Short-Term Exposure to Storm-Like Scenario Microplastic and Salinity Conditions Does not Impact Adult Sea Urchin (Arbacia punctulata) Physiology

Microplastics and Co-pollutants in Soil and Marine Environments: Sorption and Desorption Dynamics in Unveiling Invisible Danger and Key to Ecotoxicological Risk Assessment

Microplastics (MPs) and their co-pollutants pose significant threats to soil and marine environments, necessitating understanding of their colonization processes to combat the plastic pandemic and protect ecosystems. MPs can act as invisible carriers, concentrating and transporting pollutants, leading to a more widespread and potentially toxic impact than the presence of either MPs or the pollutants alone. Analyzing the sorption and desorption dynamics of MPs is crucial for understanding pollutants amplification and predicting the fate and transport of pollutants in soil and marine environments. This review provides an in-depth analysis of the sorption and desorption dynamics of MPs, highlighting the importance of considering these dynamics in ecotoxicological risk assessment of MPs pollution. The review identifies limitations of current frameworks that neglect these interactions and proposes incorporating sorption and desorption data into robust frameworks to improve the ability to predict ecological risks posed by MPs and co-pollutants in soil and marine environments. However, failure to address the interplay between sorption and desorption can result in underestimation of the true impact of MPs and co-pollutants, affecting livelihoods and agro-employments, and exacerbate poverty and community disputes (SDGs 1, 2, 3, 8, 9, and 16). It can also affect food production and security (SDG 2), life below water and life on land (DSGs 14 and 15), cultural practices, and natural heritage (SDG 11.4). Hence, it is necessary to develop new approaches to ecotoxicological risk assessment that consider sorption and desorption processes in the interactions between the components in the framework to address the identified limitations.

Transgenerational effects of microplastics on Nrf2 signaling, GH/IGF, and HPI axis in marine medaka Oryzias melastigma under different salinities

Little information is available on the toxicity of microplastics (MPs) under different salinities in aquatic organisms. Consequently, the effects of larvae exposure to 180 μg/L MPs with 5.0 μm diameter on growth, antioxidant capacity and stress response were investigated in exposed F1 larvae and unexposed F2 larvae in marine medaka Oryzias melastigma at 5 ‰ and 25 ‰ salinities. Poor growth performance of F1 and F2 larvae and F1 adult fish was merely found under high salinity, as well as changes in the growth hormone/insulin-like growth factor-I (GH/IGF). Although malondialdehyde (MDA) content and antioxidant capacity remained constant in F1 larvae under high salinity, MPs increased MDA content and reduced antioxidant capacity in F2 larvae. Contrarily, MDA and antioxidant capacity increased in F1 and F2 larvae under low salinity. The mRNA expression levels of genes in the NF-E2-related factor 2 (Nrf2) pathway were dysregulated. Cortisol levels in the whole body increased in F1 larvae and recovered to the control level under low salinity while cortisol levels declined in F1 larvae and increased in F2 larvae under high salinity, which was related to the transcriptional regulation of the hypothalamus-pituitary-interrenal (HPI) axis genes. To summary, the present study determined the toxic effects of MPs on growth, antioxidant capacity, and stress response by disturbing Nrf2, HPI, and GH/IGF signaling in exposed larvae and unexposed offspring of marine medaka in a salinity-dependent manner. For the first time, our results highlight the interference effects of salinity on MPs toxicity in fish.

Combined effects of salinity and polystyrene microplastics exposure on the Pacific oysters Crassostrea gigas: Oxidative stress and energy metabolism

Microplastics (MPs) pollution and salinity variation are two environmental stressors, but their combined effects on marine mollusks are rarely known. Oysters (Crassostrea gigas) were exposed to 1 × 10⁴ particles L^-1 spherical polystyrene MPs (PS-MPs) of different sizes (small polystyrene MPs (SPS-MPs): 6 μm, large polystyrene MPs (LPS-MPs): 50-60 μm) under three salinity levels (21, 26, and 31 psu) for 14 days. Results demonstrated that low salinity reduced PS-MPs uptake in oysters. Antagonistic interactions between PS-MPs and low salinity mainly occurred, and partial synergistic effects were mainly induced by SPS-MPs. SPS-MPs induced higher lipid peroxidation (LPO) levels than LPS-MPs. In digestive glands, low salinity decreased LPO levels and glycometabolism-related gene expression, which was related to salinity levels. Low salinity instead of MPs mainly affected metabolomics profiles of gills through energy metabolism and osmotic adjustment pathway. In conclusion, oysters can adapt to combined stressors through energy and antioxidative regulation.

