Invasive Species: Biggest Invisible Threat?

The world’s focus on major environmental issues has diverted attention from a significant threat. Time to wake up to it before it’s too late.

Photo courtesy: Unsplash

The article was originally published on WeNaturalists, as a part of the curated section by the editorial team. For similar stories, head to our Explore section.

It’s no secret that the raging environmental crisis has expanded to the extent that it threatens our survival as well as that of millions of other species. Climate change, biodiversity loss, environmental pollution, waste accumulation, deforestation, desertification, water scarcity, etc. — the threats our planet is facing are severe and growing. Let’s talk about one of the seemingly less discussed yet pertinent issues affecting the global community — the threat of invasive species. Also, we need to strategize measures for the conservation of ecology.

Why are invasive species so harmful to the environment? Incidents of invasive species competing with and eventually replacing native species have been recorded all over the world.

The invasive grey squirrel has almost completely eradicated the local red squirrel in the UK. Likewise, the introduction of rats and mice on South Georgia island in the southern Atlantic utterly destroyed the population of the Pipit bird.

The incidents of invasive species displacing the native species are not limited to animals. Even alien plant species are known to invade and replace the local ones. For example, a non-native species — the Devil Tree, has successfully conquered around 5.6 million hectares of land in India, 1.8 million in South Africa, 800,000 hectares in Ethiopia and around 600,000 in Kenya.

So, how serious of a threat does Invasive Alien Species (IAS) pose? A grave one.

  • According to a study published in the Biological Letters journal, since the year 1500, IAS are the second biggest reason for the extinction of species, which shows the magnitude of the threat.
  • Another study, conducted by an international team of researchers, found that an increase of IAS by 20–30 percent would be one of the key causes of global biodiversity loss, around the world.
  • The National Wildlife Federation (US) estimates that around 42 percent of the threatened and untreated endangered species are facing risks because of IAS.
  • Based on the ever-growing relocation of IAS worldwide, a study commissioned in 2020 calculated that there will be a rise of 36 percent in the number of confirmed alien species from 2005 to 2050.
  • The killing of native species and keystone species by IAS also causes the spread of diseases. The arrival from North America of the invasive signal crayfish brought the crayfish plague along with it, which resulted in the en masse killing of the white-clawed crayfish native to the UK.

Impact of Invasive Species on the Ecosystem and Economy

Photo courtesy: Wikimedia Commons

While studying the invasive species’ threat to biodiversity, we see that the arrival of a foreign species disturbs the delicate ecological balance. In the absence of predators, invasive species breed and spread quickly, covering a large area and changing its biodiversity.

Among many issues, this affects the food web of the ecosystem as native species lose their habitats and traditional food sources. The loss of biodiversity also weakens the resilience of the ecosystem and makes it more vulnerable to forest fires and climate change. Moreover, they also affect keystone species.

Some aggressive plant species can, in a short period, make it a monoculture. Also, the spread of some IAS can change the natural conditions, like lowering soil health and increasing the intensity of forest fires.

Invasive insects alone cost over $70 billion to the global economy each year. Invasive plants and animals are responsible for causing losses worth $137 billion in the US and $33.5 billion in Southeast Asia every year.

Reduced agricultural production remains the biggest impact of invasive species, affecting food security and the global economy.

  • For instance, the invasive species Parthenium hysterophorus caused the yield of sorghum in Ethiopia to drop by 82–95 percent.
  • Another invasive plant species, the Lantana Camara, affected over 13 million hectares of pastureland in India and poisoned about 1,500 cattle in Australia, leading to a loss of pasturelands and reduced output.
  • In Nigeria, the spread of the alien insect — Tomato Leafminer — massively damaged tomato production, forcing a $200 million tomato factory closure.
  • The presence of four invasive species led to the loss of 83 percent of coffee plantations in the East Java province of Indonesia.

Measures to Tackle this Invisible Threat — Protection of Biodiversity

Photo courtesy: Wikimedia Commons

With a lack of sufficient information about the behavior and effects of IAS on natural ecosystems, the measures to control them are limited in their effectiveness. As their threat’s been established, the need for further research is essential.

Additionally, the spread of IAS across geographical boundaries entails the need to focus on the most susceptible countries, most of which rely on subsistence farming and lack the resources to control such species.

Along with that, the links between invasive species and climate change mean that policies made to address climate change must also include measures for controlling and preventing their spread. And wherever possible, the measures that address both the issues simultaneously should be prioritized to minimize the impacts. International cooperation in identifying and eliminating alien species before they become invasive can go a long way in addressing the challenges faced in tackling climate change and the protection and preservation of ecological balance.

Shrinking habitats, rising sea temperatures, overgrazing, etc. and other issues arising and causing the nature crisis due to human-led activities is cause for concern. It’s giving an impetus to problems like invasive alien species that invade and destroy the natural world. Taking cognizance of every problem — small and big — is essential. There’s no time to deliberate. The time for Climate Action is now.

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