Intraspecific genetic lineages of a marine mussel show behavioural divergence when exposed to microplastic leachates

Worldwide, microplastic pollution has numerous negative implications for marine biota, exacerbating the effects of other forms of global anthropogenic disturbance. Mounting evidence shows that microplastics (MPs) not only cause physical damage through their ingestion, but also act as vectors for hazardous compounds by leaching absorbed and adsorbed chemicals. Research on the effects of plastic pollution has, however, largely assumed that species respond uniformly, while ignoring intraspecific diversity (i.e., variation within a single species). We investigated the effects of plastic leachates derived from factory-fresh (virgin) and beached microplastics on the behavioural responses of two genetic lineages of the Mediterranean mussel Mytilus galloprovincialis. Through laboratory behavioural experiments, we found that during exposure to leachates from beached microplastics (beached MPLs), Atlantic specimens moved significantly less than Mediterranean individuals in terms of both (i) proportion of individuals responding through movement and (ii) net and gross distances crawled. In contrast, no significant intraspecific differences were observed in the behaviour of either adults or recruits when exposed to MPLs from virgin microplastics (virgin MPLs). Additionally, the reception of cues from three amino acids (L-cysteine, proline and L-leucine) at increasing concentrations (10-5 M to 10-3 M in charcoal-filtered seawater) was tested by electrophysiological analysis using mussels exposed to beached MPLs or control seawater. We found significant intraspecific differences in response to 10-3 M L-cysteine (regardless of treatment) and 10-4 M L-cysteine (in mussels exposed to beached MPLs) and to 10-3 M proline (in mussels exposed to beached MPLs) and 10-5 M L-leucine. Our study suggests that intraspecific variation in a marine mussel may prompt different responses to plastic pollution, potentially triggered by local adaptation and physiological variability between lineages. Our work highlights the importance of assessing the effects of intraspecific variation, especially in environmental sentinel species as this level of diversity could modulate responses to plastic pollution.

Beached microplastics at the Bahia Blanca Estuary (Argentina): Plastic pellets as potential vectors of environmental pollution by POPs

Microplastics (MPs) from the coastal areas of a highly anthropised estuary were sampled to assess their distribution in coastal sediments and their role as potential vectors of pollution. The average MP density was 1693 ± 2315 MPs/kg, which mainly accumulated in the high tide and storm berm areas of the beach. The Microplastic Pollution Index (MPPI), Microplastic Impact Coefficient (CMPI), Hierarchical Cluster Analysis and Principal Component Analysis revealed spatial variation in MPs pollution. High-density polyethylene plastic pellets were abundant at two beaches (192 ± 218 MPs/kg sediment). Furthermore, the presence of sorbed chemicals on pellets was assessed through GC-MS, showing 0.95 ± 0.09 ng/g of ∑7OCPs, 4.03 ± 0.89 ng/g of ∑7PCBs, 108.76 ± 12.88 ng/g of ∑16 PAHs and 122.79 ± 11.13 g/g of ∑29 PAHs. The sorption capacity of plastics, combined with their abundance, poses an environmental concern and also highlights their suitability as indicators of chemical exposure.

A comprehensive investigation of industrial plastic pellets on beaches across the Laurentian Great Lakes and the factors governing their distribution

Industrial, pre-consumer pellets are a major type of plastics pollution found on shorelines worldwide. This study investigates the distribution and characteristics of plastic pellets accumulated on beaches of the Laurentian Great Lakes of North America and provides a "snapshot" of pellet distribution in a lake system that accounts for 21% of the world's freshwater reserves. We sampled pellets simultaneously from 10m² quadrats on 66 beaches and characterized the 12,595 pellets collected (average of 19.1 pellets/m²). Forty-two beaches contained pellets and 86% of the pellets were found on three beaches: Rossport (Lake Superior), Baxter (Lake Huron), and Bronte (Lake Ontario). The number of pellets on each beach was compared with factors hypothesized to control their accumulation. In general, positive correlations were found between pellet abundance and watershed population, number of plastic-related industries, and proximity to a river mouth, although for Lake Superior, abundance was related to a train spill that took place over 10 years ago. Beach grain size appears to be related to pellet abundance, with very fine sand, fine sand and medium sand containing the greatest number of pellets. All pellets were visually characterized based on size, color, shape, weathering, and distinguishing traits. The predominant color was white, oblate shapes were most common, and the main distinguishing trait was a dimple. Most pellets showed little evidence of weathering, with the weathered samples mainly from Lakes Erie and Ontario. Lake Ontario pellets were the most varied, with 6/7 shapes, 35/40 colors, and 21/25 distinguishing traits, indicating a wider range of pellet sources compared to the other lakes. Polymer compositions were mainly polyethylene (PE) and polypropylene (PP). Our results will lead to increased recognition of regional pellet pollution in the Great Lakes watershed, thereby motivating change during their production, transport and use.

