Littering is the improper disposal of man-made waste, which poses a significant threat to global biodiversity. This waste, including plastic bottles and discarded fishing gear, infiltrates virtually every ecosystem, from the deepest ocean trenches to remote terrestrial habitats. As a non-biodegradable contaminant, litter persists, polluting soil and water and harming the wildlife that interacts with it.
External Physical Hazards: Entanglement and Restriction
Discarded materials pose an immediate physical danger to wildlife through entanglement and restriction. Plastic items like six-pack rings can easily become restrictive collars around the necks or bodies of animals. As juveniles grow, these constricting bands do not expand, leading to deep, painful lacerations, severe infections, and sometimes complete severing of tissue or limbs.
“Ghost gear,” including abandoned fishing nets, lines, and traps, is particularly devastating in marine environments. These durable materials continue to trap and ensnare sea turtles, seals, cetaceans, and seabirds, leading to drowning or slow starvation because the animal’s mobility is severely limited. On land, items like rubber bands or plastic ties can wrap around the beaks of birds or the limbs of small mammals, preventing them from foraging for food or escaping predators.
Ingestion, Blockage, and Internal Poisoning
When animals mistake litter for food, the consequences move from external injury to internal system failure. Marine animals, such as sea turtles, frequently ingest plastic bags because their appearance mimics jellyfish, a natural prey item. Once consumed, this indigestible material occupies space in the stomach and intestines, creating a false sense of satiety that leads to chronic malnutrition and eventual starvation.
Internal blockage is compounded by the risk of puncture from sharp or rigid plastics and metals, causing internal bleeding or severe infections. Furthermore, plastics act like sponges, absorbing persistent organic pollutants (POPs) from the surrounding environment, such as polychlorinated biphenyls (PCBs) and the pesticide DDT. When an animal ingests plastic, these toxins can leach into the digestive tract and tissues, leading to bioaccumulation that can impair reproductive function, disrupt endocrine systems, and compromise immune defenses.
The breakdown of larger plastic items into microplastics—particles less than five millimeters in size—introduces this threat lower down the food chain. Filter-feeding organisms and small prey animals consume these tiny particles, which are then passed up to predators in a process of trophic transfer. The toxic load from plastic can thus affect species at all levels of the ecosystem, including those that never directly interact with macro-litter.
Chemical Contamination and Habitat Alteration
Beyond direct physical harm, litter alters the chemical and physical characteristics of natural habitats. Items like discarded batteries and electronics leach heavy metals, such as cadmium and lead, into soil and water sources. Similarly, plastics release compounds like endocrine disruptors and flame retardants as they degrade, changing the chemical composition of the environment. These chemical changes are particularly harmful to aquatic life, such as amphibians, which have highly permeable skin and are susceptible to waterborne pollutants.
Large accumulations of litter, such as illegal dumping sites, physically alter the landscape and disrupt established ecological patterns. These sites can obstruct natural migration routes and become artificial attractors for certain species, like rodents and insects, which thrive on discarded food waste. The presence of these species can introduce new pathogens and create imbalances in the local food web, putting pressure on indigenous wildlife.