Tuesday, 17 September 2019

Plastic on the green menu

Updated: March 23, 2019 9:41 am

Plastic or non-biodegradable waste can prove to be highly fatal for terrestrial or land-based ecosystems as well as marine ones. While the impacts of non-biodegradable waste or plastic waste on the marine ecosystems have been extensively researched, its impact on terrestrial ecosystems is still poorly known.

Garbage dumps are getting ubiquitous in India

The gradual expansion and encroachment of human settlements in land and forests have resulted in the rapid spread of degradable and non-biodegradable wastes resulting in mounting garbage dumps and landfills in and around natural habitats. These areas attract wild animals, birds that feast on food acquired at garbage sites that are often strewn with plastic.

Studies show that wild animals can get used to feeding on garbage dumps regularly due to ease of availability that can alter their regular movement patterns, their eating habits and food utilisation patterns, impact their social behaviour and can increase the risk of human–animal conflicts and of disease transmission due to interaction of domestic and wild species at garbage dumps.

Plastic can be  lethal for animals

Studies show that animals can accidently ingest plastic which can lead to lethal injuries and blockages in their digestive system leading to starvation, ulceration or perforation of the digestive tract. Animals can get caught in plastic leading to injuries and abrasions, impaired movement and feeding, reduced fitness, growth problems and premature death. Chemicals from plastic can be toxic and have a negative effect on the reproductive and neurological systems of animals and cause abnormal hormonal functioning.

While a number of instances have been reported on how animals like red fox, grizzly and black bears, Asian elephants demonstrate altered food habits due to garbage near human settlements and fringes of forests, very few studies have looked at the impact of garbage and ingestion of plastic on wild and terrestrial animals in India.

The plastic  menace in natural  reserves of Uttarakhand

The Himalayan state of Uttarakhand in North India has over 45 percent forest cover and gets more than 20 million tourists per year who frequently visit the nature reserves in the state. This ever-expanding tourism has taken a toll on the environment in the state and has led to increasing generation and disposal of degradable as well as non-biodegradable wastes near these reserves and forests. However, little is known of the impact and interaction of waste with wildlife in the area.

This paper titled Trash on the menu: patterns of animal visitation and foraging behaviour at garbage dumps from the journal Current Science presents the findings of a study that looked at animal feeding behaviour at garbage dumps located along the edge of a mixed forest dominated by oak, pine and rhododendron trees from a village in the Nainital district. The forest is a conserved area and is inhabited by more than 200 bird species and 75 mammalian species.

Two garbage dumping sites, one that was made up of unsegregated non-biodegradable waste and another made up of a compost pit that consisted of organic food waste were selected for the study and animal foraging behaviour and the risk of plastic ingestion by different species were observed.

Wild animals feasted on garbage The study found that:

  • Wild animals loved garbage and frequently visited garbage sites. They could be classified into three categories based on their feeding behaviour.
  • Peckers: Animals with beaks which pulled out food from plastic and other inedible waste. This included birds which dug through garbage to access insects, worms or edible food waste.
  • Handlers: Animals with dexterous hand appendages that were capable of separating food from other waste. This included mainly monkeys who removed food from inedible packaging using their hands.
  • Gulpers: Animals that lacked dexterous hand or mouthparts and could not separate food from plastic and other indigestible matter before ingestion. This included animals like cows, buffaloes, elephants, dogs, cats, wolves etc, who had limited ability to separate food from plastic and frequently swallowed indigestible matter along with edible waste.
  • Plastic was the most common non-biodegradable waste that was handled or processed by animals. Other materials such as glass and metal were rarely handled by the animals.
  • Thirty-two different species of animals frequented the garbage sites to feed on garbage. More animal species were found at the larger waste site that included non-biodegradable waste.
  • The proportion of wild animals visiting garbage dumps was observed to be over five times higher than domestic animals.
  • Animals that usually feed during night and twilight frequented the larger garbage site that included non-biodegradable material.
  • Animals spent approximately two to four minutes at the garbage dump sites.
  • Handlers and peckers encountered plastic more than twice as frequently as gulpers. However, gulpers such as deer, civets and martens were observed to be feeding more frequently and spending longer duration near the garbage as compared to handlers and peckers. This increased their risk of ingesting plastic as they were unable to separate plastic.

Plastic remains have been frequently reported from the stomach contents and faeces of gulpers including mammals such as red fox and elephants as well as birds with large beaks such as storks and vultures.

The study identifies the urgent need to tackle the waste crisis invading natural reserves in places such as Uttarakhand where wildlife is at constant risk of being exposed to and ingesting plastic. It suggests that:

  • Reserve managers should be involved in formulating and implementing policies for solid waste managementin and around reserves.
  • More studies should be undertaken to get a better understanding of the scale of impact of plastic and non-biodegradable waste on animals
  • There is a need for creating public awareness on waste segregation and discouraging use of disposable plastics along with undertaking preventive measures such as fencing garbage dumps and landfills and shifting garbage dumps away from the forests.

(indiawaterportal.org)

By Gitanjali Katlam Et Al

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