Practice question

Microplastics have been reported in marine and aquatic invertebrates, birds, and whales, among many other organisms. Invertebrates ingest particles during filter feeding, deposit feeding, or grazing; birds acquire them directly and through prey; whales can ingest large numbers while filter feeding or consuming contaminated food. Therefore none of the listed animal groups can be identified as wholly unreported. 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. Because conventional polymers persist, fragmentation redistributes plastic into smaller pieces rather than removing its mass from the ecosystem. Trophic transfer can occur when predators consume contaminated prey, although evidence for consistent biomagnification of particle numbers remains system-dependent.