Invasive Species Are Becoming Increasingly More Common

Scientists from the University College London, collaborating with universities across the globe, have found that the number of invasive animal species is on the rise. In the past 200 years, the number of reported invasive species has shot up by about 37%. The findings are in a paper that was just published in the journal Nature Communications.

Invasive species are organisms that are not native to the environment they’re found in. They are generally introduced by humans, either intentionally or accidentally. Sometimes, animals are introduced to areas to control pests. In other cases, the invasive species hitchhike on boats and other vehicles. This has allowed invasive plants, animals, and microbes to travel across the globe. The problem is that these organisms often lack natural predators in their new ecosystems. They may outcompete or even hunt down the local, native species. For example, cane toads were introduced to Australia to help control pest populations that were decimating sugar cane fields. Although the toads were technically capable of eating these pests, sugar cane fields were not a great habitat for the amphibians, prompting them to leave in search of food elsewhere. They have no predators on the continent due to toxic glands and have tons of offspring at a time—allowing them to spread rapidly to the point of causing problems for local residents. Now, efforts are being made to reduce the number of these invasive toads. Researchers have previously reported on the current status of invasive species but there had yet to be a study on the actual rate of introductions.

Researchers from institutions throughout the world worked together on a massive project to analyze all available data on invasive species reports. In total, the team used data from studies of 16,926 invasive plants and animals. The research team found that the number of reports has steadily increased and then suddenly peaked in the 1990s. In 1996, at least one invasive species was reported each day. At least 37% of invasive species were reported within the last 200 years and there’s no sign of a slowdown.

The research team predicts that invasive species will continue to be introduced to new areas, even if inadvertently, and that current control efforts haven’t been enough. Since these non-native species can destroy local ecosystems, the researchers emphasize the need for better preventative plans.


Seebens et al. No saturation in the accumulation of alien species worldwide. Nature Communications (2017).

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