This paper was presented at “Coastlines ‘97” (EUCC) Naples. 2-6 June 1997
The impact of “small garbage” on the marine environment with emphasis on the Mediterranean marine turtle population L. Venizelos1 and M. Smith2 1.
President, Mediterranean Association to Save the Sea Turtles - MEDASSET, c/o 24 Park Towers, 2 Brick Str., London W1Y 7DF, (U.K.), Tel. & Fax No. +171 6290654 1C Licavitou Str., 10672 Athens, (GR), Tel. No. +301 3640389, Fax No. +301 3613572
2. Undergraduate, Royal Holloway College, University of London, 40, South Road, Taunton, Somerset TA1 3DY, UK
Abstract A human population explosion since the second world war coupled with the associated rise in waste produced has resulted in our oceans becoming a dumping site. This has had a severe and increasingly damaging effect on the marine environment and the diverse array of organisms which inhabit it.
Introduction Increasing environmental awareness and global responsibility have become key political issues especially since the 1992 Earth Summit, in Rio de Janeiro. Environmental pressure groups, both locally and internationally, have successfully raised the awareness of the public as a whole and there is a general feeling that the public wishes for a cleaner and safer environment both for our children and the other creatures with whom we share this planet. It is therefore vitally important that the results of scientific research and investigation should be made widely available so that this knowledge can be shared by the eager public who can, in turn, put the knowledge into practice with great effect as is exemplified by the recycling programmes undertaken by the United States during the 1980’s and 1990’s (POPE, 1990). This paper attempts to bring together the information concerned with problems of “small garbage” waste materials in the marine environment, and by so doing highlights the problems to the public. It is vital that the issue of marine garbage should be addressed and dealt with now, or else the highly complex marine environment, especially the Mediterranean, will be altered beyond repair. There is a special emphasis in this report towards Mediterranean marine turtles as this is the first and foremost concern of MEDASSET.
The Mediterranean marine environment
The Mediterranean sea, is perhaps unique amongst the other seas and oceans, but because of its special features it highlights all the global problems associated with marine pollution. The Mediterranean sea covers an area of approximately 2,5 million square miles and is seen as a highly productive ecosystem. The coastlines of many countries with markedly different cultures and political frameworks surround the Mediterranean, making legislation concerning environmental law, difficult to achieve and sometimes impossible to enforce. Many major rivers flow into the sea often bringing in pollutants, which are becoming concentrated due to the Mediterranean being almost self contained with water renewal rates estimated to be in the region of 80 - 300 years (UNEP, 1996). The Mediterranean has a major problem, reconciling the interests of the marine organisms and the rapidly growing tourist industry which brings in much needed capital to often underdeveloped regions. It was estimated that in 1990 a total of 167 million tourists visited the coastal resorts of the Mediterranean. There is also a constantly increasing fleet of cruise ships which transport hundreds of thousands of tourists around the more scenic and threatened areas of the Mediterranean. These cruise ships use mass catering producing alarming levels of waste which, until recent attempts to enforce the law, tended to be dumped overboard. The interests of the undoubtedly important tourists have to be carefully balanced against the threat to marine creatures many of whom are seriously endangered. The more appealing species are more likely to have associated conservation bodies protecting them. The variety of cetaceans seen in the Mediterranean is remarkable. Approximately 20 different species have been recorded including the Bottle nosed dolphin (Tursiops truncatus), the common dolphin (Delphinus delphis) and the Sperm whale (Physeter macrocephalus). The Mediterranean is also host to the Monk Seal (Monachus monachus) and two of the seven species of marine turtles, the loggerhead (Caretta caretta) and the Green turtle (Chelonia mydas), both of whom have globally important nesting sites here. With fewer nesting beaches available to the turtles mostly due to the under controlled tourist industry, the problems associated with pollution are of particular concern. It is estimated that the tourists bring 15 million tonnes of garbage a year, of which a large proportion is left or dumped carelessly on the beaches.
Pollution by small garbage Small garbage can be viewed as any solid material which in its present state or by degrading into another state results in a deleterious effect on the marine environment. It is mostly therefore associated with the activities of humans. The sources vary from rubbish discarded by individual beach users; ocean dumping by ships; wreckage of ships, high waves removing large amounts of street rubbish from sea fronts, garbage lost or deliberately dumped by the fishing industry, the navy, and the beach side restaurants and hotels. Of the garbage produced by the fishing industry, monofilament netting made of artificial fibres is the most dangerous. Fishing fleets often carry hundreds of miles of
this netting which is cheap to produce, and once snagged it is often cut and dumped at sea rather than untangled. Trawl floats, ropes and other associated wastes are also found in significant levels. Of domestic waste the list is seemingly endless. Metals, glass, fibres and plastics are all now part of our marine environment. Of these, plastics are the most deadly as they are light weight, very strong and durable, very cheap to produce and most importantly widely available. They are water and microorganism resistant which means the breakdown is extremely slow. In 1985 the United States alone produced 1.2 trillion cubic inches of plastic so it is hardly surprising that plastic is the most common of the marine pollutants. One three-hour-long clean up of 157 miles of Texas shoreline in September 1987 reaped: 31,773 plastic bags 30,295 plastic bottles 15,631 plastic sixpack holders 28,540 plastic lids 7,460 plastic milk containers 1,914 disposable diapers 1,040 tampon applicators. (WEISSKOPF, 1988) A Mediterranean average of 1 - 3 tonnes per mile of coastline was recently estimated after a clean up on the French coastline.
