Marine litter

Marine litter is any persistent material, manufactured or processed by humans, that ends up deposited, directly or indirectly, in the marine environment or on its shores.

Although plastic attracts most media and scientific attention, marine litter also frequently includes metals, glass, cigarette butts, synthetic textiles, treated wood and even hazardous items such as batteries.

Main sources of marine litter

Litter reaches the sea through many pathways, the most important being:

• Urban and domestic discharges: insufficiently treated wastewater, rubbish dumped in rivers and canals, and items washed away by storms.
• Coastal and tourism activities: beaches, ports and recreational areas, especially during the high season.
• Fishing and maritime transport: intentional or accidental loss of nets, gear and all kinds of plastic and metal items (ghost nets, ropes, packaging, drums, buoys).
• Rainwater and river run-off: floods and storms that drag waste from cities and industrial estates down to river mouths.

According to the United Nations Environment Programme (UNEP), more than 11 million tonnes of plastic enter the ocean every year (estimates range roughly from 8 to 12 million tonnes), and when all aquatic ecosystems are considered the figure is higher still. This causes serious ecological damage.

Types of marine litter

Although the diversity is enormous, the most notable categories are:

• Plastics: bags, bottles, packaging, microplastics and textile-fibre fragments.
• Metals: cans, tools and fragments of vessels.
• Glass: remains of containers, glasses and bottles.
• Cigarette butts: one of the most common items on urban beaches.
• Hazardous waste: batteries, oils and medical material.
• Synthetic textiles and rubber: nets, boat tarpaulins and tyres.

Microplastics deserve special attention: fragments smaller than 5 mm coming from the breakdown of larger plastics or from cosmetic and textile products.

Environmental, economic and social impacts

Impact on ecosystems

Thousands of species of fish, birds, turtles and marine mammals are harmed in various ways:

• Accidental ingestion causing digestive blockages and death.
• Entanglement in nets and objects that hampers movement and feeding.
• Damage to sensitive habitats: coral reefs, seagrass meadows and nesting areas.

Economic consequences

Tourism suffers from the deterioration of beaches and coastal areas, reducing visitor numbers and generating clean-up costs. Fishing is affected by the contamination of fishing grounds and even by the presence of microplastics in commercial products.

Risks to human health

The indirect ingestion of microplastics and associated toxins (phthalates, adhered pesticides) through the food chain represents a potential health risk that is still under investigation.

Legislation and regulatory action

In Spain, Law 7/2022 on waste and contaminated land for a circular economy, together with the EU Single-Use Plastics Directive (Directive (EU) 2019/904), impose strict restrictions on the dumping and marketing of packaging and potentially polluting products. Coastal municipalities have stepped up monitoring and environmental-education campaigns.

Prevention and mitigation strategies

Prevention at source

• Reducing the consumption of non-reusable plastics.
• Designing biodegradable and reusable packaging.
• Putting in place separate-collection systems and tackling littering.

Clean-up and recovery of coastal environments

• Volunteer brigades for beach clean-ups.
• Underwater clean-ups by specialised divers.
• Installation of barriers at river mouths.

Education and awareness

Environmental groups and public authorities run regular campaigns to raise awareness of the impact of litter on marine wildlife and the importance of separating and collecting all kinds of waste properly.

Innovation and circular economy

Recovering marine litter through advanced recycling is a growing avenue, closely linked to waste prevention and the circular economy. Some textile companies already develop garments from fibres recycled from plastics collected at sea.

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