plastics and household products: bisphenol A (BPA), triclosan (TCS) and 4-nonylphenol (4-NP). These three chemicals are among the organic contaminants most frequently detected in wastewater. The most toxic compound tested was 4-NP, with 10% effective concentration at 11.1 μg L −1 for Isochrysis galbana , 110.5 μg L −1 for Mytilus galloprovincialis , 53.8 μg L −1 for Paracentrotus lividus , and 29.0 μg L −1 for Acartia clausi , followed by TCS (14.6 μg L −1 for I. galbana , 149.8 μg L −1 for M. galloprovincialis , 129.9 μg L −1 for P. lividus , and 64.8 μg L −1 for A. clausi ). For all species tested, BPA was the less toxic chemical, with toxicity thresholds ranging between 400 and 1200 μg L −1 except for A. clausi nauplii (186 μg L −1 ). The relatively narrow range of variation in toxicity considering the broad physiological differences among the biological models used point at non-selective mechanisms of toxicity for these aromatic organics. Microalgae, the main primary producers in pelagic ecosystems, showed particularly high susceptibility to the chemicals tested. When the toxicity thresholds experimentally obtained were compared to the maximum environmental concentrations reported in coastal waters, the risk quotients obtained correspond to very low or low risk for BPA and TCS, and from low to high for 4-NP. [ABSTRACT FROM AUTHOR]

The edible clam Dosinia exoleta has been reported to accumulate high contents of lead (Pb) in soft tissues disregarding the levels of Pb in the environment. This is due to the retention of Pb in the form of metal rich granules (MRG) in their kidneys throughout the mollusc lifespan. The potential for trophic transfer of Pb in this form to predators is expected to be low, since metals in the form of MRG are generally supposed to be trophically unavailable, but this assumption is based on studies with other metals (Ag, Cd, Cu or Zn) and has not been demonstrated with Pb until now. This study was designed to test if the Pb present in D. exoleta in the form of MRG is available to a decapod consumer, the common prawn Palaemon serratus, in comparison with a mussel diet showing a different subcellular distribution of Pb. As hypothesised, despite the high Pb concentrations (15 µg g −1 ww) offered to the prawns as D. exoleta tissues, Pb was almost completely unavailable for trophic transfer, and the prawns fed with this diet during 28 days showed the same Pb accumulation as prawns fed with a control diet with a much lower Pb concentration. On the contrary, individuals fed with mussel tissues containing the same Pb concentrations as the diet based on D. exoleta tissues showed 10 times higher Pb bioaccumulation, corresponding to a trophic transfer factor of 1.1%. Subcellular fractionation experiments revealed that the fraction of Pb in the form of MRG was much lower for the mussel, confirming, as observed for other metals, that MRG-associated Pb is not available for trophic transfer to decapod crustaceans. [ABSTRACT FROM AUTHOR]

In this study, PCB-153 bioaccumulation kinetics and concentration-response experiments were performed employing wild Mytilus galloprovincialis mussels. In addition, the activity of three enzymatic biomarkers: glutathione S-transferase (GST), glutathione peroxidase (GPx) and acetylcholinesterase (AChE), were measured in the mussel gills. The experimental data fitted well to an asymptotic accumulation model with a high bioconcentration factor (BCF) of 9324 L kg −1 and a very limited depuration capacity, described by a low excretion rate coefficient ( K d = 0.083 d −1 ). This study reports by first time in mussels significant inhibition of GST activity and significant induction of GPx activity as a result of exposure to dissolved PCB-153. In contrast, AChE activity was unaffected at all concentrations and exposure times tested. The effects on both enzymes are time-dependent, which stresses the difficulties inherent to the use of these biomarkers in chemical pollution monitoring programs. [ABSTRACT FROM AUTHOR]

Wild marine mussels, Mytilus galloprovincialis showed a moderate bioaccumulation ability when exposed to waterborne 4-nonylphenol (4-NP), with a bioconcentration factor (BCF) of 6850 L Kg −1 (dry weight). Kinetic and concentration-response experiments were performed and three enzymatic biomarkers in mussel gills were measured: Glutathione S-transferase (GST), glutathione peroxidase (GPx) and acetylcholinesterase (AChE). Exposure of mussels to environmentally relevant concentrations (25–100 μg L −1 ) of 4-nonylphenol significantly inhibited the AChE activity and induced the GST and GPx activities. GST induction was dose dependent whilst GPx activity showed a less consistent pattern, but in both cases the induction remained after a 10 d depuration period. Mussels seem capable of eliminating 4-NP from their tissues through a mechanism involving GST induction. [ABSTRACT FROM AUTHOR]

In the present work, we study the effects that aggregation of humic acids in seawater, and its adsorption to surfaces, can have on the determination of Cu and Pb accumulation by phytoplankton within the context of metal bioavailability studies, using the diatom Thalassiosira weissflogii. Two methods commonly used for collection of algae to analyse metal content, filtration and centrifugation, were compared, and a procedure to differentiate the metal internalized by the alga from that adsorbed to cell walls-washing with 0.01 M ethylenediaminetetraacetic acid (EDTA)- was optimized for its use in seawater and in the presence of humic acids. The present results highlight the possibility of obtaining biased results if filtration is used to isolate the algae, and show that centrifugation is a more suitable procedure minimizing contribution of particulate and colloidal forms of metals to the measured cellular and intracellular metal contents. Thus a combination of centrifugation to isolate the algae from the medium with a 10 minutes washing with a washing agent composed of EDTA 0.01 M at pH 8 and NaCl and KCl to 0.5 M ionic strength is recommended to extract metals adsorbed to the surfaces of marine phytoplankton for a seawater containing humic substances. The importance of discriminating between internalized metal and total cellular metal in bioavailability studies is noted, given the different effects of humic substances on metal accumulation in the different cellular pools. [ABSTRACT FROM AUTHOR]

