Mussel Mytilus Galloprovincialis Research Articles

The Mediterranean Mussel Mytilus galloprovincialis (Mollusca: Bivalvia) in Chile: Distribution and Genetic Structure of a Recently Introduced Invasive Marine Species.

The genetic characteristics of invasive species have a significant impact on their ability to establish and spread. The blue mussel (Mytilus galloprovincialis), native to the Mediterranean Sea, is a leading invasive species of intertidal coasts throughout much of the world. Here, we used mitochondrial DNA sequence data to investigate the genetic diversity and phylogeographic structure of invasive (M. galloprovincialis) versus native (Mytilus chilensis) populations of blue mussels in Chile. We evaluated whether genetic diversity in invasive populations could be explained by the genetic characteristics of the native sources from which they might be derived. A phylogenetic analysis confirmed two lineages of the invasive M. galloprovincialis, i.e., the NW Atlantic and the Mediterranean lineages. We found no evidence of genetic structure in the invasive range of M. galloprovincialis in Chile, most probably because of its recent arrival. We did, however, detect a spatial mixture of both M. galloprovincialis lineages at sampling locations along the Chilean coast, giving rise to higher levels of genetic diversity in some areas compared to the population of native M. chilensis. The coastal area of the invasion is still small in extent (~100 km on either side of two large ports), which supports the hypothesis of a recent introduction. Further expansion of the distribution range of M. galloprovincialis may be limited to the north by increasing water temperatures and to the south by a natural biogeographic break that may slow or perhaps stop its spread. The use of internal borders as a tool to minimise or prevent M. galloprovincialis spread is therefore a genuine management option in Chile but needs to be implemented rapidly.

Determination of lipophilic marine biotoxins (azaspiracids, brevetoxins, and okadaic acid group) and domoic acid in mussels by solid-phase extraction and reversed-phase liquid chromatography with tandem mass spectrometry

An accurate and efficient method was developed for the determination of azaspiracid shellfish toxins (azaspiracids-1, -2, and -3), neurotoxic shellfish toxins (brevetoxins-2 and -3), diarrhetic shellfish toxins (okadaic acid and dinophysistoxins-1 and -2), and the amnesic shellfish toxin (domoic acid) in mussels (Mytilus galloprovincialis). Lipophilic marine biotoxins (azaspiracids, brevetoxins, and okadaic acid group) were extracted with 0.5 % acetic acid in methanol under heating at 60°C to improve the extraction efficiency of okadaic acid group toxins and then cleaned up with a C18 solid-phase extraction cartridge. Domoic acid was extracted with 50 % aqueous methanol and then cleaned up with a graphitized carbon solid-phase extraction cartridge. Lipophilic marine biotoxins and domoic acid were quantified by reversed-phase liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The developed method had insignificant matrix effects for the nine analytes and good recoveries in the range of 79.0 % to 97.6 % at three spiking levels for all analytes except brevetoxin-2 (43.8–49.8 %). The developed method was further validated by analyzing mussel tissue certified reference materials, and good agreement was observed between certified and determined values.

Ocean acidification impact on the uptake of trace elements by mussels and their biochemical effects

This study delves into the intricate interplay between ocean acidification (OA), metal bioaccumulation, and cellular responses using mussels (Mytilus galloprovincialis) as bioindicators. For this purpose, environmentally realistic concentrations of isotopically labelled metals (Cd, Cu, Ag, Ce) were added to investigate whether the OA increase would modify metal bioaccumulation and induce adverse effects at the cellular level. The study reveals that while certain elements like Cd and Ag might remain unaffected by OA, the bioavailability of Cu and Ce could potentially escalate, leading to amplified accumulation in marine organisms. The present findings highlight a significant rise in Ce concentrations within different mussel organs under elevated pCO2 conditions, accompanied by an increased isotopic fractionation of Ce (140/142Ce), suggesting a heightened potential for metal accumulation under OA. The results suggested that OA influenced metal accumulation in the gills of mussels. Conversely, metal accumulation in the digestive gland was unaffected by OA. The exposure to both trace metals and OA affects the biochemical responses of M. galloprovincialis, leading to increased metabolic capacity, changes in energy reserves, and alterations in oxidative stress markers, but the specific effects on other biomarkers (e.g., lipid peroxidation, some enzymatic responses or acetylcholinesterase activity) were not uniform, suggesting complex interactions between the stressors and the biochemical pathways in the mussels.

