Plastic pollution in the environment is increasing at global scale. Microplastics (MP) are derived from degradation of larger plastic items or directly produced in microparticles form (<5 mm). Plastics, widely used in structures and equipments of pearl farming, are a source of pollution to the detriment of the lagoon ecosystem. In order to evaluate the impact of MP on the physiology of Pinctada margaritifera, a species of ecological and commercial interests, adult oysters were exposed to polystyrene microbeads (micro-PS of 6 and 10 μm) for 2 months. Three concentrations were tested: 0.25, 2.5, 25 μg L-1 and a control. Ingestion and respiration rate and assimilation efficiency were monitored on a metabolic measurement system to determine the individual energy balance (Scope For Growth, SFG). Effects on reproduction were also assessed. The assimilation efficiency decreased significantly according to micro-PS concentration. The SFG was significantly impacted by a dose-dependent decrease from 0.25 μg L-1 (p < 0.0001). A negative SFG was measured in oysters exposed to 25 μg L-1. Gonads may have provided the missing energy to maintain animals’ metabolism through the production of metabolites derived from germ cells phagocytosis. This study shows that micro-PS significantly impact the assimilation efficiency and more broadly the energy balance of P. margaritifera, with negative repercussions on reproduction.
The rapid increase in plastic use over the last few decades has resulted in plastic pollution in freshwater and marine ecosystems. However, more attention has been paid to plastic pollution in marine ecosystems than to freshwater ecosystems. This research determined microplastic ingestion by Daphnia magna and the potential effect of microplastics on the organism’s survival and reproduction. The study also examined the potential of microplastics to enhance algal growth in support of understanding effects of microplastic ingestion on the organism. When exposed to 25, 50, and 100 mg/L fluorescent green polyethylene microbeads at size of 63–75 μm, D. magna ingested significant amount of plastic microbeads. The number of ingested beads increased with increasing particle concentration and exposure time. However, no significant effect on survival and reproduction was observed although the gut of D. magna was filled with plastic microbeads. In the algal experiment, Raphidocelis subcapitata grew more in the exposure media with the present of plastic microbeads than without plastic microbeads. This result suggests that plastic microbeads could serve as substrates for R. subcapitata to grow. Raphidocelis subcapitata then could be transferred to the organism’s gut and provided energy for survival and reproduction. Results of the present study add to the literature of microplastic ingestion by aquatic organisms. Caution should be taken when interpreting hazards of microplastics based on ingestion, such as the measurement unit and the presence of algae in the environment.
P. M. Canniff, T. C. Hoang, Science of The Total Environment, Volume 633, 15 August 2018, Pages 500–507
The need for better microplastic removal from wastewater streams is clear, to prevent potential harm the microplastic may cause to the marine life. This paper aims to investigate the efficacy of electrocoagulation (EC), a well-known and established process, in the unexplored context of microplastic removal from wastewater streams. This premise was investigated using artificial wastewater containing polyethylene microbeads of different concentrations. The wastewater was then tested in a 1 L stirred-tank batch reactor. The effects of the wastewater characteristics (initial pH, NaCl concentration, and current density) on removal efficiency were studied. Microbead removal efficiencies in excess of 90% were observed in all experiments, thus suggesting that EC is an effective method of removing microplastic contaminants from wastewater streams. Electrocoagulation was found to be effective with removal efficiencies in excess of 90%, over pH values ranging from 3 to 10. The optimum removal efficiency of 99.24% was found at a pH of 7.5. An economic evaluation of the reactor operating costs revealed that the optimum NaCl concentration in the reactor is between 0 and 2 g/L, mainly due to the reduced energy requirements linked to higher water conductivity. In regard to the current density, the specific mass removal rate (kg/kWh) was the highest for the lowest tested current density of 11 A/m2, indicating that low current density is more energy efficient for microbead removal.
