Microplastics contaminate all marine species in river mouths

All the aquatic species of the mouths of the rivers of the Mediterranean Sea and of Atlantic Ocean are contaminated by microplasticsand mollusks are the most affected due to their ability to filter the water.

It is the conclusion of the international i-plastic project, in which the Spanish Institute of Environmental Science and Technology of the Autonomous University of Barcelona (ICTA-UAB) participates, which analyzed the presence of micro and nanoplastics in estuaries and adjacent coasts. .

Rivers are one of the main sources of microplastic (5 to 0.0001 mm in size) and nanoplastic (less than 0.0001 mm) pollution in the oceans.

The concentration of microplastics is especially high near urban centers along rivers and the outlets of wastewater treatment plants, which are the main source of microfiber pollution.

This is the most common type of microwaste in estuaries, transition zones between rivers and the sea that are important sources of accumulation of these particles, which are retained in the sediments.

Microplastics pose a threat to aquatic ecosystems due to their ability to capture harmful chemicals from the environment, enter the food chain through ingestion and bioaccumulate towards higher trophic levels within the food chain.

The conclusions of the project indicate that, of the bivalve species analyzed (mollusks), the 85% of mussels and 53% of the oysters had ingested microplastics.

Estuarine marine fish (white mullet, silver crappie, and Brazilian crappie) were affected in a 75%while, in the coastal areas close to the mouths, the 86% of European hake and 85% of Norwegian lobster contained microplastics.

Scientists explain that contamination by nanoplastics can be even more problematic than by microplastics, since they can cross the cell membrane and damage organisms to a greater extent.

“Pollution is omnipresent in estuaries and adjacent coasts, both in Mediterranean, tropical and temperate zones”warned the ICTA-UAB oceanographer and project coordinator, Patrizia Ziveri.

According to the specialist, the amount of particles accumulated in the sediment has increased in recent decades at the same rate as the global production of plastics, and since 2000 the particles deposited on the seabed have tripled.

When they reach the seabed, the particles do not degrade due to lack of erosion, oxygen and light.

“Plastics from the 1960s still remain at the bottom of the sea, leaving traces of human pollution,” explained ICTA-UAB oceanographer Michael Grelaud, another of the coordinators of this project subsidized by JPI-Oceans, in which universities from Italy, Portugal, Brazil and Spain have participated.

Particles that do not settle on the seabed can be transported by currents and tides hundreds of kilometers in a few months.

The researchers emphasize that bioremediation, which consists of the use of living organisms to eliminate contaminants from water, is one of the few viable options to reduce pollution in coastal marine environments.

In laboratory experiments, different species of filter-feeding communities eliminated almost the 90% of microplastics from surrounding waters.