Thursday 17 December 2015

An ocean full of plastic

Introduction
Marine animals, already being susceptible to the dangers of other man-made processes, must be also confronted by the threat of plastic debris. The accumulation of anthropogenic debris (in particular plastic pollution) have resulted in huge threats on marine biota. The plastic threat is a growing global phenomenon. People have seen the ocean as an inexhaustible food source as well as a dumping ground without thinking about the consequences thereof. However, the ocean isn’t limitless and sustainability of our seas isn’t taking place. Marine litter is degraded at a very slow rate, and coupled with the exponential pace and quantity of debris that is disposed, ultimately leads to an unfortunate increase in plastic pollution. Thus, greater awareness on this significant problem is required.

Defining marine plastic debris
Marine debris is defined as any persistent manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment. It includes items made or lost by people, and those deliberately discarded into or unintentionally lost in the marine environment (Gall & Thompson 2015). Glass, metal, paper, and plastic are some of the most commonly found marine debris materials.

Source: Ocean Leadership Organisation

Ocean plastic statistics
Source: Ocean Conservancy
Plastic debris is of specific concern due to its abundance and persistent occurrence in oceans. One reason for a rapid decline in biological diversity is because of unsustainable human activities and as a result of this have accelerated extinction rates.

Land-based sources are responsible for around 80 per cent of all marine pollution. Global production of plastics has increased considerably over the last few decades from 5 million tonnes per year in the 1960s to 280 million tonnes per year in 2011. There are estimated to be over 5 trillion plastic pieces weighing over 250,000 tonnes afloat at sea ((UN, 2004 & Eriksen et al., 2014 as cited in WWF Living Blue Planet Report 2015; Gall & Thompson 2015).

It is estimated that about 6.4 million tons of marine litter are disposed in the oceans and seas each year. According to other estimates and calculations, some 8 million items of marine litter are dumped in oceans and seas every day, approximately 5 million of which (solid waste) are thrown overboard or lost from ships. Furthermore, it has been estimated that over 13,000 pieces of plastic litter are floating on every square kilometre of ocean today (UNEP. 2005. Marine Litter: An analytical overview).

There are approximately 35,500 tonnes of microplastics (tiny plastic particles) floating in our ocean (Eriksen et al., 2014 as cited in WWF Living Blue Planet Report 2015). Even with improved waste disposal management and recycling initiatives, a large amount of plastics will be swept into watercourses, which will eventually end up in the oceans. Over 60% of the world population live within 100km. Furthermore, because of rapidly growing global population, land-based activities it will ultimately lead to marine pollution taking exponentially place. 

Reasons why this phenomenon occurs and its various contributors
Reasons why plastic is utilised
Plastic materials are commercially successful as they are durable and economically affordable. Moreover, because they are low cost, plastic is readily available and utilised as a disposable material source. The very qualities of durability that make plastic convenient to use, however, also make it a persistent, non-degradable, permanent presence in the marine environment. When discarded, lost, or abandoned in the world's seas, plastic debris adversely affects living creatures there. (Joyner & Scot Frew 1991).

Types, sources, and locations of ocean plastic debris
Plastic pollution poses a serious threat as it is concentrated in areas where marine life is abundantly found. Marine debris can travel vast distances. Plastic fragments on beaches are derived either from inland sources and are transported to coasts by rivers, wind, man-made drainage systems or human activity, or directly from the oceans where low density floating varieties accumulate and are transported across great distance. Marine litter can blow around; remain floating on the water surface; drift in the water column; get entangled on shallow, tidal bottoms; or sink to the seabed at various depths. It is found in oceans and seas, in salt marshes and estuaries, in mangroves, on coral reefs, and on all kinds of shores. Beachgoers also contribute tremendously when they accidentally lose, carelessly handle, or leave behind plastic materials. There are major inputs of plastic litter from land-based sources in densely populated or industrialized areas, most in the form of packaging. Types and amounts of plastic debris on beaches are controlled mainly by topography, current and storm activity, proximity to litter sources and extent of beach use. Deposition and retention of plastics on beaches however, are largely controlled by the composition and degradation rates of the plastic particles (Corcoran et al. 2009; Derraik 2002; UNEP Marine Litter: An analytical overview 2005).



