Oceans: the effects of plastics on animals and the environment

The first effect of plastic waste is a visual impact: debris washed up on the banks of rivers, beaches, piles of floating objects at sea. But some less directly apparent effects are also more severe.

Every second, hundreds of tons of waste (out of the 4 billion generated annually) ends up at sea, much of it plastic. Floating objects or microparticles, this plastic waste is deposited on beaches, dispersed at sea and found on the seabed. What effects do they have on man and his environment?

Highly resistant, abandoned or accidentally lost nets constitute a significant cause of mortality in animals; associations estimate that 100,000 marine mammals and one million birds die from strangulation or choking in these traps around the world each year. 

Transport of invasive species via plastic

Not many studies have been conducted, but the risk is there, with its environmental, health and economic consequences (invasive algae, bacteria in oyster or fish farming areas).
The recent discovery of the insect Halobates sericeus living on floating plastics in the Pacific is a perfect illustration. A 2007 study showed that the spread of species in subtropical waters has almost doubled due to debris. It tripled in temperate waters.

The real danger is the alteration of ecosystem balance caused by the transport of invasive species over long distances. Some wastes are useful floating supports for bacteria (specific pathogens for marine organisms such as humans, vibrios for example), unicellular or invertebrates, worms, insects, capable of acclimatizing in an area other than their original biotope, especially concerning climate change 

Ingestion of plastic waste by animals

The ingestion of plastic waste is another cause of mortality, affecting about 660 species. Seabirds sting floating pieces of plastic, and turtles confuse them with jellyfish.

Due to their components (plasticizers, additives) and the possible release of adsorbed contaminants, plastics are also suspected to be a source of water contamination. But in reality, the measured concentrations are too low for the substances released during their degradation to constitute a significant toxicity risk. The level of chemical contaminants remains limited but more dangerous for the filtering of marine organisms that accumulate them.

Large whales filter seawater, ingesting large quantities of microplastics. Molluscs, such as mussels, filter m3 of water containing microparticles. Plankton, invertebrates or small fish can also ingest Microwaste. However, the rate of ingestion remains very anecdotal for the species consumed (less than 0.01% of commercial fish), and there is no trace of it on our plates. Although micro waste can block the digestive and respiratory systems of some individuals, it is not digested due to the lack of suitable enzymatic equipment.