New Delhi:It is probably a common conception that marine debris consists of just a few pieces of rubbish scattered along the strand line of beaches and is of no harm to anyone. Unfortunately this is not the case. Marine debris has become a pervasive pollution problem affecting all of the world’s oceans. It is known to be the cause of injuries and deaths of numerous marine animals and birds, either because they become entangled in it or they mistake it for prey and eat it.

The rise in plastic refuse in the ocean and on beaches is killing turtles of all species, with a disproportionate impact on hatchlings and young turtles, research by the University of Exeter shows.

A recent worldwide survey covering the major oceans where turtles live revealed on Tuesday that over 1,000 marine turtles each year get entangled in Marine plastic debris. Marine debris is manmade waste that is directly or indirectly disposed of in oceans, rivers, and other waterways.

Researchers estimate that over 91% of the trapped turtles end up dead being trapped in discarded fishing nets, six-pack rings from canned drinks, plastic packaging, and kite string among others. They were also discovered entangled in discarded plastic chairs, wooden crates, weather balloons and boat mooring line.

They also suffered serious wounds from entanglement, leading to maiming, amputation or choking. Others that survived were forced to drag discarded rubbish or debris with them.

The report concluded that, based on the survey results that more than 1000 turtles are likely to die due to entanglement. But the figure is likely to be a 'gross underestimation' of the scale of the threat to turtles. Not all dead turtles strand on beaches, especially young animals, and some decay at sea. Some of the experts surveyed said that not all stranded turtles are found and that some are removed by local people to eat.

"Plastic rubbish in the oceans, including lost or discarded fishing gear which is not biodegradable, is a major threat to marine turtles. We found, based on beach stranding, that more than 1000 turtles are dying a year after becoming tangled up, but this is almost certainly a gross underestimate. Young turtles and hatchings are particularly vulnerable to entanglement," Professor Brendan Godleyhas said.

Other than that, Professor of Conservation Science and Director of the Centre for Ecology & Conservation at the University of Exeter's Penryn campus and also the lead author warned that as plastic pollution increases more and more turtles are likely to become entangled.

The research, published in Endangered Species Research, sheds light on the true threat of plastic pollution to marine turtles, which, other research has shown; also eat plastic rubbish, and marine creatures caught up in it.

Mortality from entanglement has increased substantially over the last century, as with marine mammals and birds.84 per cent of the 106 experts surveyed on the Atlantic, Pacific Caribbean, Mediterranean and Indian Ocean coast.

Plastic Debris in the World’s Oceans:

Over 100 million marine animals are killed each year due to plastic debris in the ocean. Currently, it is estimated that there are 100 million tons of plastic in oceans around the world. It is expected that another 60 billion pounds will be produced this year alone. In some areas, the build-up of plastics is estimated to span 5 million square miles. To put it into perspective, that is the equivalent of the area of the U.S. plus India. 

There are 5 major ocean gyres worldwide. In the Pacific Ocean, the North Pacific Gyre is home to the “Great Pacific Garbage Patch”, a large area that is approximately the size of Texas with debris extending 20 feet (6 meters) down into the water column. It’s estimated that this “plastic island” contains 3.5 million tons of trash and could double in size in the next 5 years.

Researchers have also estimated that for every 2.2 pounds (1 kilogram) of plankton in this area, there is 13.2 pounds (6 kilograms) of plastic. 

But how does that much plastic get there? Sources of Marine Debris:

The answer to this is that,it has been estimated that around 80% of marine debris is from land-based sources and the remaining 20% is from ocean based sources. The sources can be categorised into four major groups: 

• Tourism related litter at the coast: this includes litter left by beach goers such as food and beverage packaging, cigarettes and plastic beach toys.
 • Sewage-related debris: this includes water from storm drains and combined sewer overflows which discharge waste water directly into the sea or rivers during heavy rainfall. These waste waters carry with them garbage such as street litter, condoms and syringes.
 • Fishing related debris: this includes fishing lines and nets, fishing pots and strapping bands from bait boxes that are lost accidentally by commercial fishing boats or are deliberately dumped into the ocean
 • Wastes from ships and boats: this includes garbage which is accidentally or deliberately dumped overboard. 

Huge volumes of non-organic wastes, including plastics and synthetics, are produced in more developed, industrialised countries. Conversely, in less developed and more rural economies, generally a much smaller amount of these non-biodegradable persistent wastes are produced. However, in the future, as less developed countries become more industrialised, it is likely that they will also produce more plastic and synthetic wastes and this will increase further the threat of pollution of the marine environment and this debris can cause death by drowning, suffocation, strangulation, starvation through reduced feeding efficiency, and injuries.

However, studies have already shown that a high proportion (about 50 to 80%) of sea turtles in any population is known to have ingested marine debris. This can have a negative impact on turtle populations. In young turtles, a major problem is dietary dilution in which debris takes up some of the gut capacity and threatens their ability to take on necessary quantities of food.

Did you know?
Plastic bags are petroleum-based and do not biodegrade.

Sea turtles and other marine creatures mistake plastics and other garbage as food (such as jellyfish) and ingest it. This mistake causes blockages within their digestive system and eventual death. 

According to the US EPA, Americans use more than 380 billion plastic bags and wraps each year. It takes 12 million barrels of oil to produce this many bags.  Worldwide, as many as one trillion plastic bags are used each year. This equates to 100 million barrels of oil!  

Plastic toxins end up in fish, which end up on our plates, which end up inside our bodies.

In 2007, San Francisco was the first city in the United States to ban petroleum-based plastic bags in large markets and pharmacies.
Less than 5% of plastics are recycled worldwide!

Solutions:
 There are a number of global, international and national initiatives in place that are aimed at protecting the oceans from marine debris. The most far reaching of these is the International Convention for the Prevention of Pollution from ships (MARPOL). Annex V of MARPOL was introduced in 1988 with the intention of banning the dumping of most garbage and all plastic materials from ships at sea. A total of 122 countries have ratified the treaty. There is some evidence that the implementation of MARPOL has reduced the marine debris problem but other research shows that it does not appear to have any positive impact. It must also be remembered that an estimated 80% of marine debris originates from sources on land. Even with total global compliance with MARPOL these sources would remain. 

Other measures to address marine debris include manual clean-up operations of shorelines and the sea floor as well as school and public education programmes:The public can get involved in this issue by:

• Reduce, Reuse and Recycle plastics;
• Use reusable cloth bags instead of plastic bags when shopping;
• Support local, regional and nationwide bans on plastic grocery bags;
• Don’t litter. Instead, volunteer at local beach clean-up events;
• Make sure to properly secure your garbage to prevent any fly-away plastics;
• Don’t release balloons into the air. They travel far and end up in our oceans being consumed by sea turtles that mistake them for food.

While the above measures are important at preventing or reducing the problem of marine debris, the ultimate solution to waste prevention is to implement a responsible waste strategy, namely the concept of “Zero Waste”. Such a strategy encompasses waste reduction, reuse and recycling as well as producer responsibility and eco-design. Ultimately, this would mean reduction of the use of plastics and synthetics such that they are only used where absolutely necessary and where they have been designed for ease of recycling within existing recovery infrastructure. It is possible that biodegradable plastics could be used where plastic was deemed necessary but could not be seen as an environmentally sound alternative unless they are known to break down rapidly to non-hazardous substances in natural environments.

References:
http://www.seeturtles.org
https://phys.org
https://www.express.co.uk
https://conserveturtles.org
http://www.greenpeace.org