An Optimized and Validated QuEChERS-Based Method for the Determination of PCBs in Edible Aquatic Species

AbstractIn the present research, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was optimized and validated for the determination of 14 selected PCB congeners in mussel (Mytilus galloprovincialis) and fish samples (Sparus aurata). The optimization included the selection of different QuEChERS procedures, extraction solvent, sample weight, and suitable sorbents for the clean-up step to achieve high sensitivity and minimal matrix interferences simultaneously. The identification and quantification of the selected PCBs were carried out using GC–MS. The method was validated providing in all cases excellent linearity (r2 above 0.99). Recoveries were estimated at three different fortification levels (10, 50, and 100 ng g−1) and ranged from 72.5 to 109.5% and 72.1 to 88.4% for mussel and fish samples, respectively. In addition, for both matrices, the LOQs ranged from 1 to 2.5 ng g−1. The matrix effect was in all cases < 29%, while the expanded uncertainty U%, which was estimated at all the fortification levels, was found below 53% in all cases. Eventually, the optimized and validated method was applied to mussel and fish samples acquired from aquacultures in NW Greece, revealing the absence of the selected congeners in all cases.

Microplastics in Mediterranean Mussel Mytilus galloprovincialis: Comparison between Cultured and WildType Mussels from the Northern Adriatic

This study aimed to assess microplastics (MPs) in the digestive glands of Mytilus galloprovincialis mussels. Mussels were collected from pristine, aquaculture, and port areas of the northern Adriatic Sea (Slovenia and Croatia coastline). MPs were detected using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The characterized MPs were further categorized based on their shape, size, and color. The highest number of 32.85 ± 27.98 MPs per mussel digestive gland was found in the mussels sampled from the ACI marina Rovinj (Croatia). The predominant MPs found in the mussel digestive glands at all investigated locations belonged to the smallest analyzed category (5–10 μm in size) and exhibited spherical and fragment shapes. The most abundant MPs found in mussels by color were white particles. MPs were found in both wild and farmed mussels and, hence, the results point out that the abundance of microplastic pollution is omnipresent along the coastal waters of the northern Adriatic Sea.

The pharmaceutical triclosan induced oxidative stress and physiological disorder in marine organism and nanoparticles as a potential mitigating tool

Environmental research plays a crucial role in formulating novel approaches to pollution management and preservation of biodiversity. This study aims to assess the potential harm of pharmaceutical triclosan (TCS) to non-target aquatic organism, the mussel Mytilus galloprovincialis. Furthermore, our study investigates the potential effectiveness of TiO2 and ZnO nanomaterials (TiO2 NPs and ZnO NPs) in degrading TCS. To ascertain the morphology, structure, and stability of the nanomaterials, several chemical techniques were employed. To evaluate the impact of TCS, TiO2 NPs, and ZnO NPs, both physiological (filtration rate (FR) and respiration rate (RR)), antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST)) activities and malondialdehyde (MDA) contents were measured in M. galloprovincialis gills and digestive gland.The mussel's responses varied depending on the contaminant, concentration, and organ, underscoring the significance of compiling these factors in ecotoxicity tests. The main toxic mechanisms of TCS and ZnO NPs at a concentration of 100 μg/L were likely to be a decrease in FR and RR, an increase in oxidative stress, and increased lipid peroxidation.Our findings indicate that a mixture of TCS and NPs has an antagonist effect on the gills and digestive gland. This effect is particularly notable in the case of TCS2 = 100 μg/L combined with TiO2 NP2 = 100 μg/L, which warrants further investigation to determine the underlying mechanism. Additionally, our results suggest that TiO2 NPs are more effective than ZnO NPs at degrading TCS, which may have practical implications for pharmaceutical control in marine ecosystems and in water purification plants. In summary, our study provides valuable information on the impact of pharmaceuticals on non-target organisms and sheds light on potential solutions for their removal from aqueous environments.

