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Marine Litter

Vital Graphics


Production of single-use, throw-away plastic products

has increased exponentially since the 1950s. At the same

time, plastics are designed to be durable and it is precisely

this characteristic, combined with an unwillingness or

inability to manage waste effectively, that has created

a global issue. It is a complex social, economic and

environmental problem which knows no boundaries.

It threatens entire marine ecosystems, has enormous

economic consequences and affects the livelihoods of

millions of people.

The cause is human activity – on the land and in the seas.

All sectors and individuals contribute to this pollution –

from poorly controlled waste sites, illegal dumping and

mishandled waste on land to floating ropes, nets, floats

and other debris from fishing, merchant shipping, oil rigs,

cruise ships and other sources.

Larger “macroplastics” harm marine life when animals

and fish become entangled or eat them. However, more

research is needed to determine impacts on population

levels which can further affect endangered species,

sensitive habitats and ecosystems. All of these have

tangible and measurable socioeconomic consequences

for fisheries, shipping and tourism.

Out of sight but not out of mind

Microplastics measure less than 5 mm in diameter and are

either manufactured for industrial or domestic purposes

(“primary” microplastics such as microbeads in toothpaste)

or are a result of weathering and fragmentation of larger

material (“secondary” microplastics). Weathering and

fragmentation is assisted by exposure to UV radiation

and oxygen at or close to the water surface. However,

at lower levels the lack of light slows this process so that

it takes a long time for even “biodegradable” plastics to

break down.

There is a major gap in our knowledge about the actual

quantities of plastic debris and microplastics and the

proportion coming from from different sources. A further

challenge is that we cannot see a large part of the litter

because it lies below the surface. Even more worryingly,

we don’t know whether it is affecting the trophic chain;

the potential for bioaccumulation in certain species; what

chemicals are released into themarine environment when

plastic waste degrades; the impact on food safety or the

potential connections to climate change.

The fact that so much is out of sight explains why there are

no reliable estimates of the total quantity of plastic in the

ocean and why research on its effects on marine life and

human consumption is still in its infancy. However, there is

sufficient evidence that marine plastics and microplastics

are having an unacceptable effect. Immediate action based

on available knowledge needs to go hand in hand with

improved and adaptive management and governance

approaches that will evolve as more is learned.

Plastic debris and microplastics are by far the main components of marine litter and

are omnipresent in the world’s oceans – from remote shorelines to the deep ocean,

from the poles to the equator. The quantity of plastic observed in coastal waters off

densely populated regions and in the mid-ocean gyres, despite high concentrations,

represents only a fraction of the total amount in the marine environment. In addition,

many types of plastic waste are denser than water and will sink to the sea floor. Surface

accumulations in mid-ocean subtropical gyres are just the tip of the iceberg. While

uncertainties remain, it is estimated that open ocean floating plastic accounts for less

than 1 per cent of the total that has reached the oceans since it began to be produced.