PACIFIC SOUP: OUT OF SIGHT, OUT OF MIND, AND STUCK IN THE MIDDLE

Photo courtosy of: AN HONOURABLE GERMAN

Returning home through the North Pacific Gyre after competing in the Transpac sailing race in 1997, Charles J. Moore came upon a vast stretch of floating debris. His unfortunate discovery has since been dubbed the ‘Great Pacific Rubbish Patch’, a gyre of marine litter in the central North Pacific Ocean; estimates range from 250,000 square miles (the size of Texas) to 6 million square miles (10% of the entire pacific ocean), whilst recent studies have found six times more plastic than plankton. Often featuring prominently in the media, this phenomenon is often misinterpreted as a giant, visible solid island of rubbish, like an ocean landfill. The reality is in some ways worse; the patch in fact primarily (approximately 90%) consists of suspended plastic particles in the upper water column, rather than a solid mass, causing it to change density, shape and size, making it difficult to define. Despite its size and the considerably above average density of plastic debris in the water column, the patch is not visible from satellite or aerial photography.

The complex structure of most plastics means that most varieties do not biodegrade like other marine debris; instead they photodegrade, disintegrating into smaller and smaller pieces whilst still remaining as polymers, and leaching potentially toxic chemicals including bisphenol A, PCBs, and derivatives of polystyrene. Further chemical problems arise due to the oil base of plastics, which attract floating chemicals from the water. Many of these chemicals are persistent organic pollutants which never break down or leave the environment. Examples include chlordane, DDT and Furans.

Even in its micro state, plastic is still detrimental to marine life; the plastic flotsam concentrates into the upper levels of the water column where it is ingested by the smallest marine organisms, such as plankton, and filter feeding organisms such as bivalves, barnacles and jellyfish. From this level, plastic moves up through the food chain to larger the marine creatures that consume them, or enter directly as large pieces at higher levels, such as sea birds, marine turtles and even whales.  In these cases, large pieces may simply kill the animals by clogging up digestive tracts, where they are unable to digest them due to the physical size, or by entanglements where they cause lacerations, exhaustion and drowning.

Jellyfish are in turn eaten by larger fish, many species of which go on to be consumed by humans, who in turn ingest the toxic chemicals. When ingested, the chemicals released from plastic can cause toxic effects that lead to illness, and can be mistaken by the endocrine system causing hormone disruption.

Whilst green initiatives and public awareness may be on the increase, out of sight is still very much out of mind, and the amount of plastic pollution in the world’s oceans is still on the increase with an estimated 46,000 pieces of plastic per square kilometre of the world's oceans (six times more plastic than plankton), killing a million seabirds and 100,000 marine mammals and turtles each year. The world's navies and commercial shipping fleets make a significant contribution, throwing some 639,000 plastic containers overboard every day, whilst 80 per cent of marine plastic was initially discarded on land. Wind blows plastic rubbish out of littered streets, landfills, lorries and trains on their way to landfills. It gets into rivers, streams and storm drains and then rides the tides and currents out to sea. Even before starting a cleanup operation is considered, the source of plastic should perhaps be addressed first. With so many items made of this complex substance around us every day, perhaps we should reconsider our relationship with plastic...

By Will Matthews