In river mouths flowing into the Mediterranean Sea and Atlantic Ocean, every aquatic species is contaminated with microplastic pollution, according to an alarming new study.
The study was conducted as part of the International Project “i-plastic” led by the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB). Universities in Italy, Portugal, Brazil and Spain have also participated in the project, which was funded by JPI-Oceans.
Microplastics range in size from 5 to 0.0001 mm, and even smaller nanoplastics. They are a significant source of pollution, particularly in estuaries which act as hotspots for their accumulation.
These particles are hazardous as they can capture harmful chemicals and enter the food web, leading to bioaccumulation in higher trophic levels, including commercially valuable species.
The i-plastic team analyzed the presence of micro- and nanoplastics in estuaries and their adjacent coasts.
In addition, 75% of estuarine-dependent marine fishes contained microplastics or synthetic microfibers in their gut. Furthermore, over 85% of species in coastal regions are affected by estuarine outflow, such as European hake and Norwegian lobster.
Nanoplastics, due to their smaller size, pose an even greater risk as they can penetrate cellular membranes.
“Pollution is ubiquitous in estuaries and their adjacent coasts, in the Mediterranean, and in tropical and temperate zones,” said Patrizia Ziveri, an oceanographer at ICTA-UAB and the project coordinator.
She noted that the amount of accumulated particles in sediments has increased in recent decades at the same rate as global plastic production. In addition, since 2000, the particles deposited on the seafloor have tripled. This pollution extends to coral reef systems, causing a reduction in their growth and posing a global threat.
The experts found that areas near urban centers and wastewater treatment plants are particularly polluted with microfibers. This is the most common type of microlitter. When these particles are trapped on the seafloor, they do not degrade due to lack of erosion, oxygen and light.
“Plastics from the 1960s still remain on the seabed, leaving the signature of human pollution,” said Michael Grelaud, oceanographer at ICTA-UAB and coordinator of this project.
Particles that are not deposited on the seabed can be transported by ocean currents and tides hundreds of kilometers in just a few months. “A microplastic from the Ebro estuary in the Northwestern Mediterranean Sea can reach Sicily, in Italy, in six months,” said Ziveri.
The researchers emphasize that bioremediation — the use of living organisms to remove pollutants from water — is one of the few viable options available for reducing microplastic pollution in coastal marine environments.
Laboratory experiments showed that filter-feeder communities could remove nearly 90% of microplastics from surrounding waters. This presents a potentially very effective method to mitigate this environmental crisis.
As discussed above, microplastic pollution, involving tiny plastic particles less than five millimeters in diameter, poses a severe threat to marine life, especially fish.
These plastics come from various sources, such as decomposing larger plastic waste, cosmetic products, and synthetic fibers from clothing. They accumulate in water bodies, creating a significant environmental hazard.
Microplastics make their way into marine ecosystems through runoff water, rivers, and direct ocean dumping. In the ocean, these particles blend with the natural habitat, making them almost indistinguishable from the surrounding environment. Fish, mistaking microplastics for food, consume these particles, leading to direct health consequences.
When fish ingest microplastics, the particles can cause physical blockages and internal injuries. More insidiously, microplastics often carry toxic substances. These include industrial chemicals and pollutants, which can accumulate in the tissues of marine organisms. This accumulation not only affects the health and reproductive capabilities of fish but also poses a risk to predators higher up the food chain, including humans who consume fish.
Recent research has consistently found microplastics in various fish species, both in wild and farmed populations. These studies highlight the pervasiveness of microplastic pollution across different marine environments. Researchers are actively studying the long-term impacts of microplastics on fish health, growth, and reproduction, with initial findings pointing towards various negative outcomes.
Addressing the issue of microplastics in our oceans requires both preventive and corrective measures. Prevention involves reducing overall plastic use, improving recycling, and banning microbeads in consumer products. Corrective measures include cleaning up existing plastic pollution and enhancing wastewater treatment processes to capture microplastics before they reach the ocean.
In summary, the presence of microplastics in fish is a critical environmental issue that requires immediate attention. It calls for a collective effort from individuals, industries, and governments worldwide to reduce plastic pollution and safeguard our marine ecosystems. Consumers can contribute by reducing their plastic footprint and supporting eco-friendly initiatives.
Microplastics in estuaries present a significant environmental concern. Estuaries, being transitional zones between river environments and maritime seas, are crucial ecosystems that often bear the brunt of pollution from both marine and terrestrial sources. The impact of microplastics in estuaries is multifaceted:
Estuaries are rich in biodiversity, hosting various species of fish, birds, and plants. Microplastics can be ingested by marine organisms, leading to physical harm and potential toxicological effects. This ingestion can occur directly or through the food chain, affecting a wide range of organisms.
Microplastics often contain or absorb harmful chemicals. When ingested by aquatic life, these chemicals can bioaccumulate, posing health risks to the organisms and potentially transferring these risks up the food chain, including to humans.
Accumulation of microplastics can alter the physical properties of estuarine habitats, affecting the growth and health of various aquatic plants and animals.
As humans consume seafood from these estuaries, there’s a potential risk of ingesting microplastics and associated chemicals, which can have unknown health implications.
Estuaries provide important ecosystem services such as water filtration, flood control, and as nurseries for fish. The presence of microplastics can compromise these services, affecting both the environment and human populations that depend on these services.
Addressing the microplastics issue in estuaries requires a combination of approaches, including reducing plastic use and waste, improving waste management systems, public education, and conducting further research to understand the full impact of microplastics on these vital ecosystems.
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