Mass Mortality Event of Mediterranean Mussels (Mytilus galloprovincialis) in the Middle Adriatic: Potential Implications of the Climate Crisis for Marine Ecosystems

The effects of the climate crisis are affecting ecosystems at different scales and magnitudes. This paper focuses on a massive Mediterranean mussel die-off observed along the middle Italian Adriatic coast in the summer of 2022. We considered the possible environmental causes of this phenomenon and carried out a climatic analysis of the last decade. We performed field surveys in different locations along a 16 km coastal stretch from Martinsicuro (TE) in the south, to Grottammare (AP) in the north. The study area includes two marine Sites of Community Importance under the European Natura 2000 network. The die-off of the mussels was observed in practically all the natural mussel beds colonizing the study area. As sessile filter-feeding organisms inhabiting the intertidal zone, mussels are highly exposed to variations in environmental conditions such as temperature and nutrient load. We discuss the possible causes of this die-off, proposing that high temperature and the scarce availability of food acted simultaneously as stress factors, generating local unsustainable living conditions for this species.

Sulfated phenolic polymers as non-toxic antifouling agents

Nature-inspired highly sulfated bioactive polyphenols are recently emerging as antifouling agents with low or non-toxic effects to the environment representing a valuable alternative to the most used harmful biocides. In this frame, we report herein the preparation of sulfated derivatives of two phenolic polymers of tyrosol and gallic acid previously obtained via a convenient horseradish peroxidase/H2O2-catalyzed oxidation process. A mild sulfation procedure based on the use of sulfur trioxide triethylamine complex under microwave irradiation afforded the corresponding sulfated polymers OligoTyrS and OligoGallS in good yields (90–95 % w/w). Elemental analysis, FT-IR and MALDI-MS investigation provided evidence for an almost complete sulfation of the –OH groups. In line with a high degree of sulfation, OligoTyrS and OligoGallS exhibited lower antioxidant properties compared to the non-sulfated polymers as evaluated by the 2,2-diphenyl-1-picrylhydrazyl and ferric reducing/antioxidant power assays. In contrast to the non-sulfated polymers, OligoTyrS and OligoGallS showed a significant inhibitory effect against the settlement of mussel (Mytilus galloprovincialis) plantigrade without lethality effects and without affecting the selected biofilm-forming organisms like five marine bacteria and a diatom. Both sulfated polymers were also found to be non-toxic to the non-target species Artemia salina. The overall results presented herein put forward the potential of non-natural sulfated phenolic polymers as new non-toxic antifouling agents.

Effects of harvesting and an invasive mussel on intertidal rocky shore communities based on historical and spatial comparisons.

Intertidal rocky shores are the most accessible marine habitats and therefore heavily impacted by harvesting. In recent years, they have also been increasingly invaded by alien species, which compounds the effects of harvesting on rocky shore community composition and functioning. Recent survey data, combined with historical data from 1970, were used to assess temporal changes over the intervening period in rocky shore communities at two sites (Wireless Point and Wireless Island). Three kinds of changes emerged: (1) the appearance of alien species; (2) the effects of increased harvesting pressure; and (3) the direct and indirect effects of these changes on other species. A striking result was transformation of mid-shore zones on exposed shores by the appearance of the invasive Mediterranean mussel Mytilus galloprovincialis, and the indirect effects of this on the demography and vertical zonation patterns of the granular limpet Scutellastra granularis. Adult limpets have become excluded by the mussel, whereas juveniles find a secondary home on the shells of the mussel and their abundance has increased. To further disentangle the effects of harvesting from those of alien invasions, a spatial comparison was made between two currently unharvested no-take sites (Scarborough South and Scarborough North) and two regularly harvested sites (Kommetjie and Wireless Point). Harvesting has substantially depleted the granite limpet Cymbula granatina and Argenville's limpet Scutellastra argenvillei. This has led to the proliferation of opportunistic seaweeds, such as Ulva spp. The dual effects of alien invasive species and over-harvesting have major ecosystem effects but do not necessarily diminish biodiversity because the alternative habitats that have developed provide opportunities for colonisation by additional species.