Characteristics of microplastics on two beaches affected by different land uses in Salamina Island in Saronikos Gulf, east Mediterranean

In the present study, samples were taken from two beaches of the Salamina Island. The results of microplastics characterization agree well with the predicted results based on the land uses both locally and from across the mainland. The first beach, Psili Ammos, is affected by increased anthropogenic and industrial activity. Based on the Attenuated Total Reflectance (ATR) - Fourier Transform Infra-Red spectroscopy (FTIR) analysis mainly polyethylene (PE) fragments are observed than in the second beach, Kanakia. A high percentage of plastic pellets from industrial activity among fragments are found as well as the most fresh and the most degraded particles (based on the ester, keto, and vinyl indices). The second beach, Kanakia, has a high percentage of expanded polystyrene (EPS) particles suggesting an impact from fishing activities rather than industrial ones and all PE samples are found to be degraded suggesting that sources of non-fishing microplastic pollution are further away.

Levels of trace metals on microplastic particles in beach sediments of the island of Vis, Adriatic Sea, Croatia

The aim of this study was to determine the levels of trace metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in plastic pellets collected from two sandy beaches on the island of Vis, Croatia. A total of 92 pellets in a sediment volume of 3965 mL were collected at the investigated sampling sites. Concentrations of pellets in sediment samples ranged from 6 to 36 particles dm^-3 of wet sediment. Mean particle weight of the collected beached pellets ranged from 17 mg to 31 mg. Trace metal concentrations in plastic pellets were greater than the concentrations reported for seawater in the investigated area, which indicates that plastic pellets sorb metals from the marine environment. The adsorbed trace metals may enter the food chain due to incidental ingestion of microplastic particles by marine animals, which presents a potential human health risk due to consumption of seafood.

Plastic pellets, meso- and microplastics on the coastline of Northern Crete: Distribution and organic pollution

Plastic pollution in the marine environment is one of the foremost environmental problems of our time, as it affects wildlife and human health both directly and indirectly through the effects of contaminants carried by microplastics. This study investigates the temporal and spatial distribution of plastic pellets and fragments in sandy beaches along the coastline of Northern Crete, during 2013. Their densities varied throughout the year in each beach, with highest densities during the summer and towards the upper parts of the beaches. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) sorbed on microplastics sampled from nine sandy beaches of Northern Crete was quantified using Gas chromatography - Ion Trap Mass Spectrometry (GC-ITMS). PAHs concentrations ranged from non-detectable levels to 1592 ng/g and fluctuated between sampling periods. Based on the observed patterns of meso- and microplastics distribution, practical guidelines are proposed to minimize the entrance of microplastics into the seawater wherefrom they are exceptionally difficult to collect, if mitigation actions are to be applied.

Observation of the degradation of three types of plastic pellets exposed to UV irradiation in three different environments

Plastic debris represents one of the most prevalent and persistent pollution problems in the marine environment. In particular, microplastics that are mainly degraded from larger plastic debris have become a growing environmental concern. However, studies on the degradation of plastics in the aquatic environment that hydrobios reside in have been limited, while several studies regarding the degradation of plastics have been conducted under outdoor or accelerated weathering conditions. Thus, observation of the degradation of three types of virgin plastic pellets exposed to UV irradiation in three different environments (i.e., simulated seawater, ultrapure water, and a waterless (air) condition) was carried out. Data on the changes in physical and chemical properties were collected. The FTIR spectra showed that hydroxyl groups and carbonyl groups developed in three types of weathered plastic pellets under the air and ultrapure water environmental conditions after 3months of UV irradiation, while only carbonyl groups were found in plastic pellets in the simulated seawater environment. In contrast, the Raman spectra showed no significant changes in the weathered plastic pellets, but there were different intensities of characteristic peaks after exposure to UV irradiation. In addition, SEM images illustrated that granular oxidation, cracks and flakes were common patterns during degradation, and the plastic pellets in the three different environments experienced different levels of chemical weathering. We suggest that further studies on the degradation processes of plastic debris are needed to predict the fate of plastic debris in the environment.

Leachate from microplastics impairs larval development in brown mussels

Microplastic debris is a pervasive type of contaminant in marine ecosystems, being considered a major threat to marine biota. One of the problems of microplastics is that they can adsorb contaminants in extremely high concentrations. When released from the particle, these contaminants have the potential to cause toxic effects in the biota. So far, reports of toxic effects are mostly linked with the direct exposure of organisms through ingestion of contaminated microplastics. There is little information on the toxicity of leachates from microplastics to marine organisms. In this study, we conducted experiments to evaluate the toxicity of leachates from virgin and beached plastic pellets to embryo development of the brown mussel (Perna perna). We compared the efficiency of two test procedures, and evaluated the toxicity of beached pellets collected in a coastal marine protected area. We observed that mussel embryo is sensitive to leachate from both virgin and beached pellets. However, the toxicity of the leachate from beached pellets was much higher than that of virgin pellets. We suggest contaminants adsorbed onto the surface of beached pellets were responsible for the high toxicity of leachate from beached pellets, while the toxicity of leachate from virgin pellets was mainly due to plastic additives. Our results suggest microplastic debris may be harmful even if ingestion is not the only or main pathway of interaction of marine organisms with contaminated plastic debris.

