International audience | The common mussel Mytilus galloprovincialis was selected as unique biomonitor species to implement a regional monitoring programme, the CIESM Mediterranean Mussel Watch (MMW), in the Mediterranean and Black Seas. As of today, and upon standardization of the methodological approach, the MMW Network has been able to quantify 137Cs levels in mussels from 60 coastal stations and to produce the first distribution map of this artificial radionuclide at the scale of the entire Mediterranean and Black Seas. While measured 137Cs levels were found to be very low (usually <1 Bq kg-1 wet wt) 137Cs activity concentrations in the Black Sea and North Aegean Sea were up to two orders of magnitude higher than those in the western Mediterranean Basin. Such effects, far from representing a threat to human populations or the environment, reflect a persistent signature of the Chernobyl fallout in this area. © 2007 Elsevier Ltd. All rights reserved.

Reproduction and planktonic phase of life of edible shellfishes, Mytilus galloprovincialis Lamk. and Ostrea edulis L. were the subject of the investigations. Biological and ecological characteristics of mentioned species have been studied in Boka Kotorska Bay (Adriatic Sea), Montenegro (Yugoslavia), having in mind data from the Adriatic Sea and Mediterranean. Beside, some localities from Boka Kotorska Bay, conveniet for their rearing, were described , too. A period of their appearance in plankton was considered before all.

Amyl salicylate (AS) is a fragrance massively used as a personal care product and following the discharged in wastewaters may end up in the aquatic environment representing a potential threat for the ecosystem and living organisms. AS was recently detected in water of the Venice Lagoon, a vulnerable area continuously subjected to the income of anthropogenic chemicals. The lagoon is a relevant area for mollusc farming, including the Mediterranean mussels (Mytilus galloprovincialis) having an important economic and ecological role. Despite high levels of AS occurred in water of the Lagoon of Venice, no studies investigated the possible consequences of AS exposures on species inhabiting this ecosystem to date. For the first time, we applied a multidisciplinary approach to investigate the potential effects of the fragrance AS on Mediterranean mussels. To reach such a goal, bioaccumulation, cellular, biochemical, and molecular analyses (RNA-seq and microbiota characterization) were measured in mussels treated for 7 and 14 days with different AS Venice lagoon environmental levels (0.1 and 0.5 μg L⁻¹). Despite chemical investigations suggested low AS bioaccumulation capability, cellular and molecular analyses highlighted the disruption of several key cellular processes after the prolonged exposures to the high AS concentration. Among them, potential immunotoxicity and changes in transcriptional regulation of pathways involved in energy metabolism, stress response, apoptosis and cell death regulations have been observed. Conversely, exposure to the low AS concentration demonstrated weak transcriptional changes and transient increased representation of opportunistic pathogens, as Arcobacter genus and Vibrio aestuarianus. Summarizing, this study provides the first overview on the effects of AS on one of the most widely farmed mollusk species.

Microplastic pollution is emerging as a global environmental issue, and its potential for transferring hazardous chemicals to aquatic organisms is gaining attention. Studies have investigated the transfer of chemicals, mainly sorbed chemicals, through ingestion of microplastics by organisms, but limited information is available regarding chemical additives and uptake via the aqueous route through plastic leaching. In this study, we compared two bioaccumulation pathways of the additive hexabromocyclododecane (HBCD) by exposing mussels (Mytilus galloprovincialis) to two different sizes of expanded polystyrene (EPS): inedible size (4.2–5.5 mm) for leachate uptake and edible size (20–770 μm) for particle ingestion and leachate uptake. Over 10 days, the HBCD concentration increased significantly in mussels in the EPS exposure groups, indicating that EPS microplastic acts as a source of HBCD to mussels. The concentration and isomeric profiles of HBCD in mussels show that uptake through the aqueous phase is a more significant pathway for bioaccumulation of HBCD from EPS to mussels than particle ingestion. HBCD levels measured in EPS, leachate and exposed mussels from this study are environmentally relevant concentration. The fate and effects of chemical additives leached from plastic debris in ecosystem requires further investigation, as it may affect numerous environments and organisms through the aqueous phase.

