Plastic Harms the Ecosystem
Plastics can cause harm to wildlife through ingestion, entanglement and toxicological influence. Wildlife may mistakenly ingest plastic debris as they feed, or ingest them through the food chain. Planktons are the essential foundation of the marine food web. Many plankton feeders are known to consume plastic as they mix them with their food. They then pass the ingested plastic to predators. Scientists detected a high plastic to plankton mass rate in the surface waters of the North Pacific Central Gyre, which is an indication of how serious the problem could be worldwide. Predators at higher trophic levels can also ingest larger and more dangerous debris directly. You may have heard of cases of turtles and whales dying of plastic ingestion. The photos and videos below show sea turtles and dolphins eating or playing with floating plastic bags that resemble their natural diet, jellyfish.
Jellyfish or Plastic Bag?
Once plastic debris enters the animal’s gut, it may cause a blockage, perforation of the intestines and buoyancy problems. Even if the animal continues foraging, the reduced gut volume can lead to malnutrition and health problems, and ultimately threaten their life.
Opposite: Video of a straw being pulled out of a sea turtle's nose.
Impact on Wildlife
Plastics ingestion also has toxicological impacts on animals. Some chemicals in plastic debris are poisonous. Pollutants in seawater can concentrate in plastic or harmful additives may already be present in plastic. Furthermore, microplastics, carrying chemicals of small molecular size (MW<1000) can penetrate cells, enter the circular system and affect the endocrine system of animals.
Entanglement is another concern. Fishing nets and other plastic waste can entangle animals. Once entangled, species such as seals are unlikely to escape without external help, and the animal may then die of “starvation, strangulation, wounds and infection, dehydration, drowning, increased vulnerability to predation, or combined effects”.
To what extent are marine animals exposed to the threat of plastics? A review shows that plastic ingestion or entanglement cases have almost doubled between 1997 and 2015, with 557 species affected. This includes fish, seabirds, invertebrates, marine mammals and sea turtles. Scientists concluded that both the plastic ingestion rate of individuals and the number of new species known to ingest plastics are increasing. They predicted that by 2050, plastic debris will have been found in 99% of seabird species, and within these species, 95% of individuals will have ingested plastics. Detailed studies on mortality rate could not be conducted on every species due to the vastness of the ocean environment and the rarity of onshore carcasses. Right now, ocean plastic could be harming our fragile marine eco-system and threatening critically endangered species. Fighting ocean plastic is more than the welfare of a single turtle or dolphin. It is about saving the entire marine ecosystem.
Research by Sustainability Office Intern Bingo Xu 2018