About marine litter
Litter at 800m in the Red SeaThe global threat of marine litter is growing day by day (UNEP, 2009a, 2009b), causing increasing and unprecedented harm to marine habitats and their occupants (SCBD, 2012), and, if unchecked, potentially irretrievable knock-on effects on marine ecosystems with consequent economic impact on food sources, jobs, and so forth. Sources of marine litter are many and varied; the main sea-based sources are merchant shipping, ferries and cruise-liners, but fishing vessels, pleasure craft, fish farming , and oil and gas offshore installations (and even research vessels) are also common sources, of general human-generated litter, as well as discarded equipment (such as fishing lines, oil barrels, and so on). Land-based sources also contribute much, including municipal landfill sites near the coast, as well as transport along waters, and to and from coastal landfill sites, discharge of storm water, and tourism around coastal areas. Estimates of the scale of this problem (UNEP, 2009b) are that around 6.4 million tonnes of litter enter our marine habitats every year, at the rate of around 8 million individual items of litter per day. This ~2.5 billion items per year causes a variety of problems for marine life, many of them devastating. Such include constant entanglement in plastic bags or similar (which often leads to a slow and harrowing death), and ingestion by animals (often turtles, seabirds, seals and similar) mistaking litter for food (another common cause of death or disablement). Meanwhile, litter accumulations or large individual items smother or damage the seabed, preventing light and/or food from reaching seabed flora or fauna, and generally hampering the life of bottom-dwelling creatures, harming many connected ecosystems. Other problems include toxic substances, invasion from unfamiliar species 'hitch-hiking' on litter items, and several more. Entanglement alone is known to affect 49 of the 115 known species of marine mammals, and it is estimated that between 700,000 and 1,000,000 seabirds are killed by either entanglement or ingestion every year. Marine litter is also a danger to power stations (for example, causing considerable cost in clearing cooling-water intakes), contaminates beaches, harbours and marinas, presents safety risks at sea, poses danger for cattle grazing in coastal areas, and threatens our health on the beach (broken glass, rusty metal, bandages, syringes, and so on).
The world has been slow to address this issue, but political will began to appear in 1987 when Environmental Ministers initiated the designation of the North Sea as a Special Area with regard to garbage accumulation, within the 'MARPOL' convention (concerning directives regarding pollution from ships). Since then, a number of directives have been issued from various governments and intergovernmental organizations. However, almost without exception, current directives and initiatives are directed towards aiming to reduce further waste accumulation, with little or nothing of scale attempted to deal with existing accumulations of marine litter. In part this is because any form of underwater intervention is difficult and hazardous, as well as costly, and few workable approaches to this problem are generally in the public or governmental eye. However, as we argue in the case of coral restoration and similar marine conservation opportunities, autonomous robotics has enormous potential for intervention in addressing this global concern.
SCBD (2012) Secretariat of the Convention on Biological Diversity and the Scientific and Technical Advisory Panel ? GEF (2012). Impacts of Marine Debris on Biodiversity: Current Status and Potential Solutions, Montreal, Technical Series No. 67, 61 pp
UNEP, 2009a, Marine Litter: a Global Challenge, UNEP (United Nations Environment Programme), http://www.unep.org/regionalseas/marinelitter/publications/docs/Marine_Litter_A_Global_Challenge.pdf
UNEP, 2009b, Marine Litter: Trash that Kills, (United Nations Environment Programme), http://www.unep.org/regionalseas/marinelitter/publications/docs/trash_that_kills.pdf