Microplastics (<5 mm) and macroplastics (≥5 mm) behave differently in marine environments. Clear size, material and form classes guide recovery and reporting.

Plastic in marine environments is not a single category. It fragments, floats, sinks, and travels across currents and coastal areas. A practical classification clarifies exposure and impact: size (micro vs macro), material (polymer families), and form (film, fibre, pellet, foam, rigid). These classes determine behaviour because buoyancy, fragility, and surface area control transport and interactions with organisms. Therefore, a consistent taxonomy improves both monitoring and prevention across the entire chain—from interception along coastlines to recovery in the sea.

Size

Microplastics are particles smaller than 5 mm (millimetres) in their longest dimension; macroplastics are items measuring 5 mm and above. Size is a primary driver of environmental behaviour and biological impact. Smaller particles expose more surface area relative to their size. This means they break down faster, more easily pick up chemicals from the surrounding environment, and can be swallowed by organisms that filter water or feed on tiny particles. Larger items, by contrast, cause harm mainly through physical contact, leading to entanglement, scraping, and blockages that interfere with movement and basic biological functions in organisms and habitats.

Material

Polymers differ in density, rigidity, and weathering patterns. Polyethylene and polypropylene (common in packaging and fishing gear) are typically buoyant in seawater and accumulate at the surface or strand along coastal areas. PET, PVC, and PA (nylon) are denser and, once marine life grows on them, they often sink or move up and down in the water. These properties guide collection: floating items can be intercepted by surface fishing nets or coastal clean-ups; heavier items require seabed operations and diver-assisted retrieval.

Forms

Form determines how plastic items move, break down, and interact with the environment. Films (bags, wraps) tend to crumple and tear into long strips; fibres (lines, ropes, nets) gradually wear down and release microfibres; foams (EPS, expanded polystyrene used in packaging) break into many small beads; pellets (pre-production resin) are small, smooth granules that abrade slowly, generating progressively smaller fragments; rigid items (caps, crates, containers) crack at edges, corners, and previously stressed areas, producing hard, angular pieces.

Each form is linked to characteristic hotspots and exposure pathways. After storms, films and foams strand along the wrack line and in seagrass meadows; fibres tend to lodge in filters, nets, and gills; rigid fragments accumulate in areas of intense human activity, such as ports and busy marinas.

Recording form means documenting what is actually observed—the type of object and how it appears—rather than only where and when it is found. This makes monitoring more informative and improves interpretation of the underlying processes.

Why classification matters

Size, together with material and form, determines how plastic behaves in marine environments and which responses are most effective.

• Microplastics (<5 mm) include fragments, fibres, and pellets. Their small size gives them a large exposed surface, which accelerates weathering and chemical uptake and allows them to pass through filters and feeding structures of many organisms. Because they are difficult to remove once dispersed, the priority is upstream control and interception along coastal areas, before they enter the sea.
• Macroplastics (≥5 mm) include bags, bottles, rigid fragments, and parts of fishing gear. Their impacts are mainly physical, driving entanglement and obstruction of organisms and habitats. Here, the most effective actions are direct recovery in the sea through Fishing for Litter activities and targeted seabed operations, followed by delivery to certified cooperatives for sorting, recycling where possible, or responsible disposal.

Effective mitigation occurs where waste meets water. Ogyre acts in the sea—recovering debris encountered by fishers during regular outings according to the Fishing for Litter model—and along coastal areas, intercepting ocean-bound waste in estuaries, ports, and crowded beaches before it reaches marine environments. This dual approach connects offshore accumulation zones with on-shore inputs.

Classification guides decisions, but impact is delivered through operations. Ogyre acts both in the sea and along coastal areas. Marine litter encountered during regular fishing activities is recovered by local fishers, while ocean‑bound waste is intercepted in estuaries, ports, and crowded beaches before it reaches marine environments.

Recovery is the priority. Each catch is weighed, geo‑referenced, and delivered to certified cooperatives for sorting, recycling when possible, or responsible disposal, always aiming for the most sustainable outcome. Every batch is recorded on blockchain to ensure traceability and data integrity. This end‑to‑end chain keeps results auditable and comparable, supports risk ranking and transparent reporting, and turns recovery data into operational insight for circular‑economy planning.

• European Environment Agency – EEA (2020), Plastics, the Circular Economy and Europe’s Environment – A Priority for Action link
• FAO (2021), Seabed Sources of Marine Litter link
• OECD (2022), Global Plastics Outlook link
• United Nations Environment Programme – UNEP (2021), From Pollution to Solution: A Global Assessment of Marine Litter and Plastic Pollution link
• United Nations Environment Programme – UNEP (2024), Global Waste Management Outlook 2024 link
• WWF (2022), Impacts of Plastic Pollution in the Oceans on Marine Species, Biodiversity and Ecosystems link
• WWF (2020), Stop Ghost Gear. The Most Deadly Form of Marine Plastic Debris link