Polycyclic aromatic hydrocarbons (PAHs) are important organic pollutants in the aquatic environment due to their persistence and bioaccumulation potential both in organisms and in sediments. Benzo(a)anthracene (BaA) and phenanthrene (PHE), which are in the priority pollutant list of the U.S. EPA (Environmental Protection Agency), are selected as model compounds of the present study. Bioaccumulation and depuration experiments with local Mediterranean mussel species, Mytilus galloprovincialis were used as the basis of the study. Mussels were selected as bioindicator organisms due to their broad geographic distribution, immobility and low enzyme activity. Bioaccumulation and depuration kinetics of selected PAHs in Mytilus galloprovincialis were described using first order kinetic equations in a three compartment model. The compartments were defined as: (1) biota (mussel), (2) surrounding environment (seawater), and (3) algae (Phaeodactylum tricornutum) as food source of the mussels. Experimental study had been performed for three different concentrations. Middle concentration of the experimental data was used as the model input in order to represent other high and low concentrations of selected PAHs. Correlations of the experiment and model data revealed that they are in good agreement. Accumulation and depuration trend of PAHs in mussels regarding also the durations can be estimated effectively with the present study. Thus, this study can be evaluated as a supportive tool for risk assessment in addition to monitoring studies.

With the technological advances and economic development, the multiplicity and wide variety of applications of electrical and electronic equipment have increased, as well as the amount of end-of-life products (waste of electrical and electronic equipment, WEEE). Accompanying their increasing application, there is an increasing risk to aquatic ecosystems and inhabiting organisms. Among the most common elements present in WEEE are rare earth elements (REE) such as Dysprosium (Dy). The present study evaluated the metabolic and oxidative stress responses of mussels Mytilus galloprovincialis exposed to an increasing range of Dy concentrations, after a 28 days experimental period. The results obtained highlighted that Dy was responsible for mussel’s metabolic increase associated with glycogen expenditure, activation of antioxidant and biotransformation defences and cellular damage, with a clear loss of redox balance. Such effects may greatly impact mussel’s physiological functions, including reproduction capacity and growth, with implications for population conservation. Overall the present study pointed out the need for more research on the toxic impacts resulting from these emerging pollutants, especially towards marine and estuarine invertebrate species.

Trichloropropyl phosphate (TCPP) is a halogenated organophosphate ester that is widely used as flame retardants and plasticizers. In this study, gender-specific accumulation and responses in mussel Mytilus galloprovincialis to TCPP exposure were focused and highlighted. After TCPP (100 nmol L⁻¹) exposure for 42 days, male mussels showed similar average bioaccumulation (37.14 ± 6.09 nmol g⁻¹ fat weight (fw)) of TCPP with that in female mussels (32.28 ± 4.49 nmol g⁻¹ fw). Proteomic analysis identified 219 differentially expressed proteins (DEPs) between male and female mussels in control group. There were 52 and 54 DEPs induced by TCPP in male and female mussels, respectively. Interestingly, gender-specific DEPs included 37 and 41 DEPs induced by TCPP in male and female mussels, respectively. The proteomic differences between male and female mussels were related to protein synthesis and degradation, energy metabolism, and functions of cytoskeleton and motor proteins. TCPP influenced protein synthesis, energy metabolism, cytoskeleton functions, immunity, and reproduction in both male and female mussels. Protein-protein interaction (PPI) networks indicated that protein synthesis and energy metabolism were the main biological processes influenced by TCPP. However, DEPs involved in these processes and their interaction patterns were quite different between male and female mussels. Basically, twelve ribosome DEPs which directly or indirectly interacted were found in protein synthesis in TCPP-exposed male mussels, while only 3 ribosome DEPs (not interacted) in TCPP-exposed female mussels. In energy metabolism, only 4 DEPs (with the relatively simple interaction pattern) mainly resided in fatty acid metabolism, butanoate/propanoate metabolism and glucose metabolism were discovered in TCPP-exposed male mussels, and more DEPs (with multiple interactions) functioned in TCA cycle and pyruvate/glyoxylate/dicarboxylate metabolism were found in TCCP-exposed female mussels. Taken together, TCPP induced gender-specific toxicological effects in mussels, which may shed new lights on further understanding the toxicological mechanisms of TCPP in aquatic organisms.

