In this blog, I am going to give some examples of human-introduced invasive species, and the harms they have on their new environments. There are constantly new invasive species that explore different ecosystems because of climate shifts or strong storms or simply because animals are trying to escape overcrowded areas. But the species introduced by humans are the most harmful because organisms run rampant in ecosystems they would have never been able to get to without humans. They have no predators in these new places, allowing them to throw the whole ecosystem out of whack.
Believe it or not, rabbits have had a terrible impact on the land down under. Australia has had a problem with European rabbits since their introduction to the continent in the late 19th century. Now, it is estimated that approximately 200 million feral rabbits inhabit Australia. In 1859, Thomas Austin, a wealthy settler who lived in Victoria, Australia, got 13 European rabbits, so he could hunt them. He let them roam free on his estate, but they eventually escaped into the wild. From this one backyard sanctuary, it took only around 50 years for these invasive rabbits to spread across the entire continent. Their numbers became so large that they destroyed crops and land, leading to soil erosion. They also negatively affected agriculture and plants by overgrazing, and they contributed to the decline of native plant and animal species. In some areas, the rabbits ate so many plants that they began dying of starvation because they had exhausted their food supply. The Australian government has taken action to try and stop the growth of the rabbit population, but the problem is still way out of hand.
Kudzu is a plant native to Eastern Asia and some Pacific Islands that was introduced to the southern plantations of America in 1876. It was used for animal feed and as a porch decoration for the elaborate mansions. Kudzu is an aggressive vine, capable of growing up to 26 centimeters per day. Since it expands so quickly, it smothers other plants, stopping them from having access to sunlight. Kudzu can even kill mature trees. What’s even worse is that once kudzu starts growing, it is extremely difficult to get rid of. In the South, the kudzu took over huge swaths of land killing everything in its wake, which is what gave it the nickname “the vine that ate the South.”
Zebra muscles have also had some terrible impacts on ecosystems across the globe. Native to the Black, Caspian, Aral, and Azov Seas, these organisms have wreaked havoc throughout Russia, Europe, and North America. Zebra mussels traveled around the world in the ballast water of ships (water carried by ships to help them stay balanced while at sea) and by attaching themselves to the outsides of boats. Zebra mussels are a problem because their population numbers grow incredibly quickly, making them one of the most aggressive freshwater invaders. Massive populations of zebra mussels filtering water can severely impact the native plankton populations, which reduces food for fish. These plankton-eating fish then have to find a new source of food or move to new areas in order to survive, making them an invasive species. Unfortunately, that isn’t an option for many species, so they die out. Zebra mussels also leave very little for native mussels to filter, causing them to starve as well. Zebra muscles were first discovered in the Great Lakes in the 1980s, and along with the problems listed above, they have destroyed boat engines, fouled beaches, and caused damage to boat ramps and docks. Since they adhere to all hard surfaces, they also stick to the shells of native mussels, turtles, and crustaceans, severely harming them.
We have the power to stop the spread of human-introduced invasive species. More and more is being done to prevent more scenarios like those mentioned above, but in our connected world, it is a lot of work. But we have to maintain biodiversity and do everything we can to protect our planet so that it continues to protect us.