Les déchets solides en mer et sur le littoral

• Macrodebrises consist of persistent solid materials of human origin, transformed or manufactured, lost, discarded or deliberately abandoned in nature and ending up in the aquatic environment. They are made of plastic, wood, metal, glass, rubber, textile or paper. • More than 10 million tonnes of macrodebrises are released into the marine environment each year. The bulk, 80%, comes from land and the rest, 20%, from maritime activities: shipping, fishing, aquaculture. These waste affect all compartments of the marine environment. It is estimated that 15% have been deposited on beaches, the most obvious sign of this pollution, 15% float on the surface or in the water column and the majority, 70%, has sunk and settled on the seabed. • Starting from a pollution initially considered as an aesthetic nuisance, studies have demonstrated numerous potentially harmful effects on the marine environment, such as the transport of persistent organic pollutants, the diffusion of toxic compounds, the spread of exotic species, the entanglement of large organisms (mammals, fish), mortality of numerous marine species (seabirds, turtles) and changes in the structure of benthic communities (living near the seabed). • The sources of waste in the sea are diverse: • Domestic, agricultural and industrial activities; • Fishing and shellfish farming; • Major recreational boating sectors; • Landfills; • Maritime transport (passing ships, ports ...);

• The quantity and nature of waste remains poorly understood on the French coast despite collection and sorting initiatives launched by public authorities and non-profit organizations; awareness of their impacts is meanwhile increasing. • Data on macrodebrises on beaches are by far the most abundant and oldest. These waste are indeed the most visible and accessible for observations. Existing information results from studies conducted by scientific teams using various methods (Velander and Mocogni, 1999, Loubersac, 1982) as well as by numerous organizations. The importance of data collected on beaches compared to other compartments also reflects the recent evolution of this issue, long considered a visual and aesthetic nuisance and now regarded as genuine marine pollution with multiple impacts. • These waste originate from terrestrial and maritime activities. They can also be abandoned directly by beach users, particularly in summer, or come from inputs by sea or wind. Plastics represent approximately 80% of waste counted on the coast. Others—sanitary waste, paper and cardboard, fabric, metal and glass—represent much smaller shares. Food packaging is well represented. Hygiene and health-related waste is also present. Biofiltering media (culture substrates for microorganisms used to purify wastewater) from treatment plants also wash up on beaches in non-negligible quantities depending on the area. Children's toys, bait boxes and fishing line are also found, indicating leisure activities. Finally, the tobacco sector—with countless cigarette butts, cigarette packs, lighters and plastic packaging films—is also present. • Types of waste counted on coastlines

• There are few assessments of floating waste. Given the immensity of surface areas to cover for reliable estimates, these observations are often conducted by scientific teams during multi-objective oceanographic surveys (cetacean and seabird counts, surface plankton sampling, etc.). There are also some observation initiatives by navigators during ocean crossings and circumnavigations (e.g., Watch the Waste). • Methods for observing and counting macrodebrises on the seabed are generally implemented by scientific teams with oceanographic resources or in partnership with professional fishermen, which ensures methodological rigor and result reliability (Galgani et al, 2000; Stefatos et al, 1999). On European seabeds, plastics, some of which are buoyant, represent more than 70% of observed waste. A significant quantity of fishing gear is also found on the bottom.

• Approximately three-quarters of waste observed on coastlines, floating on the surface and deposited on the seabed are plastic, which does not decompose but breaks into particles transported by currents. Studies have shown that some plastics are already in microplastic form when they reach the marine environment. This is the case with industrial pellets, raw materials for making plastic objects. • Microplastics are defined by their size between 0.3 and 5 mm. The only available data in France concern an assessment of industrial microplastics (granules) on beaches near urbanized areas on all coasts, as well as a survey of floating microparticles in the Mediterranean and the Bay of Biscay.