Considering the increasing use of Lithium (Li) and the necessity to fulfil this demand, labile Li occurrence in the environment will be enhanced. Thus, additional research is needed regarding the presence of this element in marine environment and its potential toxic impacts towards inhabiting wildlife. The aim of the present study was to evaluate Li toxicity based on the exposure of Mytilus galloprovincialis to this metal, assessing the biochemical changes related with mussels’ metabolism, oxidative stress and neurotoxicity. For this, organisms were exposed to different Li concentrations (100, 250, 750 μg/L) for 28 days. The results obtained clearly demonstrated that Li lead to mussels’ metabolism depression. The present study also revealed that, especially at the highest concentrations, antioxidant and biotransformation enzymes were not activated, leading to the occurrence of lipid peroxidation and loss of redox homeostasis, with increased content in oxidized glutathione in comparison to the reduced form. Furthermore, after 28 days, higher Li exposure concentrations induced neurotoxic effects in mussels, with a decrease in acetylcholinesterase enzyme activity. The responses observed were closely related with Li concentrations in mussels’ tissues, which were more pronounced at higher exposure concentrations. Such results highlight the potential toxic effects of Li to marine species, which may even be higher under predicted climate changes and/or in the presence of other pollutants.

Microplastics (MP) are omnipresent contaminants in the oceans, however little is known about the MP transfer between marine compartments and species. Three connected laboratory experiments using the filter-feeding mussel Mytilus galloprovincialis and the omnivorous polichaete Hediste diversicolor were conducted to evaluate whether the filtering action by mussels affects the vertical transfer of MP of different sizes (MPSMALL = 41 μm; MPLARGE = 129 μm) and densities (polyamide = 1.15 g cm⁻³; polypropylene = 0.92 g cm⁻³) across compartments and species with different feeding modes. Mussels significantly removed MP from the water column by incorporating them into biodeposits. This effect was particularly evident for the MPSMALL, whose deposition from the water column to the bottom was enhanced (about 15%) by the action of mussels. The incorporation of MP into faecal pellets increased the particles’ sinking velocity by about 3–4 orders of magnitude. Conversely, the MP presence significantly decreased the depositional velocities of faecal pellets, and the magnitude of this effect was greater with increasing MP size and decreasing density. The MP incorporation into mussels’ biodeposits also more than doubled the amount of MP uptake by H. diversicolor. We conclude that detrital pathways could be a transfer route of MP across marine compartments and food webs, potentially affecting the distribution of MP in sediments and creating hot-spots of bioavailable MP.

Plastic debris has been recognized as a growing threat to marine biota due to its widespread distribution and possible interactions with marine species. Concerns over the effects of plastic polymers in marine ecosystems is reflected in the high number of toxicological studies, regarding microplastics (<5 mm) and marine fauna. Although several studies reported that organisms ingest and subsequently eliminate microplastics (MP), the potential effects at organ and tissue level remain unclear, especially considering exposure to different microplastic sizes and concentrations. The present study aimed at investigating potential pathophysiological effects of the ingestion of MP by marine filter-feeders. For the purpose, Mediterranean mussel (Mytilus galloprovincialis) was exposed to spherical polystyrene MP (2 and 10 μm Ø) over short- and medium-term exposure periods, under single and combined concentrations that represent high, yet realistic doses (10 and 1000 MP mL−1). Overall, results suggest rapid MP’ clearance from water column by filtering, regardless of MP size. Ingestion occurred, identified by MP in the lumen of the gut (mostly in midgut region), followed by excretion through faeces. However, no MP were found in gills or digestive gland diverticula. Biochemical indicators for oxidative stress were generally irresponsive regardless of organ and time of exposure. Small foci of haemocytic infiltration in gastric epithelia were found, albeit not clearly related to MP ingestion. Globally, no evident histopathological damage was recorded in whole-body sections of exposed animals. The present findings highlight the adaptative ability of filter-feeding bivalves to cope with filtration of suspended MP, resulting in rapid elimination and reduced internal damage following ingestion of spherical MP. Nevertheless, the fact that the animals are able to translocate MP to the gut reveals that filter feeding organisms may indeed became a target of concern for fragmented materials with smaller, mixed sizes and sharper edges.