Intraspecific and temporal variation in potential microplastic ingestion by Macrobrachium amazonicum (Heller, 1862) in the Funil Hydroelectric reservoir, Minas Gerais, Brazil

Microplastic (MP) pollution is an increasing concern in freshwater environments, where these microparticles are easily ingested by aquatic organisms. This study aimed to investigate intraspecific variation in potential microplastic (PMPs) ingestion by Macrobrachium amazonicum, considering factors such as sex, size, and seasonal changes. Shrimp samples were collected from the Funil Hydroelectric reservoir (Minas Gerais, Brazil) between April 2021 and March 2022. For every individual, the sex and cephalothorax length (CT) were recorded, and the stomachs were subsequently removed. Stomach contents were analyzed under a microscope to identify and quantify PMPs. Overall, 1,214 PMPs were observed in the stomachs of 308 shrimps and occurred in individuals of all sexes, size classes and months of the year. The females ingested a significantly higher amount of PMP than the males, possibly linked to different habitat occupation patterns. PMP consumption increased with shrimp size, suggesting dietary shifts throughout growth stages. Seasonal variations in PMP ingestion were also observed, likely associated with drought and rainfall conditions. December showed the lowest PMP intake, whereas October had the highest. We conclude that PMPs are consumed across shrimp life stages and persist in their habitat throughout the year, highlighting the ongoing spread of this pollution in freshwater environments.