Plastic pellets sorptive extraction: Low-cost, rapid and efficient extraction of polycyclic aromatic hydrocarbons from environmental waters

For the first time, plastic pellets, a low-cost and easy to reach industrial raw material, are reported as an efficient sorbent material for the laboratory extraction of polycyclic aromatic hydrocarbons (PAHs) from environmental waters. The proposed methodology, termed plastic pellets sorptive extraction (P2SE), consisted of a two-step procedure whereby target analytes were initially adsorbed onto the surface of three low-density polyethylene (LDPE) pellets and then desorbed using microliters of an organic solvent. Interphase mass transfer was greatly accelerated by means of vortex agitation. Organic extracts were analyzed by means of liquid chromatography-fluorescence detection. Different experimental parameters were controlled and the optimum conditions found were: three LDPE pellets (∼80 mg) added to 20 mL aqueous sample (20% w:v NaCl) followed by vortex agitation at 3000 rpm; for desorption, the three LDPE pellets were immersed in 100 μL of acetonitrile and the mixture was shaken at 3000 rpm for 5 min using the vortex agitator. The calculated calibration curves gave high levels of linearity yielding coefficients of determination (r(2)) greater than 0.9913. The precision of the proposed method was found to be good and the limits of the detection were calculated in the low ng L(-1) level. Matrix effects were determined by applying the proposed method to spiked river water, treated municipal wastewater and seawater samples. To compensate for the low recoveries of the more hydrophobic PAHs in spiked effluent wastewater and seawater samples the standard addition methodology was applied. The proposed method was applied to the determination of target pollutants in real seawater samples using the standard addition method. Overall, the performance of the proposed P2SE method suggests that the use of inexpensive and easy to reach sorbent materials for extracting analytes in the laboratory merits more intensive investigation.

Assessment of microplastic toxicity to embryonic development of the sea urchin Lytechinus variegatus (Echinodermata: Echinoidea)

Apart from the physiological impacts on marine organisms caused by ingesting microplastics, the toxicity caused by substances leaching from these particles into the environment requires investigation. To understand this potential risk, we evaluated the toxicity of virgin (raw) and beach-stranded plastic pellets to the development of embryos of Lytechinus variegatus, simulating transfers of chemical compounds to interstitial water and water column by assays of pellet-water interface and elutriate, respectively. Both assays showed that virgin pellets had toxic effects, increasing anomalous embryonic development by 58.1% and 66.5%, respectively. The toxicity of stranded pellets was lower than virgin pellets, and was observed only for pellet-water interface assay. These results show that (i) plastic pellets act as a vector of pollutants, especially for plastic additives found on virgin particles; and that (ii) the toxicity of leached chemicals from pellets depends on the exposure pathway and on the environmental compartment in which pellets accumulate.

Levels and fate of perfluoroalkyl substances in beached plastic pellets and sediments collected from Greece

Plastic debris damages marine wildlife and ecosystems becoming an important source of marine pollution. In addition, they can sorb, concentrate and stabilise contaminants acting as toxic carriers to the marine food web. In this context, the presence of 18 perfluoroalkyl substances (PFASs) in plastic pellets (n=5) and beach sediment (n=9) samples widely distributed around Greek coastal areas was assessed. The results, mainly, showed the sorption of PFASs onto pellet surface from surrounding water with concentrations from method limit of quantification to 115 ng/kg for C5, C7, C8 and C10 carboxylic acids and C8 sulfonate acid. A similar pattern was found by comparing plastic pellets and sediment for the same sampling locations that could indicate a common origin of contamination in both types of samples. However, since the number of analysed samples is limited, a more comprehensive study with a higher number of samples should be performed in future research.

Concentration and composition of polycyclic aromatic hydrocarbons (PAHs) in plastic pellets: implications for small-scale diagnostic and environmental monitoring

Plastic pellets may serve as a carrier of toxic contaminants, including polycyclic aromatic hydrocarbons (PAHs). Considering that beach morphodynamics and pellet distribution varied along the shore, and that contaminant sources may vary on different scales, it is expected that this variability is reflected in the concentration and composition of contaminants. This hypothesis was tested through a sampling of plastic pellets at 30 sites along the shore in Santos Bay (Brazil). The total PAH concentrations and the priority PAHs showed high variability, with no clear pattern. Their composition differed among the sampling sites; some of the compounds represent a potential risk to organisms. The sources of contamination, as indicated by the isomer ratios, were also variable among sites. The high small-scale spatial variability found here has implications for estimating the plastic pellet contamination on beaches, since a sample from a single site is unlikely to be representative of an entire beach.