Copper uptake and accumulation by the marine mussel Mytilus edulis were studied at different Cu concentrations in chemically defined artificial seawater in the presence and absence of fulvic acids. Both short-term uptake of Cu by excised mussel gills and Cu accumulation in whole mussels after 24 h of exposure decreased in the presence of fulvic acids compared with their absence at similar dissolved Cu concentrations. Calculations of Cu speciation based on previous measurements of labile Cu by anodic stripping voltammetry demonstrated that Cu uptake and accumulation depended on the concentration of labile Cu, in agreement with the free ion activity model. No evidence of a significant uptake of Cu-fulvic acid complexes was observed. Environ. Toxicol. Chem. 2012; 31: 1807-1813. © 2012 SETAC [ABSTRACT FROM AUTHOR]

The use of marine bivalves in metal pollution monitoring is undoubtedly one of the best tools to evaluate metal pollution in coastal areas worldwide. However, since bivalves integrate metal pollution from both the dissolved and the particulate phases, it cannot be assured that metal bioaccumulation in their tissues will predict the risk posed by metals to sensitive organisms such as invertebrate larvae or microalgae, which are known to be mainly affected by the free metal ion fraction. This study aims to test the usefulness of mussel gills-the primary exchange surfaces with dissolved metals-in reflecting dissolved metal bioavailability in the field. For that, we analyzed metal concentrations in environmental samples (whole soft tissues of mussels, mussel gills, sediment, and particulate and dissolved fractions in the water column) collected from 7 sampling sites during a multi-year investigative monitoring survey in the Ría de Vigo. The results showed a different pattern of Cu and Zn accumulation in gills compared to whole soft tissues, and these differences are attributable to the faster response of gills to changes in dissolved metal concentrations and to the regulation of essential metals at the whole body level. In the case of Pb, by contrast, concentrations in gills were very similar to those in the whole body. The use of mussel gills in metal pollution biomonitoring is a promising tool for the detection of changes in bioavailable metals in the environment, especially for essential metals such as Cu and Zn. [ABSTRACT FROM AUTHOR]

In this study the bioaccumulation kinetics of organic UV filters, such as 4-MBC, BP-3, BP-4, OC and OD-PABA in wild Mytilus galloprovincialis mussels was investigated. The uptake and accumulation of waterborne 4-MBC, BP-4 and OC was very rapid, and after only 24 h of exposure to 1 μg L −1 , the tissular concentrations were 418, 263 and 327 μg kg −1 d.w., respectively. The kinetics of bioaccumulation of BP-4 and OC significantly fitted to an asymptotic model with BCF values of 905 L kg −1 and 2210 L kg −1 , respectively. Measured bioaccumulation of the hydrophilic chemical BP-4 was much higher than predicted by K ow -based bioconcentration models, which would lead to a marked underestimation of actual risk. On the other hand, the patterns of uptake found for BP-3 and OD-PABA suggest biotransformation ability of mussels for these two chemicals. [ABSTRACT FROM AUTHOR]

The role of the biopolymer polyhydroxybutyrate (PHB, <250 µm) as a vehicle of a synthetic musks mixture (celestolide, galaxolide, tonalide, musk xylene, musk moskene and musk ketone) to Mytilus galloprovincialis was investigated. For 30 days, virgin PHB, virgin PHB+musks (6.82 µg g-1) and weathered PHB+musks, were daily spiked into tanks containing mussels, followed by a 10-day depuration period. Water and tissues samples were collected to measure exposure concentrations and accumulation in tissues. Mussels were able to actively filter microplastics in suspension but the concentration of the musks found in tissues (celestolide, galaxolide, tonalide) were markedly lower than the spiked concentration. Estimated Trophic Transfer Factors suggest that PHB will only play a minor role on musks accumulation in marine mussels, even if our results suggest a slightly extended persistence in tissues of musks loaded to weathered PHB. • PHB micro particles are not responsible for significant musks accumulation in mussel tissues. • Trophic Transfer Factors should be employed to understand the role of MPs as vectors of HOCs accumulation in tissues. • The use of weathered MPs is recommended to achieve a greater ecological significance. [ABSTRACT FROM AUTHOR]

Copper (Cu) complexation by humic acids (HA) is expected to decrease Cu bioavailability for aquatic organisms as predicted by metal bioavailability models, such as the biotic ligand model (BLM). This has been confirmed for non-feeding organisms such as marine invertebrate embryos or microalgae, but for filter-feeding organisms such as the mussel Mytilus edulis , Cu bioaccumulation was higher in the presence of HA, suggesting that part of the Cu-HA complexes were available for uptake. This study shows the dynamic modeling of Cu accumulation kinetics in the gills and rest of the soft-body of M. edulis in the absence and presence of HA. Assuming that truly dissolved Cu is taken in the body via the gills following BLM premises, and including uptake of Cu-HA aggregates via the gut into the rest compartment, this two-compartmental model could successfully explain the observed bioaccumulation data. This modeling approach gives strong evidence to the hypothesis that Cu-HA aggregates can be ingested by mussels leading to Cu absorption in the digestive system. [ABSTRACT FROM AUTHOR]