First characterization of the nuclear receptor superfamily in the Mediterranean mussel Mytilus galloprovincialis: developmental expression dynamics and potential susceptibility to environmental chemicals.

Endocrine-disrupting chemicals (EDCs) represent a global threat to human health and the environment. In vertebrates, lipophilic EDCs primarily act by mimicking endogenous hormones, thus interfering with the transcriptional activity of nuclear receptors (NRs). The demonstration of the direct translation of these mechanisms into perturbation of NR-mediated physiological functions in invertebrates, however, has rarely proven successful, as the modes of action of EDCs in vertebrates and invertebrates seem to be distinct. In the present work, we investigated the members of the NR superfamily in a bivalve mollusk, the Mediterranean mussel Mytilus galloprovincialis. In addition to annotating the M. galloprovincialis NR complement, we assessed the potential developmental functions and susceptibility to EDC challenge during early development by gene expression analyses. Our results indicate that a majority of mussel NRs are dynamically expressed during early development, including receptors characterized by a potential susceptibility to EDCs. This study thus indicates that NRs are major regulators of early mussel development and that NR-mediated endocrine disruption in the mussel could be occurring at a larger scale and at earlier stages of the life cycle than previously anticipated. Altogether, these findings will have significant repercussions for our understanding of the stability of natural mussel populations. This article is part of the theme issue 'Endocrine responses to environmental variation: conceptual approaches and recent developments'.

Evaluation of Health Risks Attributed to Toxic Trace Elements and Selenium in Farmed Mediterranean Mussels from Türkiye and Bulgaria.

Farmed mussels accumulate contaminants from their production environment rather than releasing them into water. This study reveals potential health risks associated with selenium, cadmium, mercury, and lead resulting from the consumption of mussels (Mytilus galloprovincialis) cultured along the coasts of Türkiye and Bulgaria. The concentrations of Se and toxic trace metals were measured by inductively coupled plasma mass spectrometry (ICP-MS). The detection limits (LOD) were 0.100, 0.015, 0.025, and 0.180µg/kg for Se, Cd, Hg, and Pb, respectively. The mean Se concentrations were between 1.305 and 1.957µg/g, and toxic metals were below the maximum limits. Due to Turkish and Bulgarian consumers' limited mollusk consumption, mussels could only provide a maximum of 7.35% of the daily Se need. THQ and TTHQ of Se, Cd, and methyl-Hg were below 1, indicating that farmed mussels were safe for consumption. Percent PTWI values were calculated only for Cd and MeHg, as the PTWI value for Pb was discarded by the authorities and not determined for Se. Accordingly, weekly mussel consumption did not pose any risks. The margin of exposure approach was used to evaluate Pb intake. MOE-SBP and MOE-NE were significantly higher than 10, designating no significant health risks. Long-term consumption of mussels also does not pose a carcinogenic risk regarding the TR index calculated between 10-5 and 10-6 for Pb. Positive HBVSe (10.13-37.27) indicated that Se in mussels overcame Hg-related potential health concerns. Consequently, mussels grown in Türkiye and Bulgaria did not pose a risk for human consumption, based on current risk analysis methods.

