Search

Increased production of engineered nanoparticles (NPs) has raised extensive concerns about the potential toxic effects on marine organisms. Extensive evidences documented the impact of ocean acidification (OA) on the physiology and fitness of bivalves. In the present study, we investigated the biochemical responses of the mussel Mytilus coruscus exposed to both nano-ZnO and low pH relevant for ocean acidification conditions for 14 d followed by a 7-d recovery period. Most biochemical indexes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), acid phosphatase (ACP) and alkaline phosphatase (ALP)) measured in gills and hemocytes were increased when the mussels were subject to low pH or high concentration of nano-ZnO, suggesting oxidative stress responses. No significant interactions between the two stressors were observed for most measured parameters. After a 1 week recovery period, low pH and nano-ZnO had less marked impact for SOD, GPx, ACP and ALP in hemocytes as compared to the end of the 14 d exposure. However, no recovery was observed in gills. Overall, our results suggest that both low pH and nano-ZnO induce an anti-oxidative response in Mytilus coruscus with gills being more sensitive than hemocytes.

Both nanoparticles (NPs) and ocean acidification (OA) pose threats to marine animals as well as marine ecosystems. The present study aims to evaluate the combined effects of NPs and OA on specific dynamic action (SDA) of mussels. The thick shell mussels Mytilus coruscus were exposed to two levels of pH (7.3 and 8.1) and three concentrations of TiO

With the development of nanotechnology and increased nanomaterial application, TiO

Plastic particles are thought to accumulate in aquatic organisms and cause potential physiological effects. The uneven sizes of plastic particles may affect the ingestion by marine filter feeding bivalves and may lead to differential further physiological effects. To tackle this scientific question, we investigated the size dependent ingestion and dynamic accumulation of nano/micro plastic particles with different diameters (0.07, 0.5, 5, 10 and 100 μm) in the thick shell mussel Mytilus coruscus. The accumulation of particles in gill, digestive tract and mantle of mussels was measured after 3, 15, 87 hours exposure and following 87 hours depuration. The results showed that particle ingestion was negatively size dependant and positively related to time in digestive tract. In mantle, particles accumulated over the depuration time with a delay, indicating the translocation of particles. Moreover, our results showed that gill was not a target tissue for steady particle accumulation but the digestive tract was. This study showed size dependent and dynamic ingestion of nano/micro particles in mussels which are one of the main marine organisms for accumulating microplastics.

Global change and anthropogenic activities have driven marine environment changes dramatically during the past century, and hypoxia, acidification and warming have received much attention recently. Yet, the interactive effects among these stressors on marine organisms are extremely complex and not accurately clarified. Here, we evaluated the combined effects of low dissolved oxygen (DO), low pH and warming on the digestive enzyme activities of the mussel Mytilus coruscus. In this experiment, mussels were exposed to eight treatments, including two degrees of pH (8.1, 7.7), DO (6, 2 mg/l) and temperature (30 °C and 20 °C) for 30 days. Amylase (AMS), lipase (LPS), trypsin (TRY), trehalase (TREH) and lysozyme (LZM) activities were measured in the digestive glands of mussels. All the tested stress conditions showed significant effects on the enzymatic activities. AMS, LPS, TRY, TREH showed throughout decreased trend in their activities due to low pH, low DO, increased temperature and different combinations of these three stressors with time but LZM showed increased and then decreased trend in their activities. Hypoxia and warming showed almost similar effects on the enzymatic activities. PCA showed a positive correlation among all measured biochemical parameters. Therefore, the fitness of mussel is likely impaired by such marine environmental changes and their population may be affected under the global change scenarios.

Both nanoparticles (NPs) and ocean acidification (OA) pose threats to marine animals as well as marine ecosystems. The present study aims to evaluate the combined effects of NPs and OA on specific dynamic action (SDA) of mussels. The thick shell mussels Mytilus coruscus were exposed to two levels of pH (7.3 and 8.1) and three concentrations of TiO2 NPs (0, 2.5, and 10 mg L−1) for 14 days followed by a 7-day recovery period. The SDA parameters, including standard metabolic rate, peak metabolic rate, aerobic metabolic scope, SDA slope, time to peak, SDA duration and SDA, were measured. The results showed that TiO2 NPs and low pH significantly affected all parameters throughout the experiment. When the mussels were exposed to seawater acidification or TiO2 NPs conditions, standard metabolic rate, aerobic metabolic scope, SDA slope and SDA significantly decreased, whereas peak metabolic rate, time to peak and SDA duration significantly increased. In addition, interactive effects between TiO2 NPs and pH were observed in SDA parameters except time to peak and SDA. Therefore, the synergistic effect of TiO2 NPs and low pH can adversely affect the feeding metabolism of mussels.

