Microplastics are found throughout the ocean and in the bodies of marine animals from zooplankton to whales. Their effects on individual animal welfare are increasingly documented.
Microplastic ingestion causes welfare harm through multiple mechanisms. Physical blockage of digestive systems by larger plastic fragments impairs digestion and can cause intestinal perforation. False satiety from stomach full of indigestible plastic reduces food intake, causing malnutrition in seabirds and turtles. Chemical toxicity from plastic additives and accumulated persistent organic pollutants causes hormonal disruption affecting reproduction and development. Behavioral changes in fish exposed to nanoplastics include altered predator avoidance and reduced shoaling behavior - changes that increase individual predation risk. The pervasive and growing nature of marine plastic pollution means that virtually all marine animals are exposed to some level of microplastic throughout their lives, making it a chronic welfare challenge of global scale.