The microplastics in the marine environment are described and reported since 1970 . However, Thompson in 2000 was the one who first coined the descriptive term for these, the same that denominated as those particles or fragments of plastics < to 5 millimeters of diameter. Since then, research in the world has increased significantly, predominantly in controlled aquaculture and laboratory. The most recent studies of microplastics have conducted in fish, water, and sediment.
Nowadays, it is possible to observe contamination by plastics in practically all the oceans of the world; this includes the most remote areas known to humans.
The objective of the present study was to examine the presence of microplastics in the digestive tracts of the most commercialized marine fishes species for human consumption in the northwestern part of the Mexican Pacific.
Four quarterly samples were carried out, during an annual cycle, obtaining a total of 720 organisms of six different species, captured using artisanal fishing techniques. Also, were examined some samples of water and sediment from the caught area.
In the laboratory, the intestines of the caught fishes were analyzed, applying 30% hydrogen peroxide (H2O2) to disintegrate the organic matter. Residues filtered on cellulose paper (Whatman number 40), then the filter was dried at 50 ° C and the microplastics identified. In the case of water and sediment samples, an adaptation of the technique described above made, adding zinc chloride (ρ = 1.5 g / l) as an extra reagent to obtain particles through buoyancy.
Of the six species of fish analyzed, three of them presented contamination by microplastics . The size of these contaminants varied from 0.33 mm to 4.8 mm in diameter. The most frequently found microplastics were Nylon fragments, followed by pieces of plastic bags (polyethylene) and particles derived from PET containers. The present study shows a relationship between the types of microplastics in marine fish's intestines and those plastics observed in sediment. For this reason, it suggested that; Sediment contamination is a risk factor for the health of the ichthyofauna present in the studied area.
Keywords: Microplastics, Marine fishes, water, sediment.