The exposure of nanoplastics was investigated by observing their interaction with Amphibalanus amphitrite (commonly known as acorn barnacles). Poly(methyl methacrylate) (PMMA) and fluorescent perylene tetraester (PTE) dye were used to prepare highly fluorescent nanoplastic particles. At concentrations of 25 ppm, the PMMA particles showed no detrimental impact on barnacle larvae and their microalgae feed, Tetraselmis suecica and Chaetoceros muelleri. PMMA nanoplastics were ingested and translocated inside the body of the barnacle nauplii within the first 3 hours of incubation. The fluorescent PMMA particles inside the transparent nauplius were tracked using confocal fluorescence microscopy. Subsequently, the nanoplastics were fed to the barnacles under two conditions – acute and chronic exposure. The results from acute exposure show that nanoplastics persist in the body throughout stages of growth and development – from nauplius to cyprid and juvenile barnacle. Some egestion of nanoplastics was observed through moulting and faecal excrement. In comparison, chronic exposure demonstrates bioaccumulation of the nanoplastics even at low concentrations of the plastics. The impacts of our study using PMMA nanoparticles exceeds current knowledge, where most studies stop at uptake and ingestion. Here we demonstrate that uptake of nanoparticles during planktonic larval stages may persist to the adult stages, indicating the potential for the long-term impacts of nanoplastics on sessile invertebrate communities.
Microplastics (MPs), plastic debris smaller than 5 mm, are widely found in both marine and freshwater ecosystems. However, few studies regarding their hazardous effects on inland water organisms, have been conducted. For this reason, the aim of our research was the evaluation of uptake and chronic toxicity of two mixtures (MIXs) of virgin polystyrene microbeads (PMs) of 10 μm and 1 μm in size (MIX 1, with 5 × 105 of 1 μm size PMs/L and 5 × 105 of 10 μm size PMs/L, and MIX 2 with 2 × 106 of 1 μm size PMs/L and 2 × 106 of 10 μm size PMs/L) on freshwater zebra mussel Dreissena polymorpha (Mollusca: Bivalvia) during 6 exposure days. The PM uptake in the mussel body and hemolymph was assessed using confocal microscopy, while the chronic toxicity of PMs was evaluated on exposed mussels using a comprehensive battery of biomarkers of cellular stress, oxidative damage and neuro- genotoxicity. Confocal microscopy analyses showed that MPs concentrated in the gut lumen of exposed mussels, absorbed and transferred firstly in the tissues and then in the hemolymph. The results revealed that PMs do not produce oxidative stress and genetic damage, with the exception of a significant modulation of catalase and glutathione peroxidase activities in mussels exposed to MIX 1. Regarding neurotoxicity, we observed only a significant increase of dopamine concentration in mussels exposed to both MIXs, suggesting a possible implication of this neurotransmitter in an elimination process of accumulated PMs. This research represents a first study about the evaluation of virgin MP toxicity in zebra mussel and more research is warranted concerning the long term neurological effects of virgin MPs.
Stefano Magni, François Gagné, Chantale André and al., Science of The Total Environment, Volumes 631–632, 1 August 2018, Pages 778–788
In 2017, Prime Minister Trudeau announced five themes for Canada’s G7 presidency which began in January 2018. Under the “Working together on climate change, oceans and clean energy” theme, Canada is hosting domestic and international discussions to advance priorities specifically focusing on oceans. These discussions will bring together experts to discuss challenges and opportunities both domestically and internationally, to move toward zero plastic waste and mitigating marine plastic litter, including microplastics ( Government of Canada, 2017). Global marine litter is now recognized as one of the most widespread sources of pollution facing the world’s oceans.
Tony R. Walker, Dirk Xanthos, Resources, Conservation and Recycling, Volume 133, June 2018, Pages 99–100
Manufacturing ban means the tiny beads which harm marine life can no longer be used in cosmetics and personal care product.
Plastic microbeads can no longer be used in cosmetics and personal care products in the UK, after a long-promised ban came into effect on Tuesday. The ban initially bars the manufacture of such products and a ban on sales will follow in July. (…) (theguardian.com, 9/01/2018)