The effect on the marine environment Plastics have essentially two effects. Firstly there is a physical effect. Monofilament netting is invisible in the water and entanglement in discarded fishing nets is estimated to account for the loss of 50,000 North Pacific Fur Seals annually, some ten times more than those killed by hunters. Due to the wide range of plastic shapes, sizes and colours, species are apt to mistake these items for food. A transparent plastic bag looks very similar to jellyfish (the favorite food of many sea turtles) (STUNTZ, 1995), resulting in either the blockage of the digestive tract or suffocation of the turtle, once the bag has been ingested. Plastics also contain air bubbles preventing turtles from diving for their food. It has been discovered that one marine mammal had 50 bags in its stomach (MROSOVSKY, 1981). CARR (1987) suggests that hatchling turtles congregate around drifting debris for shelter and food supplies. This debris used to consist of natural organic waste, but now is dominated by floating plastics. Being inexperienced feeders these turtles ingest the plastics and although their appetite feels satisfied, in reality they are starving to death. Sea mammals, being playful creatures, often entangle themselves in the plastic loops of six pack holders. As the animal grows the plastic tightens strangling the animal. Although seen as pests by many people, Gulls are often the most affected. Hereditory behavior dictates that shiny objects are appealing. Fifty out of 250 species of seabirds are known to ingest plastics, mostly plastic beads. These small objects accumulate in the food chain.
1. Loggerhead turtle entangled in discarded fishing net Photo: M. Erhardt / CMC
2. One kg of accumulated plastics found in the stomach of a marine turtle Photo: G. Balazs / CMC
3. “This was once a prime nesting site for turtles in the Mediterranean� Photo: M. Kasparek / MEDASSET
4. Gulls feeding on seaside garbage tip with plastic waste Center for Marine Conservation Washington, D.C.
The second effect is that of chemical poisoning. Plastics take many years to decompose and if they are in restricted light areas, such as the ocean, this process takes considerably longer. Plastics contain significant quantities of PCB’s (Polychlorinated biphenyls) and these can be released during the breakdown of the plastics. It has been established that the levels of PCB’s in sea birds was positively correlated with the amount of ingested plastics (RYAN, 1988). PCB’s in the body are known to have adverse effects on metabolic processes including the suppression of the immune system, reproductive failure and even death. Recent surveys have resulted in the following alarming readings: In Loggerhead turtle an estimated average of 0.032 - 0.201 mg/g of PCB was found (CLARK, eggs KRYNITSKY, 1980), while an adult Leatherback turtle had a contaminant concentration of 1.2 mg/g of PCB (DAVENPORT, et.al., 1990) (HUTCHINSON, SIMMONDS, 1992).
What can be done? Marine garbage litter is a cultural problem and has to be dealt with through education, legislation and law enforcement and a change in the production methods for plastics. Public education can result in a number of successful outcomes. Recycling has already proved to be a success, so if recycling bins are placed on beaches, it is likely that a vast majority of litter would be recycled. The cost of commercially clearing litter is massive so regular voluntary beach clearing exercises would deal with localised problems. Obviously nothing can be done about litter scattered across the open sea, so it is vital that when it reaches the shore it is collected. Legislation such as the London Dumping Convention 1972, and the International Convention for the Prevention of Pollution from Ships 1973. Article 4 and Annex 1 of the Barcelona Convention Protocol for the prevention of Pollution of the Mediterranean sea by dumping from ships and aircraft, accepts the Mediterranean as a “special area”. Since most of the beaches are public, it is up to the local authorities to provide litter bins and to enforce the law. Attempts should be made to discourage unnecessary use of plastic products in favor of biodegradable and recycled products such us cardboard and glass. At the moment it is up to the individuals’ conscience to obey the law, so more government initiatives are needed.
Conclusions Marine small garbage pollution is a massive worldwide problem. Obviously little can be done about the past, but there is now an opportunity for us all to have a radical reappraisal of our garbage problem. Even small changes to our attitudes and habits can improve our environment for future generations.
References CARR, A. (1987), - Impact of nondegradable marine debris on the ecology and survival outlook of sea turtles, Marine Pollution Bulletin, 18 (6B), 352-356. CLARK, et. al. (1985), - DDE residues and artificial incubation of Loggerhead sea turtles eggs, Bulletin Environmental Toxicology, 34, 121-25. DAVENPORT, et. al. (1990), - Metal and PCB concentrations in the “Harlech” Leatherback, Marine Turtle Newsletter, 48, 1-6. HUTCHINSON, J. ; SIMMONDS, M. Escalation of threats to marine turtles, Oryx 26, No. 2, April 1992. MROSOVSKY, N. (1981), - Plastic jellyfish, Marine Turtle Newsletter, 17, 5-7. POPE, (Ed.) (1990), - The Green Book. RYAN, et. al. (1988), - Plastic ingestion and PCB’s in seabirds: is there a correlation? Marine Pollution Bulletin, 19(4), 174-76. STUNTZ, N. (1995), - Determination of primary cues used for food recognition in Loggerhead sea turtle. NOAA Technical Memorandum NMFS-SEFSC-387. UNEP: Workshop on policies for sustainable development of Mediterranean coastal areas, Santorini island, 26-27 April 1996 MAP Technical Reports Series No. 114. UNEP, Athens 1996. UNEP/IOC/FAO: Assessment of the state of pollution of the Mediterranean Sea by persistent synthetic materials which may float, sink or remain in suspension, MAP Technical Reports Series No. 56 UNEP, Athens 1991. WEISSKOPF, M. (March 1988), - Plastic reaps a grim harvest in the oceans of the World, The Smithsonian, 59-66.
Key Words for: “The impact of “small garbage” on the marine environment with emphasis on the Mediterranean marine turtle population” L. Venizelos and M. Smith 1.
Mediterranean
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Environment
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Dumping
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Beaches
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Sea Turtles
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P.C.B.
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Garbage
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Legislation
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Education
10. Recycling