• Waste sources are numerous in the Channel-North Sea. The sub-region experiences very dense maritime traffic due to major ports from the Seine estuary to Antwerp, Hamburg and Rotterdam. Fishing and shellfish farming are also very active. This area has several large cities (Dunkirk, Calais, Boulogne, Rouen-Le Havre) with relatively limited tourism compared to the Bay of Biscay and Mediterranean coast. There are also two industrial zones in the Pas-de-Calais (Boulogne–Calais–Dunkirk) and in the Seine estuary (Rouen–Le Havre). Finally, two major rivers flow there: the Seine and, with much lower flow, the Somme. • On the coast, waste accumulates near the mouths of the Somme and Seine in areas varying according to river flow. The Seine's contribution is far from negligible with deposits on beaches estimated at 9,000 tonnes over 30 years. Intense maritime traffic and strong fishing activity also generate waste inputs consisting mostly of plastics, although a small percentage remains waste abandoned on site. Tidal currents are significant in the Channel and have a strong impact on waste distribution along the coast. Finally, mussel farming can also be a source of macrodebrises, potentially accounting for up to 60% of waste in the Somme (mussel bags), according to the Conservatoire du littoral. • At sea, it is difficult to estimate floating waste due to currents in this area and analytical difficulties. Monitoring in the northern zone (North Sea entrance) would help clarify quantities entering the North Sea, a source of transboundary issues. Similarly, a one-time assessment and evaluation of Seine inputs would provide currently unavailable information. • On the bottom, data from IBTS (International Bottom Trawl Survey) campaigns, particularly in the Eastern Channel, will track quantity changes to achieve Good Ecological Status under the Marine Strategy Framework Directive (MSFD). • The only available data on microparticles in this sub-region concern industrial microplastics (floating stranded granules, polystyrene spherules excluded) on beaches near natural, urbanized or industrial areas. Seine Bay is the only Eastern Channel zone where high concentrations of industrial plastic granules have been recorded (Le Havre marina). This pollution mainly comes from port and industrial basins and Seine inputs. In the Eastern Channel, a particle concentration containing approximately 50% of 'recycled granules' is found on certain natural beaches in the Strait of Calais, which could come from the Seine and Somme estuaries via northeastward currents in this area. In Cotentin and North Brittany, the presence of granules is sporadic and probably linked to strong dispersion.

• The area is characterized by physical constraints, notably regarding currents, the absence of deep zones and low tourism pressure, limited to islands. Essential factors consist of significant fishing activity, surrounding waste sources, and a shipping lane with considerable traffic, approximately 150 ships per day. • Ushant is the only land in this marine sub-region and no data exists on macrodebrises on its coast. • At sea, according to IFREMER survey data, nearly 90% of waste in this area comes from fishing. There are also risks of sporadic or even accidental waste inputs from ships (such as container loss).

• Several rivers flow into the bay. On the French side, the main ones are the Loire, Garonne, Charente and Adour. Prevailing winds are from the west. Maritime transport is limited to transit to major ports (Nantes, Bordeaux and La Rochelle) and continent-islands transit. • Tourism is developed along the entire coast and recreational boating activity is strong in summer. Fishing activity is localized on the shelf and upper continental slope, particularly in South Brittany and the Basque country. The Portugal Current (Northern Spain) brings waste, mainly to the Basque country and the Landes. Finally, shellfish farming is developed particularly in Arcachon, Marennes-Oléron, Bourgneuf Bay and South Brittany. • This sub-region shows high variability in waste distribution on the coast. Certain waste types are well represented (biofiltering media from treatment plants, cotton swabs). Aquitaine coasts are heavily affected by macrodebrises, particularly in the Landes and Pyrénées-Atlantiques (52 m³/km of beach/year of non-natural waste collected). • Trawling data reveal higher waste concentrations at sea near the Loire estuary and in a wider offshore zone extending southward, likely due to strong fishing activity south of Brittany. Other significant areas are the mudflat off the Gironde, due to westerly swells and high Garonne flows in winter, and the two South Atlantic canyons, particularly Capbreton, where waste tends to accumulate (Galgani et al., 2000). • Regarding sea microplastics, a survey in May 2013 revealed an average of 318 particles/ha across 25 samples. Beach data are partial and focus mainly on industrial granules (synthetic plastic polymers before shaping and industrial use) and show larger quantities on Aquitaine beaches.

