The Mediterranean is classified as the sixth highest region on the planet for plastic debris accumulation, with densities of hoarded floating plastics comparable to the ones reported in the five sub-tropical ocean gyres. Plastic debris in the form of microplastics and macroplastics puts at threat this sea of unique biodiversity, which hosts around 10% of world’s marine species, even though it represents less than 1% of the global ocean area. Given the natural and socioeconomic importance of the area, plastic pollution brings serious threats to both marine and human life.
Archipelagos Institute of Marine Conservation initiated its research on the assessment of the extent of the distribution of microplastics in the Greek seas in 2009 with the aim to gain an understanding of the extent of the problem caused by microplastic and macroplastic debris in the Greek seas. The results of this research are actively communicated via the media and targeted campaigns with the aim to share this knowledge with the public and policy makers, but also engage them in actions that combat in various levels the problem of plastic debris.
Archipelagos' partners in microplastic research are:
FIELDS OF ACTION
The aims of our research at Archipelagos are to identify the main
sources of influx of microplastics into the Aegean and quantify the plastic contamination. Another priority of our research is to evaluate to what extent plastic debris and their breakdown products impact the marine ecosystem and its species, including their eventual transfer upstream through the food chain, from plankton to humans.
To these ends the following studies are being undertaken:
1 - Quantifying the microplastic and macroplastic content in the gastrointestinal tracts of stranded dolphins, seals and sea turtles
One of Archipelagos’ key studies focuses on the quantification of microplastic and macroplastic content in the gastrointestinal tracts of marine mammals and sea turtles found stranded on the eastern Aegean coasts. Following dissections, the tissues are processed and the macroplastic content is assessed and quantified. Microplastic fibres and fragments are extracted and identified by microscopic analysis. The results so far are highly alarming, even in the cases where plastic ingestion is not the cause of death. Marine mammals are higher trophic level feeders and therefore their microplastic content is likely to have travelled up the food chain, which is highly pertinent to humans who are also higher level feeders.
2 – Quantifying the microplastic content in the gastrointestinal tracts of different fish species
Research focuses on the quantification of microplastic fibres across a range of fish species from various trophic levels. The main goal of this research area is to provide an indicator of microplastic transfer across the food chain, with possible implications on other marine organisms feeding on these species. Previous studies focusing on pelagic fish species found significantly high concentrations of microplastics in the stomach contents of adult fish (89% of the samples analysed were contaminated). Current research focuses on edible, commercially important fish species which may lead to important findings with possible implications on the health of local consumers.
3 - Quantifying the microplastic gastrointestinal content of selected invertebrates species
Microplastic research is extended to marine invertebrates due to their important ecological role and the lack of studies investigating the plastic content in such organisms. Current research is focusing on the sea urchins, holothurians and bivalves, which are crucially exposed to marine debris and therefore represent important indicators of microplastic contamination.
4 - Quantifying microplastics in surface waters and the water column
Using both kayak-based and boat-based surveys, this research uses a manta net (330μm mesh size) and a plankton net (200μm mesh size) to investigate microplastic concentrations in surface waters and the water column. The manta net is used to collect surface water samples from the boat out in deep waters, while the plankton net is used from kayaks to collect samples in coastal waters. The coastal water samples are collected at the surface and then at intervals of 1m depth, allowing comparisons of microplastic concentrations at different depths down the water column. All samples collected are prepared in the lab and analysed under microscope to identify the microplastics, and to measure the volume contained. This research is carried out in order to assess seasonal and special patterns in microplastic contamination in surface waters.
5 - Quantifying microplastics in marine sediments
Archipelagos Institute started its research on microplastics in 2009 with the analysis of sediments from over 110 beaches throughout Greece, while now this research is ongoing with a current focus on the eastern Aegean area. Results are alarming as several samples from uninhabited islets of the Aegean contained similar concentrations of microplastic fibres, as those from the coasts off Athens. Marine sediments are a good indicator of temporal and special variations in microplastic contamination, as well as of the role of sea currents.
6 - Long-term Macroplastic Monitoring in Remote Beaches
An ongoing survey is carried out to assess the daily load seasonal dynamics of macroplastics in remote beach locations. This data will help to build models of debris aggregation for the broader region of the NE Aegean Sea. After every data collection session, where all debris is analysed and cataloged into data sets to establish a pattern of macroplastics and other debris found, the beaches are cleaned and debris is removed.
Sources of microplastics
The main source of microplastics is as an indirect result of larger plastics thrown into the sea. Exposure to physical and natural processes such as sunlight, waves and wind causes the plastic debris to be broken down into smaller particles. Direct sources include products such as face and body scrubs, shampoos, deodorants, sun-screens etc. These can contain plastic microparticles made of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA) and nylon. Another threat which is recently getting more attention is synthetic clothing; an average washing machine load (6kg) with acrylic fabrics can release more than 728 000 fibres into the sewage system.
A large volume of the microplastics and their sources mentioned above pass through wastewater treatment plants. However, their elimination is not possible with current sewage treatment technology, therefore whether the water is processed or not, all microplastics present may end up in water ways.
What Happens When Microplastics Enter the Environment?
Small pieces of plastic or fibres have been found in all marine organisms, including important commercial species of fish, mussels and crabs, many of which enter in the human food chain. The number of discovered affected organisms is expected to grow exponentially, given that until today the relevant research has been focused on only a small percentage of species. Plastics contain toxic substances themselves (flame retardants, antioxidants, softening agents etc.) and are also able to adsorb and accumulate other toxic substances found in seawater (like polychlorinated biphenyl and dichlorodiphenyltrichloroethane – PCB and DDT, respectively). In areas of intense industrial activity, unsurprisingly these levels are much higher compared to other areas. It is likely that due to their durability these small plastic particles will remain in the water for hundreds of years.
The Myth of Degradable Plastic
The development of so called “bio-degradable plastics” ,also termed oxo-plastics, for food-packaging, compost and carrier bags seems to be a step in the right direction toward the avoidance of polluting plastics. However, as these oxo-plastics are still commonly fossil-based (e.g. PE, PP, PET) and use chemical additives to catalyse their degradation, their labelling as bioplastics is debatable. According to the EU Directive 94/62/EC (more specifically EN 13432) bio-degradable plastics are supposed to break down into CO2, water and minerals to at least 90% within 6 months by biological action. However, until now there has been no reliable study which proves the full degradation of oxo-plastics into organic matter within a reasonable timeframe. Therefore, it remains important for nations to establish policies to control and regulate the use and consumption of oxo-plastics as well as conventional plastics. Greece however - in contrast to other countries – has as yet to establish such policies.
How long does it really take to degrade Plastic?
Plastics vary in composition and strength and break down over different timeframes. Harsh environmental conditions accelerate the decomposition process and break plastics into smaller pieces. However it is these small pieces which will remain in the environment for hundreds of years and thus cause harm to organisms in numerous ways.