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Will Plastic be our Legacy?

dr RACHAEL marshall _PROFILE

Story by Dr. Rachael Marshall


I have been a marine biologist for 10 years now and I have been exposed to a variety of marine, coastal and Island environments, conducted numerous necropsies on marine wildlife, attended countless whale and turtle strandings, and the one, most prominent and constant reminder of the human footprint on the environment is plastics, in all it’s wonderful, technological and damaging forms.

Whilst the developed world is shifting its focus and placing more emphasis on sustainability, recycling and reducing the amount of toxicants used in new synthetic products, the developing world does not have the luxury to invest in long term environmental stewardship, education and proper waste disposal when they struggle to provide the very basics (health care, food, water) to rapidly growing populations. The immense pressure that plastic (in its very slow degrading form) is placing on the earth’s ecosystems is starting to rear its ugly head.

In this article I aim to provide an overview of some of the latest research and information coming out of the scientific community on plastics and how it is changing our marine world.

Credit: What lies under by Ferdi Rizkiyanto

Credit: What lies under by Ferdi Rizkiyanto


Great Pacific Ocean Patch – the TRASH VORTEX

The Great Pacific Ocean Patch, also known as the Pacific Trash Vortex, is a gyre of marine debris in the central North Pacific Ocean (one of the five major oceanic gyres, see image below). It is an area of debris made up mostly of pelagic plastics, chemical sludge and other debris trapped in the currents associated with the gyre (Moore 2003). Some areas are so thick that they form almost mini man made plastic islands, on which marine striders (Holobates sericeus, a type of marine insect) have recently been found to lay their eggs, a phenomenon that has only recently started occurring due to the thickening of the plastic mass (Goldstein 2012). The findings of the study conducted by Goldstein were potentially very worrying. Goldstein writes that greater numbers of bugs could in theory deplete populations of the plankton they feed on, throwing a wrench into the ecosystem and causing impacts on other marine life. The downstream effects, not only on larger marine animals, but the whole ecosystem is when the true impact of these waste gyres will be recognised, but may not be known for decades.

Image: The patch is created in the gyre of the North Pacific Subtropical Convergence Zone.

Image: The patch is created in the gyre of the North Pacific Subtropical Convergence Zone.

In 2012, the Sea Education Association (SEA) conducted a research expedition to study plastic pollution in the North pacific Gyre. During the North Pacific Expedition, a total of 118 net tows were conducted and nearly 70,000 pieces of plastic were counted to estimate the density of plastics, map the distribution of plastics in the gyre, and examine the effects of plastic debris on marine life.

Are we in a new geological age determined by human impact? – the “Anthropocene”

Whilst this question isn’t a new one, the “Anthropocene” has been referred to since 2002 when Nobel prize winner Paul Crutzen said we should now consider that we are living in and age dominated by human activities, it is certainly gaining more momentum. Punch it into Google and you’ll get 795,000 hits, (that’s 700,000 more than in 2008). However, for it to be properly deemed a new geological age, the International Union of Geological Sciences must first declare it so. Whilst it looks like it will be difficult for it to be classified a new geological ‘age or era’ without the occurrence of a mass extinction (let’s hope it doesn’t come to that), it does seem to be plausible for it to become the term for a new epoch (a sub-division of an era). One thing seems fairly certain though; widespread agriculture is replacing natural vegetation with large expanses of single crops. Cutting down forests, draining marshlands and peat bogs, and transforming the grasslands has pushed out animal and plant species causing changes in distributions and extinctions. All of these changes will mean that one day, the fossil record of our time will look very different to the pre-Anthropocene record, and the prevalence of plastic in that record, may very well be one of the common denominators.

A recent discovery that really cements the idea of the informal ‘Anthropocene’ epoch, and coming back to the topic of plastics, was the discovery of plastics in the rock record in Hawaii. A study released just recently (June 2014) by Patricia Corcoran, documented the discovery of ‘new stone’ formed through intermingling of melted plastic, beach sediment, lava fragments and organic debris from Kamilo Beach on the island of Hawaii. Corcoran named it “plastiglomerate” and said it was distributed across the study site, and came to be through the melting of plastics from events such as campfires where the burning increased the density of plastic, inhibiting it from being transported by wind and water and increasing its potential for burial and subsequent preservation in the rock record.

Photo: Corcoran (2012) Photographs of plastic plastiglomerate on Kamilo Beach.

Photo: Corcoran (2012) Photographs of plastic plastiglomerate on Kamilo Beach.

Plastic trapped in the Arctic Ice

Humans produced nearly 300 million tons of plastic in 2012, but where does it all end up? A new study (June 2014 published in Earth’s Future) has found plastic debris trapped in the Arctic Sea ice. Rachel Obbard from Thayer School of Engineering, Dartmouth College, and colleagues have discovered that in remote locations of the Arctic Sea ice, there are concentrations of micro plastics at least two orders of magnitude greater than in other contaminated waters such as the Pacific Gyre discussed above. Their findings indicate that micro-plastics have accumulated far from population centres and that polar sea ice represents a major historic global sink of man-made particulates. The potential for substantial quantities of legacy micro-plastic contamination to be released to the ocean as the ice melts therefore needs to be evaluated, as do the physical and toxicological effects of plastics on marine life (Obbard et al. 2014).

If plastic (in its artificial synthetic form) was first developed in the early 1900’s, it has been around on the Earth for just over 100 years, and is already in waste quantities that it is impregnating itself in the fossil and ice record.

A snap shot of how plastic is affecting marine life

So let’s take a brief look into how plastics are impacting the larger of our marine life. in future articles I will delve into more detail on species specific trends, new research as it comes to hand and overall ecosystem impact (the out of site out of mind phenomenon). I will also interview several researchers that have spent their career documenting anthropogenic impacts on marine life.

“Plastic debris is a pervasive problem throughout the worlds oceans, and various governments worldwide have officially recognised the importance of managing this issue. In response, efforts to define, monitor and reduce the problem of plastic debris in the sea are increasing, especially as it poses significant risks to protected species.” (Australian Department of the Environment 2009).

A report was written in 2009 by the Australian Federal Government which compiled all available data on interactions between plastic debris and marine wildlife in Australian waters and provided a good summary on overall impact. Available information indicated that at least 77 species of marine wildlife found in Australian waters have been impacted by entanglement in, or ingestion of, plastic debris during the last three and a half decades (1974-2008). The affected species include

  • six species of marine turtles,
  • 12 species of cetaceans,
  • at least 34 species of seabirds,
  • dugongs,
  • six species of pinnipeds,
  • at least 10 species of sharks and rays, and
  • at least eight other species groups

Many of the animals listed above are known to ingest debris and is one of the leading causes of their deaths. Leading the way are sea turtles and seabirds. The debris item may be mistaken for food and ingested, an animal’s natural food (e.g. fish eggs) may be attached to the debris, or the debris item may have been ingested accidentally with other food. Debris ingestion may lead to loss of nutrition, internal injury, intestinal blockage, starvation, and even death.

Here are some images to get you thinking, as they say, a picture is worth a thousand words…

Till next time, think about where your rubbish ends up, how quickly it breaks down, and how long you are going to leave your plastic mark on the earth.

References


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