Practice question

Plastic debris can carry microbial biofilms, including potential coral pathogens, and transport them to new hosts or hold them against wounded tissue. Entanglement and abrasion create lesions that facilitate infection, while shading and hypoxia weaken coral defences. This combination can raise disease risk through pathogen hitchhiking. Plastics do not generally sterilise reefs; bleaching may occur under stress but is not the specific mechanism described here. 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.