These materials can cause the marine animals to drown or suffocate thus killing them. Death can also be an effect of the materials strangling the animals or starvation when the animal is trapped and unable to reach any food. These materials can also cause severe injuries to the animals. Entanglement is especially important to sea lions and seals. These animals are known to have a curious nature like that of the domestic cat and are thus intrigued by this plastic debris. In sea lions and seals, an entanglement rate of just under 8% of the population of these animals has been recorded. By estimate, about 58% of the total species of sea lions and seals are thought to have been entangled at one time in their lifetime Allsopp et al. 6. These species include the Australian sea lion, Hawaiian monk seal and New Zealand fur seal.

Similarly, several species of whales, manatees, porpoises, seabirds, turtles, and dolphins have been found snarled up in plastic materials. This can be especially seen in manatees of which several animals have been freed by human divers from captivity in plastic debris. Some of these manatees were found to have scars or with their flipper injured or missing as they attempt to free themselves. In a research done on 78 sites using haul outs of Steller sea lions in British Columbia and the southeast of Alaska from the year 2000 to 2007, it was found that 386 individual lions were entangled in plastic debris. 49% of these were recorded to have debris around their necks. 1% of them had monofilament lines around their chest area. It was not possible to identify the material that had entangled these Steller sea lions in 77% of the animals and of the 33% (n=44) that was identifiable, the most common material that was entangled on the neck was packing bands (54%) and the second most common material was rubber bands (30%). Nets and ropes were tied at number three at 7% Raum-Suryan, Jemison and Pitcher 1489()

Fourteen of the entangled animals were branded in order to further investigate the effects these plastic debris. Out of these branded animals, one was found to be dead. Four were never seen again and are presumed dead while five were still entangled. Four others did not have their entanglements which were presumed to be ingested or to have disappeared through entering into the body through the skin Raum-Suryan, Jemison and Pitcher 1491.

From these results and these figures, we can see that plastic debris has serious adverse effects on these Steller sea lions and other marine animals.

The second way in which plastic debris causes deleterious effects on the marine animals is by ingestion. Ingestion is mostly seen in seabirds and sea turtles, though other species of animals have also been found to ingest plastic debris. These plastics are ingested since the preys confuse them for food or prey. The threat of ingestion is most detrimental in the situation where it blocks the alimentary canal or fills the stomach of the animal causing starvation and malnutrition. Death can also result. Plastic debris is passed to young ones of sea birds through regurgitation of food by the parent birds. Plastic debris, when ingested, also creates a false effect in the animals that they are satisfied and the animals are not able to put fat in their stores for hibernation, migration and reproduction.

Studies that have been conducted on sea turtles have shown that a large percentage, between 50 and 80% of the animals have in one time in their lives ingested plastic debris. In the research conducted concerning the snarl up of Steller sea lions, it was found that there were about 194 individual animals that had ingested plastic debris Raum-Suryan, Jemison and Pitcher 1488()

Another way in which plastics cause detrimental effects to marine life is because these plastics have the potential to attract pollutants or breakdown into pollutants of water. These pollutants include polychlorinated biphenyls or PCBs. This...

Another indirect impact is by the animals getting injured by these plastic debris either through ingestion or entanglement, they end up becoming weak and are thus easily preyed on by other carnivores in the waters.
In a research conducted, it was noted that plastic debris are sometimes used as nesting materials for the marine animals and thus leading to entanglement of young animals. The research was conducted on the Northern Gannet which is a large colonial seabird. Six nests of the birds were analyzed in Grassholm, Wales which is the third largest colony of gannets in the world. It was found that an average dry weight of plastic material used in nesting was about 469 grams. This was mostly synthetic fibers, netting material and packaging materials which constituted 83%, 15% and 2% respectively Votier et al. 169-70.

From these results, the researchers extrapolated that there is about 18.4 tons of plastic in the gannet nests in one single colony Votier et al. 170()

Possible solutions to the adverse effects of plastic debris

There is a need for measures to be taken to prevent and clean up plastic debris. These measures need to be done globally and inter-nation collaboration is important in the success of these measures. One example of this is the MARPOL which was created at the International Convention for the Prevention of Pollution from Ships. The MARPOL prevents ships from throwing waste overboard to the sea. It was enforced in 1998 and it is Annex V of the agreement which particularly deals with this. Annex V also requires that all ports which ships or boats dock at have garbage reception equipment and facilities for marine vehicles The Department of the Environment 8.

As of the month of April, 2005, one hundred and twenty two countries had signed the Annex V of the MARPOL. Ships from these nations which ratified the MARPOL are required to follow these regulations at all times while ships from the nations which have not ratified the MARPOL are expected to follow the regulations when they enter the waters of signatory countries Allsopp et al. 33()

Though the MARPOL agreement is currently in force, it is found that it is still greatly ignored and dumping of ship waste overboard is still on the rise. Currently, the rate of ship waste dumping stands at 6.5 million tons per year. However, this amount is thought to have been reduced by the enactment of the MARPOL regulations Allsopp et al. 33()

The Cartagena Convention came into being in the Caribbean in the year 1987 during the Convention for the Protection and Development of the Marine Environment of the Wider Caribbean Region. The Cartagena Convention in the Caribbean was enacted to curb both sea-based and land-based sources of marine debris. Many countries of the Caribbean are not signatory countries of the MARPOL agreement since they lack the facilities of waste reception which are a requirement of the MARPOL.

The Barcelona Convention was formulated in the year 1976 which governs the Mediterranean region. It was formed during the Convention for the Protection of the Mediterranean Sea against Pollution which is a UNEP programme. This convention governs litter from land-based sources. In European Union (EU) countries, there is the European Marine Strategy whose main purpose was to completely eliminate illegal discharge of marine debris by the year 2010. The EU also directed that all ports must have reception facilities for waste generated on ships and any residues of cargo that need to be disposed of.

By following all these conventions to the letter, it will be very easy to enforce and regulate against disposal of waste into the sea from both land-based and sea-based sources. However, enforcing laws in the sea can be quite difficult since it is not that easy to check whether they are being followed. One of the key reasons for this is that it is very expensive and unrealistic to have guards to patrol the waters at regular intervals to ensure laws are being followed. Secondly, most marine waste that is thrown overboard sinks to the sea bed and is therefore not easily spotted.

The second method of controlling marine debris is clean up. Clean up should be a joint effort between local authorities in charge of beaches and maritime waters, non-governmental organizations (NGOs), volunteers and the general public. However, clean ups can be quite expensive too. In 1998, a total of about 6 million dollars was spent in clean ups in 64 local communities along the North Sea. However, clean ups are the most effective way of controlling and removing plastic marine debris. As a result of clean ups, about 195 tons of derelict fishing gear was removed from the Northwestern Hawaiian Island according to a research published in the year 2003.

In Korea, it was felt that the coastline was lined with floating and submerged debris and a task force was formed to develop prevention…