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Marine Litter
Vital Graphics
CONCLUSIONS
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.
Conclusions