Uncovering microplastics contamination in canned seafood.

There is limited research on the occurrence of microplastics (MPs) in canned seafood. All types of canned seafood investigated in the present study were contaminated. After sample digestion in 30 % hydrogen peroxide, a total of 40 MPs were recovered. Fibers were the most common type, blue was the dominant colour, and Fourier Transform Infrared Spectroscopy (FTIR) identified polyester as the most common polymer. Considering all samples, an average of 3.5 ± 5.2 MPs/can was obtained, with octopus in tomato sauce and tuna in olive oil presenting the highest contamination (5.2 ± 7.5 MPs/can and 5.2 ± 5.1 MPs/can, respectively). Also, significant differences between the number of MPs in the seafood tissues and immersion liquids were verified. The present study demonstrates MPs occurrence in canned seafood, a potential contamination pathway for humans. More research on the different stages of the canning processing is vital for understanding MPs contamination in cans.

Microplastic contamination in large migratory fishes collected in the open Atlantic Ocean.

Fishes are one of the most important components of the oceans and are exposed to several anthropogenic pressures, namely microplastic (MP), contaminants that are now ubiquitous worldwide. Taking advantage of the 2020 Circumnavigation Expedition carried by the NRP Sagres tall ship of the Portuguese Navy, fish samples from the southern Atlantic ocean were collected to evaluate possible MP contamination. In a total of 14 weeks of campaign, seven large migratory fishes of commercial interest were collected across the middle Atlantic Ocean and along the South American Atlantic coast. All individuals were contaminated with MPs, with an average of 18 ± 11 MPs/fish. In all fish sampled, both the gastrointestinal tract and gills presented MPs, indicating different contamination pathways including via their preys and from surrounding water, respectively. A total of 124 MPs were observed, where 72 % were fibers and 28 % particles, mostly of blue color (85 %), and with rayon and nylon as the most abundant polymers. This study is an important contribution to increase the scientific knowledge of MP contamination in mesopelagic fishes used for human consumption and collected in the open waters, reinforcing the need for further research regarding MP contamination in top predatory species from high trophic levels.

Optimization of an Analytical Protocol for the Extraction of Microplastics from Seafood Samples with Different Levels of Fat.

Marine organisms are affected by the ubiquitous occurrence of microplastics (MPs) in the environment. Several protocols have been described to extract and quantify MPs in seafood, although their complex matrices, with high level of fat, can compromise the efficiency of MPs extraction. To solve this issue, the present study aimed to develop a detailed methodology suitable to process seafood samples with different levels of fat, namely fish and molluscs, from fresh and canned sources, including the immersive liquids from the cans. Sample digestion was tested using different solutions (10% KOH, 30% H2O2), temperatures (40 °C, 65 °C) and incubation times (24, 48, 72 h). For fat removal, three detergents (two laboratory surfactants and a commercial dish detergent) and 96% ethanol were tested, as well as the manual separation of fat. The methodology optimized in this study combined a digestion with 30% H2O2 at 65 °C, during 24 to 48 h, with a manual separation of the fat remaining after the digestion. All steps from the present methodology were tested in six types of polymers (PE-LD, PET, PE, AC, PS, and lycra), to investigate if these procedures altered the integrity of MPs. Results showed that the optimized methodology will allow for the efficient processing of complex seafood samples with different fat levels, without compromising MPs integrity (recoveries rate higher than 89% for all the polymers tested).

Microplastics and plankton: Knowledge from laboratory and field studies to distinguish contamination from pollution.

Due to their ubiquitous presence, size and characteristics as ability to adsorb pollutants, microplastics are hypothesized as causing a major impact on smaller organisms, such as plankton. Despite this, there is a need to determine whether these impacts just relate to the environmental presence of the materials or their effects on biological processes. Therefore, we aimed to 1) review current research on plankton and microplastics; 2) compare field and laboratory experimental findings, and 3) identify knowledge gaps. The systematic review showed that 70% of the 147 relevant scientific publications were from laboratory studies and microplastics interactions with plankton were recorded in 88 taxa. Field study publications were relatively scarce and the characteristics of microplastics collected in the field were very different from those used in laboratory experiments thereby limiting the comparison between studies. Our systematic review highlighted knowledge gaps in: 1) the number of field studies; 2) the non-comparability between laboratory and field conditions, and 3) the low diversity of plankton species studied. Furthermore, this review indicated that while there are many studies on contamination by microplastics, the effects of this contamination (i.e., pollution per se) have been less well-studied, especially in the field at population, community, and ecosystem levels.