Marine and coastal pollution, caused mainly by human activities, is one of the major threats to marine ecosystems.

On average, there are 450 million people living in the Mediterranean, and it is estimated that by 2025 this number will have risen to 520 million, of which 150 million will be concentrated along or close to the coastline. Moreover, the Mediterranean is a popular tourist destination attracting approximately 200 million visitors annually. In addition to this vast influx of visitors, the Mediterranean hosts unique ecosystems of plants and animals and it is known as a biodiversity hot spot.  

The Mediterranean is the most waste polluted sea in Europe according to studies1Senet, S., 2019, Mediterranean is Europe’s most waste-polluted sea study says. The millions of tons of waste that find their way into the sea each year result in seriously injuring or killing marine species and polluting their natural environment.  Marine pollution is a global threat for living marine organisms.

>260 species ingest plastic debris, monofilament line, rubber and aluminum foil.
The problem particularly affects fishes, cetaceans and marine turtles, animals in whose digestive tracts, accidentally ingested micro and macro plastic debris are commonly found.
The Barcelona Convention, signed by 22 Mediterranean Countries, underlines the need to control the marine pollution to reduce the risk for Mediterranean biodiversity.

 The Marine Strategy Framework Directive considers marine litter one of the most serious pollutants of the sea, stating that the Good Environmental Status of the Mediterranean Sea would be reached only when “properties and quantities of marine litter do not cause harm to the coastal and marine environment”2Marine and coastal environment (europa.eu).

Poor practices of solid waste management, waste water (including storm water) collection and treatment, lack of infrastructure and awareness of the public about the consequences of their actions and daily habits aggravate substantially the situation3https://ec.europa.eu/, Our Oceans, Seas and Coasts, Descriptor 10: Marine Litter))

Moreover, the Mediterranean Sea is one of the busiest seas in the world, accounting for 20% of seaborne trade, 10% of world container throughput and over 200 million passengers6. The increased traffic also increases the possibility of maritime accidents, while routine ship operation discharges is a permanent pressure.

On the other hand, there is a growing interest and attention to the problem of marine pollution the last years. The growing number of NGOs addressing the problem of marine litter, the increasing media coverage and the spread of information, have made it practically impossible to hide the reality. Τhus regional and international institutions like the European Union and the United Nations have placed it in the forefront.

Marine Litter Definition

According to the United Nations Environment Programme (UNEP), “marine litter is defined as any persistent, manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment. Marine litter consists of items that have been made or used by people and deliberately discarded into the sea or rivers or on beaches; brought indirectly to the sea with rivers, sewage, storm water or winds; accidentally lost, including material lost at sea in bad weather (fishing gear, cargo); or deliberately left by people on beaches and shores4UNEP, 2009. Marine Litter: A Global Challenge. Nairobi: UNEP. 232 pp.

The European Commission expanded the above definition by including in the category of marine litter “semi-solid remains of for example mineral and vegetable oils, paraffin and chemicals that sometime litter sea and shores5MSFD Task Group 10 report, European Commission/JRC/Ifremer/ICES 2010

Global Impact

Marine litter is a global issue that has an enormous environmental and economic impact, while also presenting a significant threat to human health and aesthetics. Litter and all sorts of rubbish are being dumped into the seas and oceans as an inexpensive method of disposal, even today. We come across cigarette butts, plastic and other kinds of litter even in the most remote corners of the earth, thousands of miles away from areas of human habitation. It is estimated that 80% of all marine litter originates from land-based sources while 20% of it is the result of human activities at sea.

The complex issue of marine litter has its roots in the inefficient management of solid waste, the lack of suitable infrastructure, the failure to adopt effective legislation and the lack of control mechanisms and financial resources. Going hand in hand with this the significant lack of understanding when it comes to the consequences of our actions and attitudes is an aggravating factor.

Threat to marine species

As the Mediterranean is a semi-enclosed sea, marine litter poses a very serious threat to the Mediterranean basin. Connected to the Atlantic Ocean by the Strait of Gibraltar its waters are only renewed approximately once every 100 years!

Each year turtles, birds and other marine animals die unnecessarily after swallowing marine litter, especially plastic due to their shape,size and smell. Specifically, sea turtles mistake the plastic bags that end up in the sea for their favorite delicacy, the jelly-fish. Furthermore, in a recent study conducted by Pfaller et al. (2020), it was found that plastics can even smell like food to loggerheads. Biofouling organisms and algae attach themselves to plastic and expel odorants into the surrounding environment; these odours mislead the turtles into thinking the plastic is actually a food source6Pfaller J.B., Goforth K.M., Gil M.A., Savoca M.S. & Lohmann K.J. (2020), Odors from marine plastic debris elicit foraging behaviour in sea turtles, Current Biology 30(5). Plastics ingestion by sea turtles may cause them to suffocate, block their digestive tract and make them feel full though in reality they may be starving to death! Furthermore, air bubbles in plastics consumed can prevent turtles from diving for food.

Turtles and Marine Pollution

Marine litter, including abandoned and derelict fishing gear, may either cause injuries to marine organisms or lead to their entanglement. This either prevents them from swimming or makes them more vulnerable to their predators. Litter on nesting beaches becomes a deadly trap to hatchlings. The tiny baby turtles are prevented from reaching the sea quickly, making them easy prey to their natural predators such as seabirds and crabs that lurk on the beach waiting for a tasty morsel. Moreover, if hatchlings are trapped on the beach until sunrise instead of making it straight to the sea, may become dehydrated in the heat and perish.

Over time, plastic breaks down into smaller particles also known as microplastics. All plastics contain several toxic substances acquired either during their production or during their time at sea.


The microfibers released during the washing of synthetic clothes and the microplastics (aka microbeads) contained in personal care and cosmetics products (PCCPs), like scrubs and peeling creams, shower gels, toothpastes etc., pass through washing machine and sewage treatment plant filters and end up in the marine environment. In many habitats throughout the world microplastics are more abundant than any other man-made material and can pollute not only water but also food and the air.

Microplastics are building up in the marine environment in significant quantities, and we still have only a limited understanding of the effect of this. Because of their small size, their ingestion by fish and other animals near the top of the food chain is highly probable. We can speculate as to the consequences for the health of the marine creatures that end up on our plates!

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