Written by Victoria Liptakova - Editor: Anastasia Eginoglou
Some living organisms can suddenly appear in habitats that are unnatural to them and cause harm to native creatures. They tend to reproduce fast, and if thriving, harm not just the natural balance in the invaded area but also the economy and overall health of humans by spreading diseases or causing allergies. Such invasions happen mostly unintentionally, although in some cases, a direct activity can be a reason too. Proper examples could be the release of pets free or species unintentionally carried on transit boats.
Statistics show that invasive species contribute to extinctions and threaten more than 40% of endangered species around the world. They have already exterminated 16% of endangered organisms with no other contributors in play. Additionally, they can change soil conditions, bring diseases or intensify wildfires. Some are well-known, like rats, but invasive species are not only animals; they could be fungi or even plants - for instance, a plant called kudzu is capable of destroying an entire diverse ecosystem alone. Climate change only supports invasive species in their endeavours, and fighting against it consumes billions of dollars globally. This all has a massive impact on communities that depend on nature and its resources to live, like Indigenous people. Unfortunately, many researchers expect this problem to continue and only grow in the future.
Amphibians are organisms that can live both on land and in water. First noticed in the 1980s, biologists discovered a horror-like fungus spreading all around the planet, killing amphibians. If infected with the fungus, their skin hardens, making them unable to absorb needed water. Approximately five hundred species have drastically declined in numbers, and it is stated that ninety of them are already permanently gone. The most endangered areas are South and Central America, together with Australia. Researchers have considered this fungus as probably the most aggressive of invasive species ever recorded. However, not everything is lost yet. Sixty species have shown a certain adaptation to the fungus and evolved into more resilient organisms. It is indeed great news, but scientists warn that global warming, weather extremes and pollution could overthrow this adjustment and eventually help the fungus to kill.
Salamanders have been facing a similar fungus with a mortality rate of almost 100 per cent. Once infected, it takes just a few short days before their unfortunate death. This fungus has been noticed in Europe, first in the Netherlands and later in Belgium, Germany and Britain. Scientists have conducted numerous tests to identify which kinds of salamanders are more resistant and how they could protect the weaker ones. This disease affects their skin and causes necrosis, while spotted salamanders are immune; the existence of fire salamanders is at stake.
Lionfish can usually be found in the South Pacific and Indian Ocean, but suddenly, this invasive species was also spotted in Florida. It is believed that escapes and releases from local aquariums are the prime cause. Lionfish live in tropical waters and therefore quickly spread from the United States to the Caribbean. They are a danger to native coral ecosystems and a potential risk to other natural ecosystems such as wetlands and water creeks. They are predators and consume mostly smaller fish and important herbivores, which often care for the well-being of corals. With no predators around, lionfish can thrive and overpopulate the area, which could eventually negatively affect fishing by leaving only lionfish around to catch. Back in 2014, it was presented that the situation had been under control, yet regulating practices should be continuously encouraged further.
Another unpleasant appearance happened in Alaska, where the presence of green crabs was confirmed. These crabs are strong, highly competitive predators and can easily overtake the territory of other crabs, harm shellfish, even salmon and diminish certain habitats. Originally, they came from the western and northern parts of Europe. Local biologists have therefore been mapping the area and managed to survey typical places for base colonies of this in-Alaska-banned species. However, they still ask civilians for help reporting any sightings of the creatures as they can be easily recognised by five spikes growing next to each other on their sides.
Australia is rather isolated, which makes its invasive species slightly more complicated to fight. With not many predators present, harmful organisms spread quickly across the continent. Even the wild dog dingo, one of the main Australian predators, is currently in danger of being hunted by humans. Australia has therefore introduced a disease virus aimed at wild rabbits as they have been dramatically destroying crops worth 1150 million dollars yearly. Animals once used for transportation, kept as pets, or introduced to Australia as predators are now being targeted to reduce their populations and minimize their negative impact on ecosystems. These have been fought by poisons, viruses or limited with fences. However, some solutions did not work in the past and do not work even today - back in 1935, beetle-eating toads were supposed to help with the problem of bugs eating sugarcane plants. But these toads were not able to reach the height of bugs munching on the plants, and as of today, nothing has changed.
As with any climate issue, knowledge and advocacy are critical tools for lasting effects. Policies should accept safe over easier solutions when combating climate problems. They should also include guidelines on what could happen if improper measures, with invasive species in mind, were adopted. Effective information flow and monitoring should take place in areas where such species have been noticed. Additionally, educated predictions could help in handling various possible scenarios in the future. Stricter border controls for carrying vehicles and imported goods could work as a great prevention. Collaboration with Indigenous people and local communities could bring many benefits as well. High biosecurity, cooperation of responsible institutes and a prompt answer to spotted threats are key. Because of that, resources need to be well-delegated in order to support such actions. Of course, individual efforts are also important to mention. As individuals, we can plant more native plants where we live, check our boats, car tires, and boots more often, and remove any invasive species that are spotted. Many situation-overlooking organisations have already published guides on how to help and what to do if invasive species are discovered in nature by people. Whoever would like to contribute personally can follow them.
Sources:
National Wildlife Federation. (2019). Invasive Species | National Wildlife Federation. [online] Available at: https://www.nwf.org/Educational-Resources/Wildlife-Guide/Threats-to-Wildlife/Invasive-Species.
Biosafety Unit (2024). What’s the Problem? [online] Cbd.int. Available at: https://www.cbd.int/invasive/problem.
Pappas, S. (n.d.). Amphibian-Killing Invasive Fungus Causes Record Wildlife Loss. [online] Scientific American. Available at: https://www.scientificamerican.com/article/amphibian-killing-invasive-fungus-causes-record-wildlife-loss/.
Crane, B. (2017). U.S. Salamanders Threatened by Deadly Fungus. [online] Scientific American. Available at: https://www.scientificamerican.com/article/u-s-salamanders-threatened-by-deadly-fungus/.
NOAA Fisheries (2022). Impacts of Invasive Lionfish. [online] NOAA. Available at: https://www.fisheries.noaa.gov/southeast/ecosystems/impacts-invasive-lionfish.
NOAA Fisheries (2022). Look out for Invasive Crab! | NOAA Fisheries. [online] NOAA. Available at: https://www.fisheries.noaa.gov/alaska/habitat-conservation/look-out-invasive-crab.
Fisheries, N. (2022). Green Crab Detected in Alaska for the First Time | NOAA Fisheries. [online] NOAA. Available at: https://www.fisheries.noaa.gov/feature-story/green-crab-detected-alaska-first-time.
Biba, E. (2017). Inside Australia’s War on Invasive Species. [online] Scientific American. Available at: https://www.scientificamerican.com/article/inside-australia-rsquo-s-war-on-invasive-species/.
iucn.org. (2021). Invasive alien species and climate change. [online] Available at: https://iucn.org/resources/issues-brief/invasive-alien-species-and-climate-change.