From Ocean to Plate: The Invisible Tide of Microplastics in Bivalves

Consider the humble mussel clinging to a pier piling. It is a living pump. Every hour, it draws in litres of seawater, sieving out plankton to fuel its growth. It is a quiet, rhythmic process that has sustained these creatures for millions of years. But today, the water carries a ghost. The mussel cannot distinguish between a nutrient-rich alga and a microscopic shard of polypropylene. It swallows both.

This is the scene set by a new review of 56 studies published between 2016 and 2024. Researchers examined the global state of contamination, and the results paint a stark portrait of human influence on the marine environment. The ocean is washing our rubbish back onto our dinner plates.

Tracking microplastics in bivalves

The review aggregates data from experimental studies and biomonitoring efforts to map exactly what these animals are consuming. The findings are specific and unsettling. While one might imagine jagged chunks of broken bottles, the data shows that fibres are the dominant intruder. These are the shed remnants of synthetic clothing and fishing gear, drifting through the water column like invisible webs.

Polystyrene and polypropylene appeared as the most frequently reported polymers. In terms of aesthetics, black and white particles were the most common colours found within the tissues. The load of plastics varied wildy depending on geography, acting as a mirror to local human activity. Where there is fishing, there are nets. Where there are cities, there are textiles.

The study establishes bivalves as highly effective bioindicators. Because they do not migrate and filter vast quantities of water, their bodies record the history of local pollution levels with high fidelity. While the review measures the presence of these particles, it also suggests a darker implication for food security. As humans consume the entire soft tissue of these animals, we may be stepping into the same contaminated loop, turning a biological necessity into a toxicological gamble.