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 thresholds

Microplastics are particles smaller than 5 mm (millimetres) in their longest dimension; macroplastics are items of 5 mm and above. Smaller items have higher surface-to-volume ratios, weather faster, sorb chemicals more readily, and can pass through feeding structures; larger items dominate entanglement and physical obstruction.

Material families

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 and products

Forms indicate how items behave. Films (bags, wraps) crumple and tear into long strips; fibres (lines, ropes, nets) wear down and release microfibres; foams (EPS) break into small beads; pellets (pre-production) are small, smooth spheres; rigid items (caps, crates) crack along stress lines. Each form has typical hotspots and exposure routes. For example, films and foams strand in wrack lines after storms; fibres lodge in filters and gills; rigid fragments accumulate near ports and busy marinas. A form-aware survey records what is seen (form), not only where and when.

Why classification matters

Size guides action, together with material and form.

• Microplastics (<5 mm): fragments, fibres and pellets. High surface area speeds weathering and chemical sorption; they can pass through filters and feeding structures. Priority: upstream control and interception along coastal areas.
• Macroplastics (≥5 mm): bags, bottles, rigid fragments and gear parts. They drive entanglement and physical obstruction. Priority: recovery in the sea (Fishing for Litter) and targeted seabed operations, then conferimento to certified cooperatives for sorting, recycling 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 is a tool, not an end. Recovery in Ogyre is a priority. Each haul is weighed, geo-referenced and delivered to certified cooperatives for sorting, recycling, or responsible disposal, always prioritizing the most sustainable outcome. Every lot is registered on blockchain to guarantee 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 actionable planning for the circular economy.

• FAO (2021), Seabed Sources of Marine Litter link
• European Environment Agency – EEA (2020), Plastics, the Circular Economy and Europe’s Environment – A Priority for Action 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

👉 How big is global plastic waste today? link

👉 How does mismanagement fuel marine pollution? link

👉 How does plastic enter the Ocean? link

👉 What is marine litter made of? link

👉 Floating vs. seabed plastic: which is worse? link