Invasive Species – A Global Threat Behind Biodiversity Loss

Report by the UN’s Intergovernmental Platform on Biodiversity and Ecosystem Services Highlights Invasive Species as a Threat Behind 60% of Recorded Biodiversity Loss

By Orkhan Huseynli

The report by the UN’s Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) highlights the growing concern regarding invasive alien species and their detrimental effects on ecosystems, food security, and livelihoods worldwide.

The Assessment Report on Invasive Alien Species and their Control, conducted by a team of 86 researchers from 49 different countries over a four-year period, underscores that the threat posed by alien species is likely to increase in the coming years, with more than 37,000 species being introduced around the world by human activity and 3,500 of them being invasive.

If current trends continue, with 200 new alien species being recorded every year, there could be a 36% increase in global alien species numbers by 2050, compared to 2005. The fact that approximately 60% of recorded biodiversity loss is attributed to invasive species underscores their severe impact on global biodiversity. This statistic highlights the role that invasive species play in driving native species to extinction, often by outcompeting them for resources, introducing new diseases, or disrupting local ecosystems.

The situation demands urgent and effective measures to manage and mitigate the spread and impact of invasive species in order to protect the world’s native flora and fauna.

Invasive Species: A Leading Driver of Biodiversity Loss

The northern snakehead (Channa argus) is a striking example of an invasive species that has garnered attention due to its successful establishment in North American waters.
By Brian Gratwicke – Snakehead – Channa argus, CC BY 2.0

Invasive species are non-native organisms that cause damage to crops, wildlife, and human health by entering ecosystems where they don’t naturally belong. They can harm native species through predation, competition for resources, or disease transmission.

Invasive species are introduced to new areas either accidentally or intentionally by humans, being transported through trade, travel, cargo, or ballast water on ships.

According to the researches, among alien species, approximately 6% of plants are reported to become invasive, while this figure is 14% for vertebrates, 22% for invertebrates, and 11% for microorganisms. It’s crucial to recognize that not all alien species transform into invasive ones.

For instance, tomato plants, originally cultivated in the Andes mountains, aren’t typically considered invasive. However, in cases where plants or animals, whether in marine or terrestrial environments, lack natural predators, they can multiply unchecked.

The statement from IPBES that invasive species are one of the five key sources of biodiversity loss highlights the significant role these species play in driving ecological change and threatening native ecosystems. “Invasive alien species have been a major factor in 60%, and the only driver in 16%, of global animal and plant extinctions that we have recorded, and at least 218 invasive alien species have been responsible for more than 1,200 local extinctions,” stated Prof. Anibal Pauchard, a co-chairperson of the assessment, in a press release.

The IPBES report indicates that 34% of the effects of biological invasions were reported from the Americas, 31% from Europe and Central Asia, 25% from Asia and the Pacific, and about 7% from Africa.

Invasive species have a disproportionate impact on islands, where they can lead to significant ecological disruptions. For example, on more than 25% of all islands, the number of alien plants now exceeds the number of native plants.

Small islands housing unique species found nowhere else on the planet are particularly susceptible to threats. The report statistic reveals that around 75% of the negative impacts occur on land, particularly in forests, woodlands, and farmland, which underscores the significance of terrestrial ecosystems in the context of invasive species.

Over 2,300 of them have been identified within the territories managed by indigenous communities, potentially impacting their quality of life and cultural identity.

The zebra mussel (Dreissena polymorpha)
The zebra mussel (Dreissena polymorpha)
By Smithsonian Environmental Research Center – Dreissena polymorpha_(I1957)_0265, CC BY 2.0

Origins and Profound Effects

The report identifies the black rat as the most prevalent invasive animal species, and its spread is attributed to its ability to hitch a ride on ships.

This adaptable creature has successfully infiltrated not only densely populated urban areas but also remote islands, where its presence has had devastating consequences for local ecosystems.

The consequences of invasive rats extend beyond direct predation. Their activities, such as burrowing and foraging, can lead to soil erosion and vegetation damage on islands. These changes in land structure can, in turn, affect the flow of nutrients into the surrounding ocean waters. Even nearby coral reefs and reef fish can experience the repercussions of altered nutrient dynamics, underscoring the interconnectedness of terrestrial and marine ecosystems.

