Microplastic pollution in seawater and marine organisms across the Tropical Eastern Pacific and Galápagos

Abstract

Detection of plastic debris degrading into micro particles across all oceanic environments and inside of marine organisms is no longer surprising news. Microplastic contamination now appears as one of the world's environmental main concerns. To determine the levels of microplastic pollution at sea, water samples were collected across a 4000 km-trajectory in the Tropical Eastern Pacific and the Galápagos archipelago, covering an area of 453,000 square kilometres. Furthermore, 240 specimens of 16 different species of fish, squid, and shrimp, all of human consumption, were collected along the continental coast. Microplastic particles were found in 100% of the water samples and marine organisms. Microplastic particles ranging from 150 to 500 µm in size were the most predominant. This is one of the first reports simultaneously detecting and quantifying microplastic particles abundance and their impact on marine organisms of this region.

Figure 1

Spatial interpolation of the microplastic particle concentrations in the study area. Using the known values of microplastic particles concentrations determined (µp/m³), combining both 150 and 500 µm-plankton nets at the precise oceanic stations, estimate concentration values are determined at the remaining unknown spatial points. The Southeast and Northwest presented the lowest microplastics concentration, which was coloured in blue. The highest microplastic concentration was observed in international waters in the central to southern part of the study area coloured in red, potentially associated with ocean circulation patterns.

Figure 2

Microplastic fibres and particles under the microscope. Each of the filters collected was inspected and investigated under the microscope to quantify the amount of microplastic fibres and particles. Most polymers, the main structural molecular blocks of plastics, tend to shine under the ultraviolet light (UV-light), which was done using a BX53 Olympus microscope.

Figure 3

Prevalence of microplastic particles in the digestive track of marine species. Microplastic particles found in 16 different marine species of human consumption that were bought in the most representative ports in all four provinces (Manabí, El Oro, Esmeraldas and Santa Elena) in the Pacific coast of Ecuador were quantified. Marine organisms were categorized by their feeding behaviour: carnivorous, planktivory, and detritivore. Fifteen specimens (n = 15) were taken per each of the 16 species analysed.