Marine litter refers to any persistent solid material, manufactured or processed, that is discarded, disposed of, or abandoned in the marine and coastal environment. This global issue affects oceans and coastlines worldwide, highlighting a pressing environmental challenge.
Types and Sources of Marine Litter
Marine litter encompasses a variety of materials, with plastics being the most prevalent type, accounting for approximately 80% of all marine debris. This includes macroplastics, which are larger items such as bottles, bags, and discarded fishing gear, as well as microplastics, tiny particles less than 5 millimeters in size. Microplastics often originate from the fragmentation of larger plastic items or from manufactured microbeads found in certain personal care products. Other common types of marine litter include derelict fishing gear, glass, metals, rubber, and textiles.
The origins of marine litter are broadly categorized into land-based and sea-based sources. Land-based sources contribute the majority, estimated to be around 80% of marine litter, primarily stemming from inadequate waste management, urban runoff, general littering, and industrial discharges. Tourism also plays a role, with waste from recreational activities on coasts and beaches entering the marine environment.
Sea-based sources account for the remaining percentage, including discarded or lost fishing gear, operational waste from shipping activities, and debris from aquaculture and offshore oil and gas platforms.
Impacts on Marine Ecosystems
Marine litter directly harms marine animals through various mechanisms. Entanglement in items like ghost fishing gear or plastic bags can lead to severe injuries, drowning, or starvation by restricting movement and hunting abilities. Ingestion of plastics, often mistaken for food, causes internal injuries, blockages in digestive systems, and a false sense of satiation, leading to starvation. Even small organisms like zooplankton can ingest microplastics, which then move up the food chain, potentially affecting all trophic levels.
Beyond individual animals, marine litter impacts marine habitats. Debris can smother ecosystems such as coral reefs and seagrass beds, disrupting their structure and function. This physical presence can reduce prey acquisition and growth rates for corals and other organisms. Marine litter can also act as rafts, facilitating the long-distance transport of organisms, contributing to the spread of invasive species to new regions.
Human Health and Economic Consequences
The presence of microplastics in the marine environment raises concerns for human health, primarily through the consumption of contaminated seafood. Microplastics can be ingested by fish and shellfish, leading to human exposure. While the long-term effects of ingesting microplastics and associated chemicals are not yet fully understood, studies are ongoing to assess potential toxicity, including oxidative stress, neurotoxic effects, and endocrine disruption.
Marine litter also imposes substantial economic burdens on various sectors. Coastal tourism suffers from reduced aesthetic appeal of beaches, potentially leading to decreased visitor numbers and revenue. The fisheries industry faces costs from damaged fishing gear, reduced catches due to ghost fishing, and contamination of seafood.
Shipping operations incur expenses from propeller entanglement and vessel damage caused by marine debris. Significant financial resources are also expended on beach cleanups and broader waste management efforts. For instance, global annual damages to marine ecosystems from plastic pollution are estimated at $13 billion.
Global Efforts to Combat Marine Litter
Global initiatives to combat marine litter focus on prevention, mitigation, and policy development. Source reduction is a primary strategy, emphasizing efforts to decrease the production and consumption of plastics and other materials that become litter. This is coupled with improvements in waste management infrastructure, including enhanced collection, recycling, and proper disposal systems. Public awareness campaigns also play a role in promoting responsible waste behavior.
Mitigation and cleanup efforts include organized beach cleanups and the development of ocean cleanup technologies designed to remove accumulated debris. Initiatives also target the recovery of derelict fishing gear, often referred to as “ghost gear,” which continues to harm marine life.
Policy and regulatory measures are being implemented at international, national, and local levels. These include international agreements, national laws, and local ordinances aimed at reducing marine litter, such as bans on single-use plastics and regulations concerning fishing gear. The United Nations Environment Assembly, for example, is negotiating a new global instrument to address plastic pollution.