Plastic and Environment

© N.Pansiot/Tara Expeditions. Echantillons plastique

With millions of tons of plastics dumped into the oceans each year, the environmental impacts are numerous and lasting. While the dangers for certain species, such as turtles, are known to the general public, the plastic could cause other less obvious damage.

According to some associations, plastic wastes are responsible for the death of 100,000 marine mammals and one million birds each year. These estimates are, however, difficult to verify. First of all, it is highly likely that some animal victims of plastic waste end up at the bottom of the ocean rather than washing up on beaches, making them difficult to count. On the other hand, the mere fact of finding plastic in the stomach of a dead animal does not necessarily mean that it was the cause of death. While exact numbers are difficult to estimate, it is still certain that plastic waste is causing significant damage to marine fauna.

The most striking example is probably that of turtles mistaking plastic packaging with jellyfish, their favorite food. Some end up dying of intestinal obstruction or choking. One turtle was found with more than 2 kilos of plastic in its stomach. For seabirds, the situation is no less alarming. A recent study found that in the Mediterranean, of 171 birds captured, two-thirds had at least one plastic debris in the stomach. For some species, such as Cory’s shearwater, the figure is even higher: 94% of the birds had swallowed plastic, with the potential risk, as with turtles, of choking or intestinal obstruction. In addition to these dangers, some plastic waste, such as abandoned synthetic nets, wreak havoc by trapping many marine species, leading to their starvation or strangulation.

According to recent studies, more than 600 species are affected by seawater pollution. Obviously we think of the larger animals – turtles, whales and seals – but in fact the whole food chain is interacting with plastic. Besides the most visible waste, tiny plastic particles called microplastic can also be ingested by small fish and some plankton species. Impact studies are still too few to assess the threats posed by these microplastics on the first link in the food chain, but the question of toxicity for these organisms can be posed. There are indeed many types of plastic materials using various compounds, some of which are particularly harmful to the environment and are now banned, but are still found as waste in the oceans.

In addition, some plastic materials have the unfortunate ability to absorb pollutants (pesticides, hydrocarbons, etc.) present in sea water. Ingested by small marine organisms, these toxic chemical “sponges” again pose the question of risks for these organisms and the rest of the food chain. Though ingested toxic concentrations  appear minimal for now, further research must still be carried out, particularly for planktonic species. Finally, plastic waste harbors species that move with the currents. A few months after the 2011 tsunami carried huge amounts of trash into the sea, over 100 new species arrived on Canadian shores, clinging to floating debris. The arrival of invasive species that disrupt local ecosystems, and of pathogenic micro-organisms, could potentially lead to major environmental disasters. Since removal of ocean plastic waste is not an option, understanding the phenomenon and its impact on the environment through new studies such as those conducted on Tara, is therefore essential.

 

Yann Chavance

 

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