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On the beaches of Canary Islands, sand grains… but also micro-plastics

Canary Islands are not devoid of pollution by plastics. But the location of the most polluted beaches shows that micro-plastics do not originate from the important local touristic activity but are transported by marine currents.

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In spite of the obvious improvements in societal awareness and regulations at the national and international levels, plastics continue to be produced, consumed and discarded at an increasing rate, with many consequences for the biosphere, particularly in the marine environment. Several questions remain to be answered about the origin of this pollution, its magnitude in the world's ocean and the coastal zones, its consequences for biosphere and the possible solutions to the problem.

Within a research project initiated in 2008, a study dealt with one of the components of the problem (micro-plastics), a coastal region (the Canary Islands) and a societal approach (creating dialogue between local stakeholders and the scientific community). The first step was to evaluate the magnitude of the problem, identify the most vulnerable sites, and establish baseline data for future actions.

The three studied islands (Lanzarote, La Graciosa, Fuerteventura) share the same volcanic shelf and contain many well preserved and protected natural areas, including on the littoral. They are relatively rural but they experience a tremendous influx of tourists, more the one million per year, i.e. nearly five times more than their resident population. In spite of the protections rules, the shoreline is subjected to pollution by plastics.

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Example of a sample of micro-plastics contained into one liter of sediment

Micro-plastics are defined here as pieces not larger than 5 mm. The objective of the study was to quantify their abundance on the whole shoreline of the islands, whose sandy beaches (125) were all sampled; rocky shores were not covered as micro-plastics cannot deposit there because of the high energy of wave breaking. A total of 194 sand samples were collected along the high tide mark between 10 and 26 January 2013. The debris found here were deposited during a single tide cycle. On the contrary, those found on the last spring tide mark and even farther onshore on the storm line were accumulated during more than one tidal cycle: these lines were therefore not sampled. The sampling consisted in collecting the surface layer of sand (1 cm thick) within a 50 cm square centered on the high tide line, i.e. a volume of one liter. Micro-plastics were separated from sand grains by flotation in water, then dried, weighed and saved for further analysis; their abundance is expressed in grams per liter of sediment

On Fuerteventura as on the other islands, observations showed that he vulnerability of sandy beaches to pollution by micro-plastics depends on their orientation to winds, currents and waves, but also on the sand area remaining at high tide; when the beach is uncovered only at low tide, there is little or no space available at high tide for micro-plastics to deposit.

The highest concentration observed in Fuerteventura is 30 g/l. All high concentrations were found on the western shores of the island; on the contrary, all beaches of the eastern coast (where hotels and touristic activity are concentrated) have only very low concentrations, not exceeding 1 g/l. On Lanzarote and la Graciosa, concentrations higher than 100 g/l were found on some beaches; the southern coast of Lanzarote –here again the most populated- is globally the least affected..

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Micro-plastics concentration on the sandy beaches of the three islands

Generally speaking, the highest concentrations were found on the beaches whose orientation is north to north-east.

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Micro-plastics concentration on the 125 beaches according to their orientation

These results show that the majority of micro-plastics observed on Canary Islands beaches are not of local origin. They are mainly provided by surface currents, and are most often produced by the degradation and fragmentation of plastics pieces of larger size (macro-plastics) whose origin can be related to illegal discards from the active and increasing maritime traffic in the region, or to waste disposal on nearby or remote coasts.

Canary Islands are located on the eastern edge of one of the five regions where wind-driven surface currents cause the convergence of marine debris. The most heavily polluted beaches found in this study are directly exposed to these currents. The fact that micro-plastics cannot deposit on the beaches submerged at high tide does not mean that they are absent from the water column: it is thus the whole study area which is affected by this kind of pollution.

This situation has multiple consequences. Not only can their ingestion be harmful to organisms, but micro-plastics transport on their surface contaminants (heavy metals and other compounds) and pathogen micro-organisms, which is a serious threat for areas like the Canary Islands, where the aquaculture of potentially high value species is growing. In addition, recent studies have shown that the chemical degradation of plastics can generate toxic substances.

The working group guiding this research launched a social campaign called "Plastic 0: Agüita con el Plástico" targeting citizens, schools and coastal communities. Efforts are also underway to improve the coordination of social agents, governmental administrations, civil society, and other stakeholders. Another output of this work was to establish a standard sampling methodology that could be used elsewhere and by stakeholders and institutions with limited resources and expertise.


The paper

Baztan J., Carrasco A., Chouinard O., Cleaud M., Gabaldon J.E., Huck T., Jaffrès L., Jorgensen B., Miguelez A., Paillard C., Vanderlinden J.-P., 2014. Protected areas in the Atlantic facing the hazards of micro-plastic pollution: First diagnosis of three islands in the Canary Current. Marine Pollution Bulletin 80(1–2) : 302-311.

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The authors

The authors of this paper work in several laboratories in France (IUEM/Lemar, IUEM/LPO, Observatoire de Versailles Saint-Quentin-en-Yvelines), Spain (Observatorio Reserva de Biosfera, Dynamical Systems), Canada (Université de Moncton), USA (University of Maine), but also in other structures, associative (Marine Science for Society, Barcelone) or artistic (Le Théâtre du Grain, Brest). This research is part of a project coordinated by Marine Sciences For Society and the Observatorio Reserva de Biosfera in Lanzarote.


The journal

Marine Pollution Bulletin is an international journal aimed at scientists, engineers, administrators, politicians and lawyers concerned with the rational use of resources in estuaries, the seas and oceans, as well as with marine pollution. A wide range of topics are discussed as news, comment, reviews and research reports, not only on effluent disposal and pollution control, but also on the management, economic aspects and protection of the marine environment in general.



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