A new study in the journal PLOS ONE has revealed the extent to which the Mediterranean is becoming filled with discarded plastic, with plastic density estimates as high as one item per 4m2. The study concludes that the total amount of floating plastic could be as high as 3,000 tons.
The sampling process took place in twenty-eight sites across the Mediterranean, including the waters of Spain, France, Italy, Greece, and Cyprus.
These results also confirmed that the Mediterranean has one of the highest concentrations of plastic in the world, with only the north and south gyres (rotating ocean currents) of the Atlantic Ocean containing a larger area of floating plastic. The next highest concentrations can be found in the gyres of the Indian and Pacific Oceans.
‘Plastic concentrations in the Mediterranean are comparable to those found in the five subtropical gyres,’ says Andrés Cózar from the University of Cádiz, Puerto Real, Spain, and lead author of the study. ‘We still know little about other marginal seas, such as the China Sea, Red Sea, North Sea. But now we know that the Mediterranean shows one of the highest levels of plastic pollution in the world.’
The study suggests that the Mediterranean’s high concentration of plastics could be a result of, firstly, the high population around the Sea, discarding plastic items directly into the Mediterranean. While noting that there have been no proper estimates for the exact volumes of this plastic, the study points out that the Danube is ‘conservatively estimated’ to be depositing 1,533 tons of plastic into the Black Sea each year, a figure which the Nile alone could well be matching into the Mediterranean.
A second source could be from the Atlantic, where ‘light Atlantic water’ flows over the ‘denser, deeper outflow of Mediterranean water’ through the Strait of Gibraltar, resulting in the Mediterranean acting as a ‘convective basin’ for the Atlantic.
The Mediterranean Sea represents less than one per cent of the global ocean area, but is home to between four and 18 per cent of all marine species. Fishing industry, aquaculture, maritime transport and coastal tourism are all key sources of income for the Mediterranean nations, all of which could be significantly impacted by the growing problems associated with marine plastic pollution.