The northern snakehead (Channa argus) is another striking example of an invasive species that has garnered attention due to its successful establishment in North American waters.

Originally native to regions in Asia, this fish has become an invasive species in North America, particularly in the United States.

The northern snakehead is known for its unique characteristics, including its ability to breathe air, which allows it to survive in a variety of aquatic environments. This adaptability has contributed to its success as an invasive species. It can tolerate low-oxygen conditions and has a voracious appetite, feeding on a wide range of aquatic organisms, including fish, amphibians, and crustaceans.

One of the most notable aspects of the northern snakehead invasion is its potential impact on native ecosystems. As an apex predator in its new habitat, it can disrupt local food webs and outcompete native species for resources. This can lead to declines in native fish populations and other aquatic organisms, affecting the overall health of aquatic ecosystems.

Efforts to control and manage the northern snakehead’s spread have been challenging due to its resilience and versatility.

Invasive species often have intriguing and complex origins, with some of them being directly linked to activities such as wildlife trade and global commerce.

One compelling example is the case of the zebra mussel (Dreissena polymorpha), which has had a profound impact on non-native aquatic ecosystems. Zebra mussels are small, freshwater mollusks native to Eastern Europe and Western Russia. They gained notoriety for their invasive spread in North America, particularly in the Great Lakes region. The precise arrival of zebra mussels in North America is suggested to have occurred in the 1980s, likely through European cargo ships.

The once-dominant hyacinth (Eichhornia crassipes), which blanketed nearly 90% of Lake Victoria’s surface, had disastrous consequences, including hindering transportation and fishing, suffocating aquatic ecosystems, obstructing hydroelectric dam intakes, and fostering mosquito breeding grounds. This invasive plant is believed to have been introduced into the region by Belgian colonial authorities in Rwanda, initially as an ornamental garden flower. Its subsequent journey downstream through the Kagera River in the 1980s triggered a widespread environmental crisis.

The cane toad (Rhinella marina)
The cane toad (Rhinella marina)
By Bidgee – Own work, CC BY 3.0

Impacts on Economies and Ecosystems

The economic costs associated with invasive species are substantial. They can harm industries such as agriculture, fisheries, and tourism, leading to financial losses and reduced livelihoods.

Invasive pests can damage crops, reducing yields and increasing production costs. Aquatic invasive species can disrupt fisheries, impacting both commercial and recreational fishing. Also, they are able to affect tourism by damaging natural landscapes and reducing the appeal of natural areas.

As per the report’s findings, the collective economic burden linked to invasive species currently stands at a minimum of $423 billion every year, having at least quadrupled every decade since 1970, including expenses related to managing and mitigating the impacts of invasive species on agriculture, infrastructure, and natural resources.

Scientists underscore the pervasive proliferation of invasive species as a compelling testament to the profound transformation of natural ecosystems resulting from the rapid expansion of human activities, heralding the advent of the Anthropocene epoch, often dubbed the “age of humans.”

A landmark global treaty for biodiversity conservation, negotiated in Montreal last December, establishes a goal of halving the rate of spread of invasive alien species by the year 2030. While the IPBES report delineates comprehensive strategies for this mission, it abstains from assessing the likelihood of its realization.

The assessment report primarily establishes three key approaches: prevention, eradication, and, as a last resort, containment. Efforts to eradicate invasive species have typically faced challenges, particularly in extensive bodies of water and open water channels, as well as in vast, connected land areas.

Surprisingly, the locations that have achieved the highest success rates in eliminating unwanted invasive species, particularly vertebrates like rats, are also the ones that have been the most vulnerable — small islands.

About the Author

Orkhan Huseynli is a freelance science and environmental writer. His academic journey has encompassed fields such as Public Administration, Management, and Economics, culminating in a master’s degree in Environmental Economics and a Ph.D. specialization in Industrial Management.

Orkhan Huseynli

Transitioning from a career in IT, Orkhan is now dedicated to pursuing his passion for science and popular science writing. Orkhan is keen to contribute his writing skills to the world of articles and essays, covering topics like Climate Change, Biodiversity, Environmental Economics, Ecology, Paleoscience, and Environmental Politics.

For him, the prospect of writing for scientific outlets represents a chance to share his knowledge and raise awareness about crucial scientific advancements, fulfilling his aspiration to engage with a broader readership.

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