The response of the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819) exposed to copper-doped zinc nanoparticles

The response of the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819) exposed to copper-doped zinc nanoparticles

Real-time and non-destructive control of the freshness and viability of live mussels through portable near-infrared spectroscopy

This study introduces the application of a novel, rapid, and non-destructive method employing portable near-infrared (NIR) spectroscopy to assess the freshness and viability of live mussels throughout their shelf-life. NIR spectra ranging from 908 to 1676 nm were collected from 150 Mediterranean mussels (Mytilus galloprovincialis, L.) over a 10-day storage period. Simultaneously, measurements of weight loss, intravalvular liquid pH, and nonprotein nitrogen levels were taken. A predictive model was established by correlating the multivariate information derived from NIR spectral data with days of storage under refrigerated conditions using orthogonal partial least squares regression (OPLSR) analysis. While physical and chemical parameters (except for gradual weight loss due to water leakage) showed no distinct trends throughout storage, the fourth derivative-preprocessed NIR spectra enabled the construction of an OPLSR model that, following cross-validation, exhibited a correlation coefficient of 0.86 and, following external validation with new mussel samples, an average accuracy (root mean square error of prediction) of just 1.3 days. The predictive power of the model was primarily attributed to specific NIR wavelengths associated with key chemical features, including unsaturated fatty acids, nitrogen compounds, water content, glycerol, and ATP-related compounds that, collectively, constituted a distinctive fingerprint for forecasting mussel storage duration. The performance of the tool, along with its environmentally friendly, non-invasive, real-time, and cost-effective characteristics, align with industry control procedures and inspection needs, allowing effective freshness and viability assessment of live mussels across the food supply chain.

The odd couple: Caffeine and microplastics. Morphological and physiological changes in Mytilus galloprovincialis.

In recent years, the presence of pharmaceuticals and microplastics (MPs) in aquatic ecosystems has raised concerns about their environmental impact. This study explores the combined effects of caffeine, a common pharmaceutical pollutant, and MPs on the marine mussel Mytilus galloprovincialis. Caffeine, at concentrations of 20.0 μg L-1, and MPs (1 mg L-1, 35-50 μm size range), was used to mimic real-world exposure scenarios. Two hundred M. galloprovincialis specimens were divided into four groups: caffeine, MPs, Mix (caffeine + MPs), and Control. After a two-week acclimation period, the mollusks were subjected to these pollutants in oxygen-aerated aquariums under controlled conditions for 14 days. Histopathological assessments were performed to evaluate gill morphology. Cellular volume regulation and digestive gland cell viability were also analyzed. Exposure to caffeine and MPs induced significant morphological changes in M. galloprovincialis gills, including cilia loss, ciliary disk damage, and cellular alterations. The chitinous rod supporting filaments also suffered damage, potentially due to MP interactions, leading to hemocyte infiltration and filament integrity compromise. Hemocytic aggregation suggested an inflammatory response to caffeine. In addition, viability assessments of digestive gland cells revealed potential damage to cell membranes and function, with impaired cell volume regulation, particularly in the Mix group, raising concerns about nutrient metabolism disruption and organ function compromise. These findings underscore the vulnerability of M. galloprovincialis to environmental pollutants and emphasize the need for monitoring and mitigation efforts. RESEARCH HIGHLIGHTS: The synergy of caffeine and microplastics (MPs) in aquatic ecosystems warrants investigation. MPs and caffeine could affect gill morphology of Mytilus galloprovincialis. Caffeine-exposed cells had lower viability than the control group in the NR retention test. MPs and mix-exposed cells struggled to recover their volume.

Yttrium effects on the Mediterranean mussel under a scenario of salinity shifts and increased temperature

Climate change (CC) induces significant worldwide alterations in salinity and temperature, impacting ecosystems and their services. Marine organisms, susceptible to these changes, may experience modified vulnerability to anthropogenic contaminants, including rare-earth elements (REEs) such as yttrium (Y) derived from electronic waste. This study investigated the influence of temperature and salinity changes on the impacts of Y in Mytilus galloprovincialis mussels. Organisms were subjected to Y (0 and 10 μg/L) for 28 days under three salinity scenarios (20, 30 (control), and 40, at a control temperature of 17 °C) or to two temperatures (17 and 22 °C, at the control salinity of 30). Under these conditions, Y bioaccumulation and different biomarkers were evaluated. Results showed that salinity and temperature did not affect Y accumulation, indicating effective detoxification mechanisms and physiological adaptations in the exposed organisms. However, in Y-exposed mussels effects were intensified under decreased salinity, evidenced by increased metabolism, defense enzyme activities, and acetylcholinesterase (AChE) levels. Similar responses occurred under heat stress with enhanced metabolic capacity, AChE activity, and activation of defense mechanisms such as glutathione S-transferases. These defense mechanisms mitigated cellular damage caused by Y, but under the highest temperature and especially lower salinity, Y-exposed mussels exhibited increased oxidative stress and decreased efficiency of activated defense enzymes, resulting in cellular damage compared to their uncontaminated counterpart. The present study sheds light on the effects that interactions between temperature, salinity, and the presence of emerging contaminants like REEs may have on marine organisms. Such assessments are crucial for developing effective strategies to mitigate the impacts of CC and protect the long-term health and resilience of marine ecosystems.

