Microplastic contamination in the gills of Macrobrachium amazonicum (Heller, 1862) from the reservoir of the Funil Hydroelectric Power Plant, Minas Gerais, Brazil

This study aimed to assess the presence of microplastics (MPs) in the gills of Macrobrachium amazonicum shrimp, identifying the most abundant categories (type, shape, degradation level, and color), and testing if there is a significant difference in the mean number of MPs among demographic classes, size classes, and collection months. Shrimps were collected between August 2021 and March 2022 from the Funil Hydroelectric Power Plant reservoir in Minas Gerais, Brazil. Each specimen was sexed, measured, and had its gills dissected. MPs were visually identified, categorized, and counted under a microscope. A total of 4,808 MPs were obtained with the most abundant microplastic being fiber, elongated, degraded, and transparent. Juveniles had the lowest mean number of MPs, being significantly different from the others (p-value = 1.289e-08). Results from the size classes supported these findings, as smaller individuals had a lower average of MPs. Temporal analysis showed variation throughout the months: November and December had the lowest contamination levels, while February had the highest. These findings suggest potential temporal fluctuations in environmental MP exposure. The observed patterns may have long-term implications, as MP accumulation could affect the health of M. amazonicum, a species of significant ecological and economic importance.