Plastic waste pollution in the world’s seas has become a major environmental problem, one from which the Mediterranean is sadly not immune. The geography of the Mediterranean as a closed area, connected with the North Atlantic only by the Strait of Gibraltar, gives it one of the highest densities of plastics in the world—250 billion micro-plastics.
Even though it has received less attention than the infamous “garbage patches” that form in major oceans, the Mediterranean remains then one of the regions most threatened by marine litter. The plastic waste is threatening the region’s wildlife, with reports of whales dying after consuming plastic bags and tuna found with stomachs full of cellophane.
A 2015 article in PLOS journal found that the average density of plastic was at least comparable to the great garbage patches within the five subtropical ocean gyres where plastics have accumulated. As in the gyres in the open ocean, the authors noted, the majority of the plastic on the surface waters of the Mediterranean was comprised in the main by millimetre-sized fragments. The difference in this instance however was a higher proportion of larger-sized fragments, a fact the authors felt reflected the proximity of the smaller sea, almost entirely surrounded by land, to the sources of pollution.
The authors of the PLOS study found that the cumulative weight of the floating plastic in the Mediterranean Sea was between roughly 1,000 and 3,000 tonnes. They speculated that this unusual density was likely a combination of the high population density on the coast around it, and the particular nature of the hydrodynamics of what in the Mediterranean is essentially semi-enclosed basin—outflow from which mainly tends to take place though through a deep-water layer, which clearly would not carry plastics floating on the surface out into the open sea.
From the Atlantic, for example, the Strait of Gibraltar created a kind of ‘convective basin’ from the Atlantic, ‘light Atlantic’ water flowing inward over the ‘denser, deeper outflow’ from the Mediterranean water, and inevitably trapping the floating plastics within its semi-enclosed basin structure. While noting that no proper estimates had been made for the exact volumes of the plastics entering it, the PLOS study pointed out that the Danube was ‘conservatively estimated’ to be depositing 1,533 tons of plastic into the Black Sea each year—a figure they speculated the Nile alone could well be matching into the Mediterranean.
Given the biological richness and concentration of economic activities in the Mediterranean Sea, the PLOS study anticipated that the destructive effects of plastic pollution on marine life would be particularly severe—findings corroborated by the WWF study mentioned above. As the head of marine policy at the WWF, Lyndsey Dodds, told The Independent, the levels of microplastics in the Mediterranean she and her research team had found were nearly four times those in the North Pacific ‘plastic island.’ The net effect of its geography and the amount of plastic find its way into it thanks to the population pressures around it meant that, while the Mediterranean holds only 1 per cent of the world’s water, it contains 7 per cent of all of the world’s microplastic waste.
Another related study in the same journal in 2016 found that the ratio of plastic to plankton, the basis of the marine food chain, reached particularly high values in the surface waters of the Mediterranean close to the coast—again reflecting the pivotal significance of population pressure on the sea as an influencing factor in the problem of plastic pollution. The 2016 study found that polyethylene, polypropylene and polyamides were the predominant plastic polymers at all distances from the coast, constituting 86 to 97% of all items they found. They did note a higher diversity of polymers in the 1-kilometre strip of surface water adjacent to the coast, attributing this to a higher frequency of polyacrylic fibers. We can only conclude that these came from synthetic fabrics worn by people in and around it.
The particular features of the problems associated with plastic pollution in the Mediterranean render unmistakable the problems associated with single-use plastic production in its traditional form. While it might be easier to ignore plastic pollution out in the open ocean, the proximity of the Mediterranean to large human populations in Africa, Asia and Europe brings the consequences of reckless consumerism and the tendency to treat the planet as an infinite resource home where we can see them. It shows once more the urgent need, amongst other things, to abandon single-use plastics, and to produce commodities using environmentally friendly materials such as bamboo and coconut which will break down and can be absorbed back into the ecosystem.
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