Microplastics uptake and egestion dynamics in Pacific oysters, Magallana gigas (Thunberg, 1793), under controlled conditions

Abstract

Microplastics debris (<5 mm) are increasingly abundant in the marine environment, therefore, potentially becoming a growing threat for different marine organisms. Through aquatic animals, these can enter in the human food chain, and can be perceived as a risk for consumers' health. Different studies report the presence of particles in marketable shellfish including the world wide commercially grown Pacific oyster Magallana gigas (Thunberg, 1793). The aim of this study is to examine the potential risk of microplastics entering in the human food chain through this shellfish species, investigating the dynamics of the uptake, egestion (faeces) and rejection (pseudofaeces) of microplastics in Pacific oysters under controlled conditions. M. gigas collected from a farm in the San Teodoro lagoon (Italy), were exposed to 60 fluorescent orange polystyrene particles L-1 of known sizes (100, 250 and 500 µm). The uptake of each particle size was 19.4 ± 1.1%, 19.4 ± 2 % and 12.9 ± 2 % respectively. After exposure M. gigas were left to depurate for 72 hrs, during which 84.6 ± 2 % of the particles taken up were released whilst 15.4 ± 2 % were retained inside the shell cavity. No microplastic particles were found in the animals' soft tissues. The results of this study, suggest that depuration is an effective method to reduce presence of large microplastic particles, in the size range 100 to 500 µm, in M. gigas. Importantly, the data suggests that the burden that could theoretically be up taken by consumers from these shellfish is negligible when compared to other routes. Capsule Microplastic of tested sizes were not retained in the tissues but can be retained in the shell cavity; Depuration is an effective method to reduce microplastics in farmed Pacific oysters

Bioaccumulation and biomagnification of microplastics in marine organisms: A review and meta-analysis of current data

“…Such studies would also provide critical information for more realistic and comparative laboratory studies, including environmentally relevant exposure characteristics such as concentrations, polymer type, and plastic size, shape and colour, a recommendation raised in previous reviews [ 95 – 97 ]. Many of these characteristics have been demonstrated to affect retention, and thus bioaccumulation of MPs [ 64 , 98 , 99 ], but have rarely been examined using environmentally relevant exposures. Currently, comparisons between exposure and uptake of MPs and chemical additives in controlled laboratory studies are further complicated by the absence of measured versus nominal concentrations [ 16 , 100 ].…”

Microplastics in Mollusks: Research Progress, Current Contamination Status, Analysis Approaches, and Future Perspectives

“…Microplastics can be transferred to the hemolymph, muscle, and other tissues or organs through phagocytosis (Scanes et al, 2019). Many of them are identified by bivalves as foreign elements then are removed (Birnstiel et al, 2019;Graham et al, 2019). It is suggested that MPs that reach the digestive tract are packaged into fecal particles and eliminated, but some of them will remain in the digestive tract (Fernández and Albentosa, 2019b), which are likely to affect the gut microbiota and damage internal organs (for example, hepatopancreas).…”

Ingestion of microplastics by free-living marine nematodes, especially <i>Enoplolaimus</i> spp., in Mallipo Beach, South Korea

“…Some studies have been conducted on the egestion of microplastics by macroorganisms. For example, Graham et al (2019) showed that pacific oysters have efficient egestion rates of microplastics (84.6±2%) and Van Cauwenberghe et al (2015a), who analyzed the fecal casts of Polychaeta, showed that they excrete some microplastic particles.…”