How predicted temperature and salinity changes will modulate the impacts induced by terbium in bivalves?

The threat of climate change, which includes shifts in salinity and temperature, has generated a global concern for marine organisms. These changes directly impact them and may alter their susceptibility to contaminants, such as terbium (Tb), found in electronic waste. This study assessed how decreased and increased salinity, as well as increased temperature, modulates Tb effects in Mytilus galloprovincialis mussels. After an exposure period of 28 days, Tb bioaccumulation and biochemical changes were evaluated. Results indicated no significant modulation of salinity and temperature on Tb accumulation, suggesting detoxification mechanisms and adaptations. Further analysis showed that Tb exposure alone caused antioxidant inhibition and neurotoxicity. When exposed to decreased salinity, these Tb-exposed organisms activated defense mechanisms, a response indicative of osmotic stress. Moreover, increased salinity also led to increased oxidative stress and metabolic activity in Tb-exposed organisms. Additionally, Tb-exposed organisms responded to elevated temperature with altered biochemical activities indicative of damage and stress response. Such responses suggested that Tb effects were masked by osmotic and heat stress. This study provides valuable insights into the interactions between temperature, salinity, and contaminants such as Tb, impacting marine organisms. Understanding these relationships is crucial for mitigating climate change and electronic waste effects on marine ecosystems.

Evidence of internalized microplastics in mussel tissues detected by volumetric Raman imaging

Microplastics are a global ecological concern due to their potential risk to wildlife and human health. Animals ingest microplastics, which can enter the trophic chain and ultimately impact human well-being. The ingestion of microplastics can cause physical and chemical damage to the animals' digestive systems, affecting their health. To estimate the risk to ecosystems and human health, it is crucial to understand the accumulation and localization of ingested microplastics within the cells and tissues of living organisms. However, analyzing this issue is challenging due to the risk of sample contamination, given the ubiquity of microplastics. Here, an analytical approach is employed to confirm the internalization of microplastics in cryogenic cross-sections of mussel tissue. Using 3D Raman confocal microscopy in combination with chemometrics, microplastics measuring 1 μm in size were detected. The results were further validated using optical and fluorescence microscopy. The findings revealed evidence of microplastics being internalized in the digestive epithelial tissues of exposed mussels (Mytilus galloprovincialis), specifically within the digestive cells forming digestive alveoli. This study highlights the need to investigate the internalization of microplastics in organisms like mussels, as it helps us understand the potential risks they pose to aquatic biota and ultimately to human health. By employing advanced imaging techniques, challenges associated with sample contamination can be overcome and valuable insights into the impact of microplastics on marine ecosystems and human consumers are provided.

Effects of Exposure to Urban Atmospheric Particulate Matter Suspended in Seawater on the Mussel Mytilus galloprovincialis