With the development of nanotechnology and increased nanomaterial application, TiO2 nanoparticles have been released into the aquatic environment, causing potential ecotoxicological effects on aquatic organisms. Ocean acidification caused by anthropogenic CO2 is one of the most common environmental stressors, occurring simultaneously with marine contaminants, e.g., nanoparticles. Marine bivalves can accumulate nanoparticles and their digestive functions may be affected. In this study, we investigated the potential influences of TiO2 nanoparticles on the digestive enzyme activities of marine mussels Mytilus coruscus under ocean acidification. Mussels were exposed to combined treatments with three concentrations of nano-TiO2 (0, 2.5, 10 mg/L) and two pH values (8.1, 7.3) for 14 days, and then recovered under ambient condition (pH 8.1 and no nanoparticle) for 7 days. Samples were taken on the 1st, 3rd, 7th, 14th, and 21st day, the digestive enzymes, including amylase, pepsin, trypsin, lipase, and lysozyme, were investigated. Our results showed that nano-TiO2 and low pH had negative effects on amylase, pepsin, trypsin, and lipase, while both of them led an increase in lysozyme activity. Nano-TiO2 showed greater effects on the digestive capacity of M. coruscus rather than low pH. Moreover, a recovery period of 7 days was not sufficient for these enzymes to fully recover.

Hypoxia and ocean acidification are two consequences of anthropogenic activities. These global trends occur on top of natural variability. In environments such as estuarine areas, short-term acute pH and O2 fluctuations are occurring simultaneously. The present study tested the combined effects of short-term seawater acidification and hypoxia on the physiology and energy budget of the thick shell mussel Mytilus coruscus. Mussels were exposed for 72 h to six combined treatments with three pH levels (8.1, 7.7 and 7.3) and two dissolved oxygen (DO) levels (2 mg L−1, 6 mg L−1). Clearance rate (CR), food absorption efficiency (AE), respiration rate (RR), ammonium excretion rate (ER), O:N ratio and scope for growth (SFG) were significantly reduced, and faecal organic dry weight ratio (E) was significantly increased at low DO. Low pH did not lead to a reduced SFG. Interactive effects of pH and DO were observed for CR, E and RR. Principal component analysis (PCA) revealed positive relationships among most physiological indicators, especially between SFG and CR under normal DO conditions. These results demonstrate that Mytilus coruscus was sensitive to short-term (72 h) exposure to decreased O2 especially if combined with decreased pH levels. In conclusion, the short-term oxygen and pH variation significantly induced physiological changes of mussels with some interactive effects.

Bloom forming algae and hypoxia are considered to be two main co-occurred stressors associated with eutrophication. The aim of this study was to evaluate the interactive effects of harmful algae Microcystis aeruginosa and hypoxia on an ecologically important mussel species inhabiting lakes and reservoirs, the triangle sail mussel Hyriopsis cumingii, which is generally considered as a bio-management tool for eutrophication. A set of antioxidant enzymes involved in immune defence mechanisms and detoxification processes, i.e. glutathione-S-transferases (GST), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), lysozyme (LZM) in mussel haemolymph were analyzed during 14days exposure along with 7days depuration duration period. GST, GSH, SOD, GPX and LZM were elevated by toxic M. aeruginosa exposure, while CAT activities were inhibited by such exposure. Hypoxia influenced the immune mechanisms through the activation of GSH and GPX, and the inhibition of SOD, CAT, and LZM activities. Meanwhile, some interactive effects of M. aeruginosa, hypoxia and time were observed. Independently of the presence or absence of hypoxia, toxic algal exposure generally increased the five tested enzyme activities of haemolymph, except CAT. Although half of microcystin could be eliminated after 7days depuration, toxic M. aeruginosa or hypoxia exposure history showed some latent effects on most parameters. These results revealed that toxic algae play an important role on haemolymph parameters alterations and its toxic effects could be affected by hypoxia. Although the microcystin depuration rate of H. cumingii is quick, toxic M. aeruginosa and/or hypoxia exposure history influenced its immunological mechanism recovery.