Source: Denver Post
Impacts on people and marine species
Unfortunately, plastic debris into the ocean has become an increasingly growing problem and the density thereof has also taken place at an astronomically fast rate.

Human-related impacts
Undoubtedly knowledge about plastic’s harmful impacts on marine biota has increased and relates to environmental, economic, safety, health, and cultural impacts. It also detrimentally impacts human health, while simultaneously damages people’s livelihoods, as well as spoil the beaches aesthetically and for people’s enjoyment, it creates navigation hazards, and negatively affects tourism, too. Therefore it has negative socio-economic consequences.

Impacts on marine species
Conversely, the marine environment has been perniciously affected by the plastic revolution which have resulted in a serious environmental issue. Marine populations have fallen significantly as numerous important habitats have been destroyed. Importantly, plastic pollution significantly threatens ecosystems and is harmful to organisms, it increases the transport of organic and inorganic contaminants, it smothers coral reefs, disturb habitats from mechanical beach cleaning, and breakdown by chemical weathering and mechanical erosion is minimal at sea. Marine litter is also a source of accumulation of toxic substances in the marine environment, and environmental changes due to the transfer and introduction of invasive species (UNEP Marine Litter: An analytical overview 2005). The biological and ecological performance of certain individuals will unfortunately be compromised.

Species of crustaceans, fish, turtles, marine birds, and mammals are affected and the scope and severity of it varies according to the species and plastic type. Species listed on the IUCN Red List are particularly vulnerable as they are at a greater risk of becoming extinct. At least 17 per cent of species affected by entanglement and ingestion of marine debris are listed as threatened or near threatened on the IUCN Red List (Gall and Thompson, 2014; WWF Living Blue Planet Report 2015).
 
Non-degradable plastic
The greatest threat is the durable properties of plastic as plastic materials persist in the marine environment long after disposal and may take up to 400 years to degrade. What is worrisome is the fact that more and more plastic are disposed of every day, and accumulate in the oceans at an even faster rate. These non-biodegradable items attract encrusting organisms as drift plastics. The drifting debris acts as a kind of oasis, attracting other marine animals in search of prey (Joyner & Frew 1991). Unfortunately, the durable properties of plastic lead to killing repeatedly. Another potential danger is the accumulation of plastic debris on the sea floor as certain seabirds select specific plastic shapes and colours, mistaking them for prey.

Source: Envirocon.org
The impact of marine debris on marine life is of particular concern, resulting into ingestion of plastic debris and entanglement in packaging bands, drift nets and synthetic ropes and lines. More than half of all known species of marine mammal and sea bird have ingested or become entangled in marine debris. The severity of the impact of it vary according to the type of debris and vary between species, and even between individuals as some are able to withstand it better than others. Furthermore, fatalities of birds, turtles, fish, and marine mammals are well-documented.

(Warning, some of the pictures below are disturbing).

Entanglement
Entanglement in plastic debris, especially with regards to discarded fishing gear, poses a serious threat to marine animals. When an animal is entangled, it may drown, or impair its ability to catch food or to avoid predators, reduce its fitness as it leads to an increase in energetic costs of travel, or incur wounds from abrasive or cutting action of the debris. Sea birds with stomachs full of plastic waste and turtles entangled in plastic bags are a serious marine problem. Lost or abandoned fishing nets pose a particular great risk.

Source: Wikipedia
Sea birds
Recreational fishermen also contribute to the problem as they don’t properly discard plastic line and birds dive beneath the water for their prey but become ensnared in the nearly invisible plastic monofilament line. It also reduce food consumption, limiting their ability to lay down fat deposits and thus reduces fitness.