Atmospheric particulate matter (PM) contains numerous constituents, including organic molecules, inorganic ions, and metals, with some of them possessing hazardous properties. Although mainly associated with air pollution, PM can rapidly be transferred from air and land to aquatic ecosystems, and consequently poses a risk to marine biota. The aim of this work was to evaluate how urban atmospheric PM (a standard reference mixture of urban PM, known to contain various organic and inorganic contaminants), suspended in seawater, may cause toxicity in marine organisms. To this purpose, mussels (Mytilus galloprovincialis) were exposed to two concentrations of suspended PM: 5.7 and 11.4 mg/L. After 7, 14, and 21 days, the animals were collected and the gills and digestive gland were analysed for stress biomarkers (CAT, SOD, GPX, GST, MDA, and Ubi). In general, the results show that exposure to different concentrations of PM caused an increase in GST, UBI, and GPx activities compared to their respective controls. The average activities of GST (87.65 ± 30.23 nmol/min/mg of total protein) in the gills of the animals exposed to 11.4 mg/L of PM increased after 21 days of exposure, and the activity of GPx (8.04 ± 3.09 nmol/min/mg of total protein) in the gills increased after 14 days in the animals exposed to 5.7 mg/L of PM. MDA results also provided information on cellular damage, with the most pronounced effects being found in the gills of exposed mussels. This study confirms that mussels are useful as “early warning” indicators of environmental contamination and provides important information on the effects of PM on marine biota.

Comparative responses and effects of exposure to metallic and nanoparticle zinc in the mussel Mytilus galloprovincialis

Zinc (Zn) nanoparticles (NPs) are widely used in various industrial and commercial applications. Their intensive use in sunscreens, for instance, renders priority to understanding their effects on marine life, to which may be added the intensive use of Zn-based paints and anodes to protect submerged structures. We studied the effects of Zn nanoparticles and ions in the mussel Mytilus galloprovincialis exposed to 1, 10 and 100 μg/L of both zinc forms for up to 28 days. Effects were determined by analysing a battery of biomarkers, from oxidative stress (total antioxidant capacity and catalase activity) to acetylcholinesterase (AChE) activity. The results revealed that mussels responded only marginally differently to ionic and Zn nanoparticles, but also that their response was concentration- and time-dependent, suggesting distinct metabolic modes of action. These variations occurred almost exclusively at the highest concentration tested and were more pronounced as the exposure period increased. An integrated biomarker index (IBR) approach was used encompassing also previous findings (lipid peroxidation and metal accumulation in tissue), which further confirmed that these filter-feeding organisms are considerable targets for zinc exposure in the two forms tested and should be included in studies evaluating the overall toxicological impact of various forms of Zn in the marine environment.

Short communication: ROS production and mitochondrial membrane potential in hemocytes of marine bivalves, Mytilus galloprovincialis and Magallana gigas, under hypoosmotic stress.

Bivalve mollusks that inhabit low-depth coastal and estuarine areas frequently experience osmotic stress that may be also associated with alterations of antioxidant enzyme activities and markers of oxidative stress. Mitochondria are a major source of reactive oxygen species (ROS) in eucaryotic cells. Overpoduction of ROS induces oxidative stress leading to a damage of intracellular compartments and cell death. In euryhaline bivalves, information concerning cellular ROS production upon osmotic stress and changes in mitochondrial membrane potential is scarce. The present study investigates osmotic stability and hemocytes` regulatory volume decrease (RVD) of Mediterranean mussel (Mytilus galloprovincialis) and the Pacific oyster (Magallana gigas). We also studied dynamic changes in intracellular ROS levels and mitochondrial membrane potential in hemocytes undergoing the RVD response following hypoosmotic swelling. Our data revealed that osmotic stability of mussel and oyster hemocytes did not significantly differ. Loss of environmental osmolarity from 460.0±2.0mOsml-1 to 216.0±4.0mOsml-1 resulted in an increase of hemocyte volume by 60% of the initial cellular volume in mussels and by 28% in oysters. After rapid hypoosmotic swelling hemocytes of both species demonstrated the RVD response. At the end of 60min exposure to hypoosmotic environment, hemocyte volume significantly decreased in both species by 10-12% compared to the maximal hemocyte volume. Hypoosmotic shock induced an increase of mitochondrial membrane potential in hemocytes of mussels and oysters. In mussels, increased mitochondrial membrane potential was accompanied with decreased ROS levels in hemocytes, whereas oyster hemocytes showed enhanced ROS production.