Practice question

Plastic ingestion affects marine birds, mammals, turtles, and fish, as well as many invertebrates. Animals may mistake fragments for prey or ingest particles indirectly through contaminated food. Consequences include gut blockage, false satiation, reduced body condition, tissue injury, and exposure to additives or sorbed contaminants. Restricting the effect to one group ignores extensive observations across trophic levels and feeding modes. Trophic transfer can occur when predators consume contaminated prey, although evidence for consistent biomagnification of particle numbers remains system-dependent. Standardised sampling and contamination controls are essential because airborne fibres can enter samples during collection and laboratory processing. Particle size, shape, polymer type, weathering state, and associated chemicals all influence uptake and biological response, so microplastics are not a uniform toxicant. Laboratory effects must be interpreted alongside environmentally realistic concentrations, while field detection demonstrates exposure but does not alone prove causation. Prevention requires reducing unnecessary plastic use, improving collection and recycling, controlling lost fishing gear, and limiting releases of fibres and tyre-wear particles.