The first ever assessment of litter in the deepest place of the Mediterranean, located in the Hellenic Trench in Greece’s eastern Ionian Sea, has found one of the highest concentrations of deep-sea litter ever detected, raising grave concerns about ocean pollution and the conservation of marine habitats due to human activity.
The floor of the deepest site in the Mediterranean Sea known as Calypso Deep or as Oinousses Deep, has a depth of 5,122 meters and is 60 kilometers west from the closest shoreline in Greece’s Peloponnese near Pylos. At its bottom, researchers discovered plastic, glass, metal and paper waste -with plastic accounting for almost 90 percent of the litter material.
“The litter abundance in the Calypso Deep, with 26,715 items per square kilometer is one among the highest ever recorded in a deep-sea environment,” the study, which has been published in the journal Marine Pollution Bulletin, notes. According to the study, the calculated litter concentration is the second highest known to date in the deep ocean (deeper than 2,000 meters).
Scientists estimate that seas and oceans produce over 70 percent of the oxygen needed on Earth. Today, the survival of the oceans and their delicate ecosystems hangs in the balance because of climate change, pollution (especially from plastics and chemicals) and other human activities that also directly threaten human life.
Researchers analyzed data collected by an advanced crewed submarine called the Limiting Factor and concluded that “the deep sea is often a final sink for pollution” and that it is dominated by plastic items because they “are lightweight and very easy to transport by marine currents.” Most litter arrives to the Calypso Deep as sea surface floating debris.
“Some light waste, such as plastics, comes from the coast, from where it escapes to the Calypso Deep. Some plastics, such as bags, drift just above the bottom until they are partially or completely buried or disintegrate into smaller fragments,” Dr. Miquel Canals, one of the authors of the study explains. “We have also found evidence of boats dumping bags full of rubbish.”
In some places of the trench, the researchers even found different types of interaction between the debris and marine organisms. For example, they found instances of animals ingesting the debris and using it as a substrate to grow, hide or lay their eggs.
The Mediterranean is an enclosed sea and since the trench is a “closed depression” with weak currents, it favors the accumulation of debris. “Unfortunately, as far as the Mediterranean is concerned, it would not be wrong to say that ‘not a single inch of it is clean,’” Dr. Canals says.
He further adds that the Mediterranean is “surrounded by humanity, with intense maritime traffic and widespread fishing activity. The evidence provided by our research should shake up global efforts, and in particular in the Mediterranean, to mitigate waste dumping, especially plastics.”
Greece’s imposing, clear-blue beaches that are enjoyed by millions of visitors every summer are drowning in trash and plastic with the situation across the Mediterranean being no better, a new report has found.
The report, published by the World Wildlife Fund (WWF) on March 6, paints a bleak picture on the pollution that’s taking a hold of Greece’s beaches. From data collected across 192 beaches in the country between 2021 and 2024, none fulfills the minimum threshold of 20 pieces of trash for every 100 meters of coast to be considered clean, according to the relevant European directive. Instead, WWF’s study detected an average of 464 pieces of trash for every 100 meters of coast, a number that’s multiple times above the minimum requirements. In total, 298,000 pieces of trash were collected for every 100 meters of coast in the 192 beaches studied between 2021 and 2024.
What makes the report’s findings even more worrisome is that the vast majority of trash found (83 percent) is plastic, with cigarette butts holding the top spot, followed by plastic caps, plastic bottles, plastic bags, pieces of styrofoam and others.
WWF further notes that half of all trash objects collected from Greece’s beaches between 2021 and 2024 comprise of only five objects: cigarette butts (25 percent), small pieces of plastic (between 2.5 and 50 centimeters), plastic caps, straws and pieces of styrofoam.
Plastic pollution is one of the most serious environmental problems of the modern world, with serious consequences for biodiversity, human health and the economy. Plastic waste breaks down into microplastics, which pose an unseen risk as microscopic plastic particles enter the food chain through marine life, resulting in impacts on human health.
WWF’s report is part of a “citizen science” program, which in Greece began in 2021 and is called “Adopt a Beach.” The program has so far mobilized 173 teams of volunteers across the country, who are trained by WWF staff in the detection and registration of trash in the 192 beaches they have so far “adopted.”
The program has been expanded to Turkey, Tunisia and Italy and offers a clearer picture on the scale of the problem across the Mediterranean, where 338 beaches were studied between 2023 and 2024 and the findings are just as discouraging. Data showed that 83 percent of the pollution is due to the presence of plastics, with glass, metal and paper following in much smaller concentrations.
