Marine litter is defined as “any persistent, manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment”. From derelict fishing gear to cosmetic microbeads, its various forms and sizes are found from pole to pole near coastal shores to the depths of the oceans. Larger pieces can accumulate on beaches or at the ocean floor but are also a threat to marine life through entanglement and shocking. Plastics of any size fragment into smaller pieces under various processes such as the influence of UV and mechanical stress. Microplastics are now widely distributed through the oceans and they can be vectors for pollutants and pathogens. The behaviour and impact of smaller size plastic pieces is under investigation. Most polymers manufactured today is likely to persist for decades and probably for centuries, if not millennial.
In addition to polymers, additives such as flame retardants, and plasticizers are mixed into synthetic materials to increase their flexibility, transparency, durability, and longevity. Some of these substances are persistent organic pollutants (POPs) listed under the Stockholm Convention on Persistent Organic Pollutants. In 2019, the Conference of the Parties to the Basel Convention adopted a set of actions for reducing the generation of plastic waste, improving its management, controlling its movement, reducing the risk from hazardous and raising public awareness, education, and information exchange.
Marine litter is a multi-dimensional problem with economic, environmental, cultural, and human health costs. To address this issue, the United Nations created Sustainable Development Goal (SDG) 14, “Life Below Water” and Target 14.1: “by 2025, prevent and significantly reduce marine pollution of all kinds, from land-based activities, including marine debris and nutrient pollution”. To achieve this target, there is a need to identify marine litter and assess marine litter observation and detection methods to inform policy. A variety of international and regional instruments and approaches exist to protect biodiversity, manage hazardous chemicals and wastes, and monitor and prevent pollution of the marine environment from ocean-based and land-based sources of pollution. The cooperation among those initiatives and activities is key to effectively addressing this global environmental challenge.