Plastic Debris on Marine Species

¶ … Plastic Debris on Marine Species

Marine litter has been a huge nuisance to marine life and especially plastic debris. Marine debris is defined as any solid material which finds its way into the waters. This marine debris or litter has many negative effects to aquatic life. Close to 80% of all marine debris is of plastic nature Van et al. 1(; Weisman)

According to the Greenpeace Report on Plastic Debris in the World's Oceans, over 260 different species of marine life are known and documented to have been adversely affected by being trapped in marine litter or their ingestion Allsopp et al. 2.

These species include whales, seals, seabirds, sea lions, turtles and fish. Efforts should be developed and implemented to help alleviate these dangerous effects of plastic debris in order to preserve and protect marine life.

In a research conducted, the percentage of plastic in marine debris was calculated. It was found that in the North Eastern Atlantic, there were about 92% plastics in the sea bed marine debris. In the European Coasts, there were about 70% plastics in the sea floor marine debris and South Australia there were about 62% plastics in the beach marine debris. In South Africa, the amount of beach marine debris that was plastic in nature 88% and New Zealand, it is 75% Jose G.B 843.

These figures were aggregated from several researches done all over the world on marine debris, and the global trend is that between 60 -- 80% of marine debris is plastic in nature.

Plastics are artificial compounds, most of which are built from polyesters, and usually have different shapes, colors and sizes depending on the compound and dyes. Plastic waste is of utmost importance since in all our daily activities, we come across plastic materials. The worst part of these plastic materials is that they are not easily decomposable or degradable. However, they easily break down into smaller particles and simpler compounds. Small plastics whose size is less than 5mm in length are referred to as micro plastics Arthur 2.

This process of breaking down into smaller particles is extremely slow and may take years and even decades. Even though these plastics may break down into smaller particles, they cannot be mineralized into their individual components such as carbon dioxide gas, water and the inorganic molecules. Plastics are best disposed into landfills and compost piles where the heat conditions and other conditions such as moisture and bacteria can help in the decomposition process. However, in the ocean, the conditions are less favourable. Water hinders the process of degradation of plastics Martins and Sobral 1()

Some of the common plastics are as in the table below.

Acronym

Name of compound

Common uses

PET

Polyethylene terephthalate

Soda bottles (PET bottles)

PE

Polyethylene

Supermarket paper bags and plastic bottles

PES

Polyester

textiles

PVC

Polyvinyl Chloride

Plumbing pipes

PVDC

Polyvinylidene chloride

Packaging especially of food

PS

Polystyrene

Food container, plastic plates and cutlery

HIPS

High impact polystyrene

Vending machine cups

PP

Polypropylene

Yoghurt cups, drinking straws and bottle caps

PC

Polycarbonate

Compact discs (CDs), plastic eye glasses

PA

Polyamides

Toothbrush bristles and fishing lines

PU

Polyurethanes

Thermal insulation material

HDPE

High density polyethylene

Milk bottles and detergent containers

LDPE

Low density polyethylene

Floor tiles and outdoor furniture

As can be seen from the table above, these plastic materials are found in everyday materials which are used by people enjoying their time at the beach. In a study done in the Western North Atlantic Ocean on the size, mass and composition of plastic debris, it was found that the most common plastic debris was low and high density polyethylene (LDPE and HDPE), polypropylene (PP), polyethylene terephthalate (PET), nylon 6 (PA6), polystyrene (PS), and polyvinyl chloride (PVC) Moret-Ferguson et al. 1874()

Plastic materials have also largely been used in the manufacture of fishing equipment due to their relatively cheap nature. Previously, natural fibers and metals were used to make fish nets and fishing lines. However, today, many of these are made using plastics.

The problem created by plastics also arises as a result of the huge number of people who visit beaches all over the world every other day. Popular beaches can see thousands of people visit the beach every day and this creates a massive problem in terms of waste management and this is one of the chief reasons why plastic debris in marine water is increasing.

