Prevalence of Microplastics in the Eastern Oyster Crassostrea virginica in the Chesapeake Bay: The Impact of Different Digestion Methods on Microplastic Properties

Microplastic contamination of intertidal sediment and cockles (Cerastoderma edule)

Microplastic pollution represents a new threat to both marine environments and the species that reside within them. This study examined the temporal concentrations of microplastics found in the commercially and ecologically important bivalve, Cerasastoderma edule and the presence of microplastics in intertidal sediment from the Special Area of Conservation (SAC) and Special Protected Area (SPA) of Dundalk Bay, Ireland. A microplastic range of 1.55 ± 1.38 to 1.92 ± 1.00 g-1 and 3.43 ± 2.47 to 6.90 ± 3.68 ind-1 was reported between seasons. Microfibres dominated the shape of microplastics present in both sediment and cockles. While a wider range of polymers were identified in cockles than in sediment, microplastic concentrations recovered from both intertidal sites studied were approximately double the estimated safe loading levels for this pollutant. The potential of cockles to perform as shallow environment biomonitors of microplastic pollution was identified as they presented buoyant microplastics that were not identified in sediment samples.

Mangrove mud clam as an effective sentinel species for monitoring changes in coastal microplastic pollution

The worldwide mangrove shorelines are experiencing considerable contamination from microplastics (MPs). Finding an effective sentinel species in the mangrove ecosystem is crucial for early warning of ecological and human health risks posed by coastal microplastic pollution. This study collected 186 specimens of the widely distributed mangrove clam (Geloina expansa, Solander, 1786) from 18 stations along the Leizhou Peninsula, the largest mangrove coast in Southern China. This study discovered that mangrove mud clams accumulated a relatively high abundance of MPs (2.96 [1.61 - 6.03] items·g-1) in their soft tissue, wet weight, as compared to previously reported levels in bivalves. MPs abundance is significantly (p < 0.05 or 0.0001) influenced by coastal urban development, aquaculture, and shell size. Furthermore, the aggregated MPs exhibit a significantly high polymer risk index (Level III, H = 353.83). The estimated annual intake risk (EAI) from resident consumption, as calculated via a specific questionnaire survey, was at a moderate level (990 - 2475, items·g -1·Capita -1). However, the EAI based on suggested nutritional standards is very high, reaching 113,990 (79,298 - 148,681), items·g -1·Capita -1. We recommend utilizing the mangrove mud clam as sentinel species for the monitoring of MPs pollution changing across global coastlines.

An overview of microplastics in oysters: Analysis, hazards, and depuration

Microplastic pollution has become an emergent global environmental issue because of its ubiquitous nature and everlasting ecological impacts. In marine ecosystems, microplastics can serve as carriers to absorb various contaminants and the ingestion of microplastics in oysters is of concern because they can induce several adverse effects. The analytical process of microplastics in oysters commonly consists of separation, quantification, and identification. Quantification of microplastics is difficult since information regarding the analytical methods is incoherent, therefore, standard microplastic analytical methods for shellfish should be established in the future. The depuration process can be used to reduce the level of microplastics in oysters to ensure safe consumption of oysters and longer depuration time facilitates improved depuration efficacy. In summary, this review aims to help better understand microplastic pollution in oysters and provide useful suggestions and guidance for future research.

Investigation of Microplastics (≥10 μm) in Meconium by Fourier Transform Infrared Microspectroscopy

Microplastics are prevalent emerging pollutants with widespread distribution in air, land and water. They have been detected in human stool, blood, lungs, and placentas. However, human fetal microplastic exposure remains largely under-studied. To assess fetal microplastic exposure, we investigated microplastics using 16 meconium samples. We used hydrogen peroxide (H₂O₂), nitric acid (HNO₃) and a combination of Fenton's reagent and HNO₃ pretreatment methods respectively to digest the meconium sample. We analyzed 16 pretreated meconium samples with an ultra-depth three-dimensional microscope and Fourier transform infrared microspectroscopy. The result showed that H₂O₂, HNO₃ and Fenton's reagent combined with HNO₃ pretreatment methods could not digest our meconium samples completely. Alternatively, we developed a novel approach with high digestion efficiency using petroleum ether and alcohol (4:1, v/v), HNO₃ and H₂O₂. This pretreatment method had good recovery and non-destructive advantages. We found no microplastics (≥10 μm) in our meconium samples, indicating that microplastic pollution levels in the fetal living environment are miniscule. Different results between previous studies' and ours underscore that comprehensive and strict quality control are necessary for further studies on microplastic exposure using human bio-samples.

Baseline assessment of microplastics in commercially important marine bivalves from New York, U.S.A

Microplastic (MP) contamination in bivalve mollusks has become a significant concern over the last few years. These ecologically and economically valuable species are popular seafood items for human consumption. As filter feeders, bivalves may ingest MPs in their bodies, possibly impacting their physiology and fitness. Additionally, a considerable amount of the seafood that humans consume comes from coastal areas where MP concentrations tend to be the highest. This research provides the first examination of MPs in eastern oysters (Crassostrea virginica) and hard clams (Mercenaria mercenaria) that were grown locally in coastal areas of New York, contributing to a baseline for the northeast and mid-Atlantic regions of the U.S. A total of 48 eastern oysters (n = 12 per site, at four sites) and hard clams (n = 24 per site, at two sites) were sampled in summer 2021. While MP fibers and fragments (i.e. polyethylene terephthalate, polystyrene, and polypropylene) were found in some oysters, other contaminants (e.g. indigo dye, phthalocyanine, dye 823, etc.) were found in both bivalve species. Particle composition was verified using Raman microspectroscopy. Although mean MP concentrations were low in eastern oysters (i.e. 0.008 MPs g^-1 of soft tissue wet weight; 0.125 MPs ind^-1) and not found in hard clams, more research is needed to assess the magnitude of contamination in these edible bivalves.

Microplastic in oysters: A review of global trends and comparison to southern Australia

Microplastics have been documented in a plethora of marine environments and organisms. These small plastics threaten ecosystem health, with implications for seafood species' health. Oysters are an important cultural and economic aquaculture species globally. Due to their filter feeding mechanisms, they can act as an indicator species and proxy for environmental contamination. This makes them an ideal organism for investigating microplastic pollution. Here, we first systematically reviewed the global literature investigating microplastic in oysters. Globally, 94.4% of all oysters had microplastics, with an average of 1.41 ± 0.33 per gram of soft tissue wet weight (gww). The review showed that wild-caught oysters contained more than double the amount of microplastic than aquaculture raised specimens, likely reflecting the clean and productive waters in which oyster aquaculture systems are commonly located. Second, we quantified microplastic presence and polymer type in commercially farmed oysters (Crassostrea gigas and Saccostrea glomerata) across a broad spatial scale, covering eight sites in southern Australia. Microplastics were present in 49.4% of all sampled oysters, with specimens from all locations containing microplastics. On average, whole oysters contained 0.83 ± 0.08 microplastics per individual or 0.09 ± 0.01 microplastics gww. Using Fourier-Transform Infrared Spectroscopy, we identified that 62% of the verified microplastics were vexar plastic netting, a low-density polyethylene commonly used in aquaculture production. Understanding the abundance and source of microplastic in these key seafood species is essential to determine if oysters are vulnerable to these contaminants and pose a risk to the oyster aquaculture industry as an important food resource.