Slow and steady hurts the crab: Effects of chronic and acute microplastic exposures on a filter feeder crab

Microplastics are a widespread environmental contaminant. Although detrimental effects on aquatic organisms are well documented, little is known about the long-term effects of microplastic exposure to filter-feeding organisms at ecologically realistic levels. This study investigates the effects of environmentally relevant concentrations of polyethylene micro beads ranging in size from 3 to 30 μm, on the physiology and energetics of a coastal filter-feeding crab Petrolisthes laevigatus. We evaluated the impact of microplastics by exposing P. laevigatus to two different concentrations and exposure times: i) a chronic exposure for five months at 250 particles L^-1, and ii) an acute exposure for 48 h at 20,800 particles L^-1, ~80 times higher than the chronic exposure. The results showed that only chronic exposures elicited negative effects on the coastal crab in both, metabolic and physiological parameters. Our findings demonstrate a strong correlation between the ingestion rate and weight loss, even at low concentrations, the crabs exhibited severe nutritional damage as a result of long-term microplastic exposure. By contrast, acute exposure revealed no significant effects to the crabs, a possible explanation for this being short-term compensatory responses. These results suggest that environmentally relevant concentrations of microplastics are harmful to marine organisms, and they should be evaluated during realistic temporal scales, as their effects strongly dependent on the exposure time. Our results also suggest that the effects of microplastics have been likely underestimated to date, due to the dominance of short-term exposures (acute) reported in the current literature.

Physical and chemical threats posed by micro(nano)plastic to sea urchins

The awareness of the plastic issue is rising in recent years. Our seas and coastal seawaters are investigated with the aim to evaluate the possible fate, behavior and the impact of these novel contaminants upon marine biota. In particular, benthic organisms are exposed to micro(nano)plastics that sink and accumulated on the seabed. Sea urchins can be prone to the plastic impact for all their lifespan with effect that can be extended upon the trophic cascade since their key role as grazer organisms. Moreover, they are largely used in the assessment of contaminant impact both as adult individuals and as early larval stages. This review analyzes the recent literature about the chemical and physical hazards posed by diverse polymers to sea urchins, in relation to their peculiar characteristics and to their size. The search was based on a query of the keyword terms: microplastic _ OR nanoplastic_AND Sea urchins in Web of Science and Google Scholar. The effects provoked by exposure of different sea urchin biological form are highlighted, considering both laboratory exposure and collection in real world. Additional focus has also been given upon the exposure methods utilized in laboratory test and in the existing limitations in the testing procedures. In conclusion, the micro(nano)plastics major impact seemed to be attributable to leaching compounds, however variability and lacking of realisms in the procedures do not allow a full understanding of the hazard posed by micro(nano)plastics for sea urchins. Finally, the work provides insights into the future research strategies to better characterize the actual risk for sea urchins.

Seeking for a perfect (non-spherical) microplastic particle - The most comprehensive review on microplastic laboratory research

In recent decades, much attention has been paid to microplastic pollution, and research on microplastics has begun to grow exponentially. However, microplastics research still suffers from the lack of standardized protocols and methods for investigation of microplastics under laboratory conditions. Therefore, in this review, we summarize and critically discuss the results of 715 laboratory studies published on microplastics in the last five years to provide recommendations for future laboratory research. Analysis of the data revealed that the majority of microplastic particles used in laboratory studies are manufactured spheres of polystyrene ranging in size from 1 to 50 µm, that half of the studies did not characterize the particles used, and that a minority of studies used aged particles, investigated leaching of chemicals from microplastics, or used natural particles as a control. There is a large discrepancy between microplastics used in laboratory research and those found in the environment, and many laboratory studies suffer from a lack of environmental relevance and provide incomplete information on the microplastics used. We have summarized and discussed these issues and provided recommendations for future laboratory research on microplastics focusing on (i) microplastic selection, (ii) microplastic characterization, and (iii) test design of laboratory research on microplastics.

