Perspectives on the impact of microplastics (MPs) on fish of the Amazon that exhibit air-breathing and aquatic surface respiration.

Fish in the Amazon basin have adapted to bouts of low water O2 and high CO2, with many species evolving air-breathing or aquatic surface respiration mechanisms to supplement respiratory gas exchange. While concurrently coping with greater instances of hypoxic and hypercarbic stress, fish in the Amazon are also facing microplastic pollution. Assessments of the Amazon basin reveal some of the highest microplastic concentrations globally. In this article, we highlight instances in which the evolution of air-breathing and aquatic surface respiration may make fish of the Amazon particularly susceptible to the effects of microplastic pollution. We consider these effects as they relate to gill morphology, specialized air-breathing organs, ion transport processes, aquatic surface respiration, and oxidative stress. Finally, we relate our perspectives with the recently published Executive Summary of the Status of Water Quality in the Amazon Basin to highlight the importance of considering microplastics alongside other pollutants threatening the ecological, economical, and cultural values of the Amazon.