Sources of plastic debris

The activities which act as sources of plastic debris can be categorized into four cardinal categories.

1. Tourism related litter -- this is litter that is left by tourists visiting the beach. They include food packaging materials, food containers, plastic toys, beverage packaging materials, cigarette matter, etc.

2. Sewage-related waste -- this type of waste gets into the sea through storm drains and combined sewer systems which carry both runoff water and sewage. When these are discharged into the oceans, rivers or lakes, they can introduce plastic debris into marine waters. Some of the plastic debris that can be introduced through this method includes food packaging materials, used condoms, plastic toys, beverage packaging materials, etc.

3. Fishing related waste -- this type of waste is introduced as a result of the activities of fishing. These include when fishing nets or pieces of fishing nets and fishing lines are accidentally left in the waters or these pieces may break away and enter into the waters.

4. Wastes from boats and ships -- this last category incorporates all the waste from people and ships and pieces of these ships breaking off and entering into the water. These may be accidentally or intentionally dumped into the sea.

A different classification of the sources of marine plastic debris divides them into two broad categories which are land-based sources and sea-based sources. Land-based sources are those where the debris is washed, blown or discharged into the sea from the land. The UN GESAMP (United Nations Joint Group of Experts on the Scientific Aspects of Marine Pollution) suggests that about 80% of marine debris comes from land-based sources. Land-based sources can be as a result of five principal activities. First is storm water which is water that collects during heavy rains. Rain water can sweep off street litter into the storm drainage system and these are then discharged into rivers, lakes and oceans. The second activity is combined sewers which are sewers that carry both storm water and sewage. During heavy rains, these combined sewers have an enormous capacity that cannot be handled by the sewage treatment plant and may end up being discharged into rivers, lakes and oceans introducing these plastics. The other activities are littering and industrial activities which may introduce these plastics to the marine waters. Lastly, there is the disposal of solid waste in the sea. Sea barging was one of the widely used solid waste disposal methods and this introduces these plastic wastes to the sea.

The second category is sea-based sources. Here, there are four major activities which introduce the plastic debris either accidentally or deliberately. These sea-based methods are largely from the activities at the sea from boats and ship which are commercial fishing, recreational boating, and oil tankers, military and merchant vessels. Offshore oil and gas plants also lead to introduction of plastic debris into the ocean waters.

Plastic debris has also been thought to be as a result of alien space-crafts crashing into the sea during alien invasions. Though this can be easily dismissed by a simple argument that aliens do not exist, this possibility cannot be completely ignored.

Size and amount of plastic debris

There are basically three types of marine plastic debris.

1. Floating debris -- this is the debris which is lighter than water and thus floats on the water. From the results of several studies, it was found that the amount of debris in most areas was between 0-10 items per square kilometer. However, in the English Channel, higher values were recorded in the range of 10-100+ items per square kilometer. Indonesia had the highest amount of debris at more than 4 items for every square meter. It is thought that this floating debris is mostly contributed by wastes from boats and ships and fishing expeditions.

2. Seafloor debris -- this is the type of debris that is heavier than water and thus sinks to the floor of the sea. From several studies conducted in the waters around the world, it was found that waters in the Europe region had the second highest quantity of debris at the floor of the sea. The average was about 101,000 items per square kilometer. However, in this category, again Indonesia had the highest amount debris at little below seven hundred thousand items per square kilometer.

3. Shoreline debris - the last type of debris is that which can be found at the shoreline. This type of debris is usually found at the shoreline. Indonesia was the runner up here with about 29 items per meter while Sicily in Italy had the highest values with about 231 items per meter. In Indonesia, this shoreline litter covers about 90% of the upper shore.

How plastic debris affect marine life

There are two major ways in which detrimental effects to marine life occur. One is when these marine animals become snarled up in the marine debris and the other way is when they ingest the plastic wastes. Some of the materials which can cause the snarl up are pieces of fish lines or nets and rings which are used to bind six-pack beverages. 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 is an indirect impact of plastic debris. 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.