Responses to environmentally relevant microplastics are species-specific with dietary habit as a potential sensitivity indicator

There is a lack of information on understanding how marine organisms respond to environmentally relevant microplastics (MP) which hampers decision making for waste management strategies. This study addresses this information gap by determining whether responses to MPs are species specific within a functional group. Benthic residing sea urchins, Psammechinus miliaris and Paracentrotus lividus were used as a case study. Psammechinus miliaris are strong omnivores with dietary intake including hard components (e.g. shell, tubeworms) and therefore likely to cope with the ingestion of MPs, while P. lividus are strong herbivores consuming softer dietary items (e.g. biofilms, algae) and therefore more likely sensitive. Responses to environmentally relevant MPs were conducted across two trials. Trial one determined the impact of short term (24 h) external exposure to storm-like sediment resuspension of MP concentrations (53 μm polyvinyl chloride (PVC) 25,000 MP L^-1) compared to a control without MPs. No significant impacts were observed for both P. lividus and P. miliaris on metabolic rate or righting time, and urchins were able to remove MPs from the body surface using pedicellariae and cilia. Trial two determined the impact of medium term (2 months) ingestion of a diet laced with PVC MPs (59 μm) at an inclusion rate of 0.5% mass and a control diet (without MPs) on somatic growth and animal condition. The ingestion of MPs did not significantly impact P. miliaris but significantly reduced the alimentary index within P. lividus, indicating a compromised nutritional state. This study shows that responses to microplastics are species-specific and therefore cannot be generalized. Furthermore, feeding habit could act as a potential indicator for sensitivity to MP ingestion which will be important for impact assessments of plastic pollution and management strategies.

Microplastic's story

The problem of microplastic pollution is now the order of the day in front of everyone's eyes affecting the environment and the health of leaving creature. This work aims to retrace the history of microplastics in a critical way through a substantial bibliographic collection, defining the points still unresolved and those that can be resolved. Presence of marine litter in different environments is reviewed on a global scale, focusing in particular on micro and macro plastics definition, classification and characterization techniques.

Microplastics in specific tissues of wild sea urchins along the coastal areas of northern China

Sea urchins serve as an essential niche for benthic ecosystems and are valuable seafood for humans. However, little is known about the microplastics (MPs) accumulation in sea urchins. Here, we investigated the abundances and characteristics of MPs in specific tissues of wild sea urchins for 12 sites across 2, 900 km of coastlines in northern China. Sea urchins from all sites were detected to have MPs, with a total detection rate of 89.52%. The MPs abundance in sea urchins from all sites ranged from 2.20 ± 1.50 to 10.04 ± 8.46 items/individual or 0.16 ± 0.09 to 2.25 ± 1.68 items/g wet weight. The samples from Dalian were found to have the highest value by individual, and samples from Lianyungang had the highest value by gram. Furthermore, MPs were found in different tissues of sea urchins, i.e., gut, coelomic fluid and gonads. The highest abundance of MPs was found in the gut of sea urchins, followed by coelomic fluid and gonads. The size of MPs ranged from 27 to 4742 μm, and the mean size found in gut was bigger than coelomic fluid and gonads. More interestingly, the MPs abundance increased with the decrease of anus size, shell diameter and gonad index (the wet weight ratio of gonad to total soft tissues). The MPs were dominated by fiber in shape, blue-green in colour and cellophane in composition. The high MPs abundance in sea urchins indicates the potential risks to human as they are consumed in many parts of the world, particularly in Asia and Europe.