All aquatic species inhabiting river mouths flowing into the Mediterranean Sea and Atlantic Ocean are contaminated with microplastic, according to a recent study. The study, in which the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB) plays a key role, exposes the severity of pollution in estuaries and coastal regions, particularly affecting molluscs.
ESTUARIES AS HOTSPOTS OF POLLUTION: A DISTURBING REALITY
Estuaries, acting as transition zones from rivers to the sea, emerge as major hotspots for microplastic accumulation, threatening aquatic ecosystems. The study finds that rivers, significant contributors to oceanic microplastic pollution, transfer these particles to estuaries, where they accumulate in sediments. The ability of microplastics to capture harmful chemicals, enter the food web, and bioaccumulate poses a substantial threat to marine life.
SPECIES UNDER SIEGE: MOLLUSCS BEAR THE BRUNT
Among the bivalve species analyzed, a staggering 85% of mussels and 53% of oysters revealed ingestion of microplastics. Estuarine-dependent marine fishes, including white mullet, silver mojarra, and Brazilian mojarra, displayed a 75% prevalence of microplastics. Coastal regions influenced by estuarine outflow witnessed 86% of European hake and 85% of Norwegian lobster containing microplastics or synthetic microfibers in their gut.
NANOPLASTICS: AN EVEN GRAVER THREAT
The study emphasizes the potential seriousness of nanoplastic pollution, posing a greater risk to aquatic organisms. Nanoplastics can penetrate cellular membranes and harm species living in estuarine and marine environments more profoundly. Mussels, in particular, were found to be significantly affected by nanoplastic pollution.
GLOBAL AND PERVASIVE THREAT: IMPACT ON CORAL REEFS
The pollution extends globally, impacting coral reef systems across depths. The amount of accumulated microplastic particles in sediments has surged in recent decades, parallel to global plastic production. Urban centers and wastewater treatment plant outflows, major contributors to pollution, discharge microfibers into estuaries, exacerbating the crisis.
TIMELESS POLLUTION SIGNATURE: PLASTICS FROM THE PAST
The study underscores the persistent nature of plastic pollution, with particles from the 1960s still present on the seabed, leaving an enduring signature of human-induced pollution. Lack of erosion, oxygen, and light in the seafloor preserves these particles, emphasizing the long-lasting impact of plastic pollution.
TRANSPORT ACROSS OCEANS: A SWIFT MENACE
Microplastic particles not deposited on the seabed pose a transoceanic threat, transported by ocean currents and tides over hundreds of kilometers in just a few months. The study reveals that a microplastic from the Ebro estuary in the Northwestern Mediterranean Sea can reach Sicily in Italy within six months.
BIOREMEDIATION: A VIABLE SOLUTION
The researchers advocate for bioremediation, utilizing living organisms to remove pollutants from water, as a viable option to address microplastic pollution in coastal marine environments. Laboratory experiments demonstrated that different species of filter-feeder communities effectively removed almost 90% of microplastics from surrounding waters.
As the menace of microplastic pollution unfolds in rivers and estuaries, urgent measures are needed to mitigate the impact on aquatic ecosystems and protect marine life.