• The continental Mediterranean coast is densely populated with some of the largest metropolitan cities like Marseille, Toulon, Cannes and Nice. It also has significant tourist capacity and water sports are prevalent. Maritime traffic is dense and currents are strong (Liguro-Provençal current from Italy flowing along the coasts). The seabed is cut by numerous canyons, especially off Provence but also Roussillon. Finally, wind is often strong, particularly from the northwest (Mistral and Tramontane) and the Rhône has the highest flow of any mainland river (average 1,700 m³/s). • Beach waste sources are diverse and depend on the season. In summer, heavy beach and mooring area use leads to increased waste from bathing activities. Year-round, chronically or exceptionally depending on weather, waste results from the combination of several phenomena: individual discharges scattered in coastal cities and more or less appropriate street and watercourse management, swept by natural elements, rain and wind carrying them to sea. Macrodebrises washing up on the French Mediterranean coast are predominantly plastic (90%). • Although it is still difficult today to observe a trend given available data, collected quantities are not declining. Main accumulation zones are located downwind and near river mouths. Islands, exposed to all winds and located off densely populated and tourist areas, constitute ideal study sites. From 1987 to 2011, the average anthropogenic waste on daily-cleaned beaches is 0.08 m³/100 m. On a preferred stranding zone (La Crine beach on Frioul) rarely maintained (mechanical screening or manual cleaning), studied from 2007 to 2011, the volume per cleaning is 6.44 m³/100 m. • Data from international demersal trawling campaigns (near the bottom) in the Mediterranean (MEDITS) show significant floating waste off Toulon, Cannes and Nice, with the Marseille area remaining less affected. Little floating waste is present near coasts and abundance increases offshore. This floating waste distribution on the surface, variable over time, is mainly conditioned by marine currents, particularly the Liguro-Provençal current, and very locally by winds. In Corsica, floating waste is more uniformly distributed, though with higher densities off the Ajaccio Gulf. • Data for assessing seabed waste in western Mediterranean were acquired during trawling campaigns dedicated to fisheries resource assessment and observation analysis using submersibles. Results demonstrate significant debris accumulation off major cities (Marseille, Toulon, Nice) or highly tourist cities including Western Corsica surroundings (Calvi, Ajaccio, Saint Florent). • Conversely, the Lion Gulf continental shelf is less affected. Boating and fishing are limited there while the Rhône plume, Mistral and Tramontane push waste toward western canyons (Lacaze-Duthiers, Banyuls) and eastern ones (Marseille). In some canyons, fishing waste can represent over 90% of waste (Lacaze-Duthiers Canyon). A significant decline in seabed waste numbers occurred over the past 14 years, more marked in the Lion Gulf. Typological study (Galgani et al, 2000 & 2011) gives a plastic percentage of 24% in the Lion Gulf and 31% in Eastern Corsica. Fishing-related items represent respectively 20% of the total in the Lion Gulf and 1% in Eastern Corsica. The plastic share has increased in recent years in Corsica, while fishing waste increased across all sampled areas. • Floating microparticle analysis at sea is recent with data from eight surveys conducted from 2010 to 2012 on French western Mediterranean coasts. Average concentration is high, with a density of 1,000 particles/ha. It is highly variable by sampled site and depends on marine currents. 'Industrial granule' data on beaches reveal significant abundance in the Fos Gulf (Cavaou beach). Generally, data are currently too limited to draw definitive conclusions. They must be supplemented by larger-scale measurements, particularly at sea where the largest microparticle quantities are found.

The presence of waste in the marine environment poses a risk of direct mortality or indirect impacts on marine life. To assess the trend of quantities and composition of waste ingested by animals, in the absence of a ubiquitous species, the Northern Fulmar is the selected indicator in the Channel-North Sea and Celtic Seas, and the turtle in the Bay of Biscay and Mediterranean.

• Data and monitoring of waste impacts on marine fauna became structured mainly within the OSPAR Convention for international cooperation on the protection of the marine environment of the North-East Atlantic (Ospar, 2009). Thus, an EcoQO (Ecological Quality Objective) on the stomach contents of fulmar specimens found stranded was implemented and today allows assessment. The synthesis conducted by the LPO (De Seyne, 2010) shows that data collected on Northern Fulmars in France (1972–2008) are limited. Of 372 birds, the cause of death was determined for only 115 individuals, 5% in Pas-de-Calais and 70% in Normandy had more than 0.1 gramme in the stomach. Limited data prevent trend evaluation. Within the Iroise marine natural park, some hooded cormorant colonies show a very high percentage (>95%) of nests containing macrodebrises. • The indicator built across the entire Channel within the Ospar convention shows an increase in the proportion of fulmars dead with more than 0.1 g of plastic in their stomach. At approximately 85% of specimens for 2007–2011, this is the highest level among different regions studied (South-East North Sea, Skagerrak, Eastern England, Scottish islands, Faroe Islands).

• An organized system exists for observing waste impacts on turtles, with data managed across the entire Atlantic coast, 30% of individuals showing waste, primarily in loggerhead and leatherback turtles. These species are recommended at European level as indicators of fauna impacts. • In the Mediterranean, 146 turtles have been collected since 2003 at the marine turtle research and rescue center. The 82 live turtles were released after care. For the 64 dead, autopsies revealed that ingested waste consisted mainly of plastics, nylon threads and fish hooks. • > Methodology > This fact sheet covers waste in four compartments: the coast, the seabed, the water column and the sea surface. It also addresses microplastics, particles 0.3 to 5 mm. > An inventory was conducted on all these compartments in the four French marine sub-regions to establish a baseline within the MSFD framework. > Available information on various indicators is partial and does not cover all marine sub-regions. For beach and sea waste, protocols exist and are validated. Microplastics monitoring is the subject of recent scientific work, and some data are missing. > Regarding waste impacts on fauna (ingested waste), due to the lack of ubiquitous species (living in different marine sub-regions), two species were selected: the Northern Fulmar for the Channel and Celtic Seas sub-regions, and the turtle for the Bay of Biscay and Mediterranean. • Author: Institut Français de Recherche pour l'Exploitation de la Mer (Ifremer).