An Invisible Problem

Plastic in the deep: an invisible problem How the seafloor becomes a plastic trap 2 Plastic in the deep: Plastic in the deep: 3 an invisible problem an invisible problem © OCEANA / Carlos Suárez 1. Executive summary Contents Most marine debris remains hidden in the 1. Executive summary 3 depths where, year after year, currents 2. An invisible problem: Plastic traps 4 increase the concentration of waste, including Submarine canyons 6 macroplastics. Many estimates have been made of how long it takes for different plastic Escarpments 8 objects to degrade, but these approximations Pockmarks 9 mainly relate to surface water. Seamounts and reefs 10 They are not valid for the deep seas, as these Depressions 12 environments are characterised by a lack Submarine caves and other structures 13 of sunlight, low temperatures, and limited The deep sea 14 erosion. For this reason, marine debris can 3. The ecological vulnerability of plastic traps 16 disrupt these ecosystems for centuries before it eventually degrades. 4. Oceana’s recommendations 18 5. References 20 Much of Europe’s waters are deep. Canyons, seamounts, escarpments, and reefs trap plastics, while simultaneously Credits act as biodiversity hotspots. Observations Suggested citation: Aguilar, R., Marín, P., Álvarez, H., Blanco J., Sánchez, N. Plastic in the deep: made during Oceana’s expeditions show an invisible problem. How the seafloor becomes a plastic trap. Oceana, Madrid, 24 pp. accumulations of single-use plastics in areas of DOI: 10.5281/zenodo.3992717 high biological value, abandoned fishing gear in The deep sea, Text: Ricardo Aguilar, Natividad Sánchez, Pilar Marín, Helena Álvarez the middle of the ocean, and half buried sheets Geographic Information Systems: Jorge Blanco an oasis for marine life of plastic hundreds of metres below the surface. Review: Allison Perry, Vera Coelho The deep seafloor has traditionally Editorial Support: Ángeles Sáez, Irene Campmany Very often, recovering this debris is technically been described as an oasis for life Design: Yago Yuste and economically unfeasible, either because Cover photo: Balloon and plastic bottle at a depth of more than 500 m in Sidon, Lebanon. or a biodiversity hotspot, due to the it is located at a great depth or because it enormous abundance and richness 1,2 All photos are © OCEANA unless specified otherwise in the caption. The information contained in this report may is snagged on fragile biological structures. of species that inhabit this area. be reproduced provided that © OCEANA is acknowledged as the source. Therefore, to reduce the damage, it is essential The contents of this document are the sole responsibility of OCEANA and the opinions expressed herein do not necessarily reflect the official position of the European Commission. The European Commission is not responsible to drastically reduce the everyday use of This zone is of particular importance for any use that may be made of the information contained in this document. plastic and avoid its uncontrolled dumping. for marine biological diversity and, Oceana calls on all social agents to reduce in fact, many species use deep sea the irrational use of plastic and implement an environments as spawning, nursery, ambitious regulatory framework that responds breeding, or feeding grounds. decisively to one of the greatest challenges Canyons and seamounts house posed by debris and plastic in the marine emblematic species, from corals to environment: the pollution of the deep sea. cetaceans and sharks. 4 Plastic in the deep: Plastic in the deep: 5 an invisible problem an invisible problem Abundance of certain geohabitats in the Northeast Atlantic and Mediterranean. Source: 2. An invisible problem: Plastic traps Seamounts Escarpments Esri, Digital Globe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community Submarine canyons The deep sea Most of what is known or assumed about The vast majority of these marine plastic in the oceans comes from coastal expanses have scarcely been studied, and observations. However, analysing the often scientists find that the litter arrived litter collected on beaches barely hints at before they did. In fact, it is estimated the magnitude of what lies hidden at the that only 1% of plastics are in surface bottom of the sea. waters, and the majority of the remaining 99% ends up in the deep sea3. For fifteen years, Oceana has been using an underwater robot (ROV, Remotely Due to their morphology, some geological Operated Vehicle) to document European formations concentrate marine debris. As and Mediterranean waters up to a thousand can be seen on the map on this page, these metres deep. Debris has been a constant are widely distributed habitats. on virtually every dive, excluding in certain areas where strong currents carry the litter Below, we detail some of these cases that far from the shore. are transforming from biodiversity hotspots to underwater landfills. From an ecological point of view, deep waters are considered to be 200 metres or more below sea level, where the influence of light begins to disappear. This depth is reached very close to the coastline in some regions, but in this report, we also demonstrate that marine plastics have been found at great distances from inhabited areas. The vast majority of these marine expanses have scarcely been studied, and often scientists find that the litter arrived before they did”. 