Source: Earth Rangers
Ingestion
Ingested plastic particles regularly remain inside species, leading to harmful effects. Many organisms ingest small plastic particles, working their way up to the food chain. Among seabirds, plastic ingestion is directly correlated to foraging strategies and technique, and diet. The durable properties of plastic prevent species from easily digesting it. Small fish and seabirds who ingest plastic debris lead to a reduction in food uptake, cause internal injury, and, sadly, death following blockage of intestinal tract. While feeding on schools of fish, whales can unintentionally ingest plastic debris. Other species mistake translucent plastic bags for squid. Afflicted animals may be eaten or sink to the sea bottom.



Source: Shutterhead

Source: Wikipedia



Turtles
All known species of sea turtle have ingested or become entangled in marine debris. Sea turtle hatchlings, which spend their juvenile stage along ocean fronts, can unintentionally consume plastic pellets. In later life, sea turtles sometimes frequent ocean fronts in search of food. These turtles are known to ingest plastic bags, which are mistaken for jellyfish which can be fatal (Joyner & Frew 1991). Young sea turtles are significantly vulnerable and their survival is at risk.


Source: Energy Digital
Source: Project Aware


Solutions to the problem
Plastic pollution has severely affected the marine environment. Usage of plastics continues to increase, while simultaneously accelerating the amount of plastics polluting the marine environment. The fact is that marine debris does not belong in the marine environment. The threat of plastics to the marine environment has been ignored for a very long time and its severity and serious have only been recognised recently. However, solutions have so far only been a drop in the ocean and more effective solutions are required. Gall & Thompson (2015) suggest that “finding effective solutions requires a holistic approach, considering the entire life cycle of items that become marine debris including green chemistry and design and manufacturing as well as effective waste management and prevention and removal of marine debris”. Nevertheless, attempts have been made to conserve the world’s oceans by way of international legislation. The biggest challenge here is to enforce it effectively in such a vast area as the world’s oceans.

Education is another valuably powerful tool and can be particularly effective in schools. Through this way children can change their own habits while concurrently positively impacting their local community, too, starting with their family and friends. Thus, they can be a catalyst for important change which would lead to a community be willing to act sustainably in order to make also an eco-friendly contribution and foster an enhancement of ecological consciousness. Derraik (2002) notes that “thinking globally and acting locally is a fundamental attitude to reduce such an environmental threat”. He further notes that “the general public and the scientific community have the responsibility of ensuring that governments and businesses change their attitudes towards the problem”.

These two aspects can successfully and effectively be the best way forward to solve such a dire environmental problem.

Conclusion
Beaches across the globe are strewed with plastic debris and pose an imminent and global threat to marine species. Marine habitats, including shorelines, estuaries, and the sea surfaces, are negatively impacted by manmade debris. An ecosystem degraded by pollution and fragmented by development will recover slower from the effects of overfishing and less resilient to the impacts of climate change (WWF Living Blue Planet Report 2015). It is axiomatic that plastic debris pollution, being an environmental hazard that threatens our oceans’ biodiversity, must be urgently addressed.

References:
Derraik, J.G.B. 2002. The Pollution Of The Marine Environment By Plastic Debris: A Review. Marine Pollution Bulletin 44 842–852.

Corcoran, P.L., Biesinger, M.C., & Grifi, M. 2009. Plastics And Beaches: A Degrading Relationship. Marine Pollution Bulletin 58 80–84.

Gall, S.C., & Thompson, R.C. 2015. The Impact Of Debris On Marine Life. Marine Pollution Bulletin 92 170–179.

Joyner, C.C. & Scot Frew, S. 1991. Plastic Pollution In The Marine Environment. Ocean Development & International Law 22:1, 33-69.

WWF. 2015. Living Blue Planet Report: Species, Habitats And Human Well-Being.

UNEP. 2005. Marine Litter: An Analytical Overview.