6 Plastic in the deep: Plastic in the deep: 7 an invisible problem an invisible problem Submarine canyons -434 m 1:20000 500 1.000 m 0.25 0.5 nm Some submarine canyons, such as the Capbreton Canyon (France), are the extension St. Vincent Canyon, Portugal of rivers. This makes it easier for waste to reach the open sea and great depths. Sampling in the St. Vincent Canyon (Portugal)14 estimated an average of 1.67 objects per hectare, with Source: National Geographic, Esri. HERE, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GERCO, NOAA, INCREMENT P.CORP. concentrations exceeding 300 objects in some locations. These underwater structures are, in some Around 15% of the world’s submarine In Europe, the case of the Mediterranean cases, associated with existing or former canyons start close to the coast, is particularly worrying, as in some terrestrial rivers, and represent their increasing the amount of sediments and submarine canyons the concentrations of continuation onto the seafloor. anthropogenic waste they receive, and waste reach staggering figures. In certain The Mediterranean holds In general, canyons tend to originate as a facilitate the transport of plastics and canyons along the coast of Catalonia, result of erosion by water and transported other waste to the seafloor.12 concentrations of marine litter have been the submarine canyons with sediments, which generate valleys of estimated as being between 1,500 and the highest concentration of varying depths. In other cases, they have 15,000 objects per square kilometre, with plastics in Europe. been attributed to factors such as mud a maximum of 167,540 in one particular flows, landslides, subsidence, or glacial location. Of the items found, the majority activity, among others.4,5,6 (72%) were plastics.8 Recent studies have shown the important role rivers play in transporting plastics 42% Plastics from the land to the sea.7 Like land-based valleys, submarine canyons collect, channel, 16% and accumulate, meaning a great deal of Fishing gear waste ends up reaching the canyons and building up in large quantities. From these A study of fifteen canyons in the -610 m areas this debris is then transported to Bay of Biscay found litter in all the deep sea.8,9,10 This high concentration of them, with plastics (42%) and of waste is also influenced by the strong fishing gear (16%) being the most currents that can occur in the upper zone commonly encountered objects. Much of this fishing gear was of these geological formations.11 also plastic, including gill nets, trawl nets, and longlines.13 Batrun, Lebanon In other canyons, such as those in Lebanon (Jounieh, Batrun, Beirut, and Sidon) the concentrations of domestic waste far exceed the densities found in the St. Vincent Canyon. It is not known how long it takes for plastic to degrade at great depth. 8 Plastic in the deep: Plastic in the deep: 9 an invisible problem an invisible problem -500 m -541 m Escarpments Pockmarks Émile Baudot Escarpment, Balearic Islands Mallorca Channel, Balearic Islands Where there are no submarine canyons to Pockmarks are crater-shaped formations It is increasingly common to see commercial Forkbeard (Phycis sp.) next to plastics transport the waste, it reaches the deep species like this forkbeard (Phycis sp.) among formed by gases escaping through the between the Ausias March and sea via escarpments15,16, in the same way as agglomerations of urban debris. Recycled or not, submarine crust.20,21,22 Ses Olives seamounts. coastal runoff. plastic invades the depths. Their concave shape means they become These underwater cliffs result from traps for waste carried by marine currents various tectonic, geological, and erosional which, once deposited, is difficult processes. They can be interrupted by to remove. valleys and canyons, which increase their complexity.15,17,18 Many of these cliffs may have small platforms or terraces19 at different depths that retain some of the sediment and debris that would otherwise end up in the deeps. Pockmark plastic trap diagram Large concentrations of plastics can be seen in these places. Scanner, United Kingdom. Escarpment plastic trap diagram Plastics in the Scanner marine conservation area (North Sea). 10 Plastic in the deep: Plastic in the deep: 11 an invisible problem an invisible problem -30 m -323 m Seamounts and reefs Sa Creu Cape, Balearic Islands Abubacer Ridge, Alboran Sea The Single-Use Plastics Directive requires fishing gear manufacturers to defray the costs of awareness- Submarine rises are oases of life.

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