NOTE: i am in no way saying carrying invasive species around isn’t bad/harmful! it very much is a big issue. i am just a bit lost on how humans (being animals) are doing “incorrect” unnatural things since we are natural(compared to other living things who don’t necessarily harm their environment)
okay, so i don’t really understand the whole invasive species thing. when humans carry plants/animals to different regions and they start rapidly growing there, why do we need to get rid of them? humans are animals as well (great apes), and a way that seeds/eggs spread is by grabbing onto other animals as they travel. so why is it different when people do it? i’m just confused
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An invasive species is typically something that is not native to an area. It can grow and take over local foliage, which in turn depletes the food for local animals.
Let’s say I introduce some new fish to a lake, fish A,, these fish reproduce and grow much faster than the native fish, fish B, as a result they eat a lot of the food and most of fish B die out, the local predator fish, Fish C, expand in numbers due to the abundance of Fish A to eat.
Then Fish A start to die out as they’ve eaten to much of the food supply, this is sped up by Fish C who also eat the last of fish B.
Now we have a lack with no fish left.
That’s the danger of invasive species.
We don’t naturally carry them the way seeds spread on plant fur. We straight up yoink them!
Its also bad because it upsets the local environment, can potentially kill off a vital food source causing chain reactions down the food chain.
In nature, animals (not humans) have a limited range they can spread seeds to n their droppings and from fur. It generally will only spread a species within an area it is “ok” to exist as their are natural predators or other factors such as weather that will keep it in check.
Humans, on the other hand, have none of these limitations. A tropical plant can be brought to Alaska and a wild snake from Asia to Florida.
I will use the pythons as an example. Humans brought pythons to the US for “pets”. Once they were too big or there were reasons to not ditch them, irresponsible humans released them into the wild. The Florida Everglades is a great match to their habitat- but there are several things missing. There are no apex predators to the snakes. The only animals big enough and capable enough to eat them are humans, some gators, and the near extinct panthers. So the snakes reproduce at breakneck speed and eat everything that fits in their gullet. Small rodents, raccoons (nearly wiped out now), birds, deer, and even the apex predators once though able to keep the pythons in check.
Because they have no predators able to control the population, they are eating the available supply of food faster than it can reproduce. This steals food from other animals which also need to eat. So it is a twofold strain. No predators means more snakes, and more snakes means less food for every animal.
With plants, it works in the same way, except with plants, it is a “who can grow faster and choke out a native plant”. Dirt and square feet are food sources that are competed for. Wild Mustard is a horrid invasive species in my area. It is more resilient, faster growing, and it’s roots choke out those of other native plants. There are no animals (besides some livestock) that eat it naturally and no weed killer to selectively kill only wild mustard. The main way of killing it is by ripping it out manually, one plant at a time.
Once the balance of the food chain is disrupted, every living thing in it is affected.
It’s not so much about the spread of certain species, it’s about the potential harm that they can cause to other wildlife. It’s more like how humans are typically prohibited from hunting endangered animals to protect their existence, not so much about them reproducing in certain areas. Invasive species can cause unexpected damage to other wildlife that previously did not have to experience it.
Because those invasive species can destroy the biodiversity of that ecosystem they are placed in. For example, the Burmese python is a very invasive species in the Florida Everglades and they reproduce very quickly. So every year there is a snake hunting season where trained people go out and catch as many snakes as they can for money. These snakes eat up everything in those places including rats, raccoons, deer, etc. They are a major problem for that ecosystem.
Ok, the thing to recognize is that you cannot treat the activity of humans as that of just yet another animal. We are uniquely powerful and effect change on a scale and speed utterly unprecedented in nature. We are uniquely powerful, and thus uniquely responsible. It makes sense to differentiate the activities of humans from those of the rest of the animal world. Yes, we’re domesticated apes, but we’re _special_ domesticated apes.
There are some great real-life examples to explain this:
When the British first came to New Zealand, they brought rabbits with them as a cheap food source. However, the rabbits bred faster than the humans could hunt them, and were no other predators big enough to kill a rabbit, so their population exploded.
The huge rabbit population ate the local plant life and food crops faster than they could regrow. The British decided to bring in stoats (a relative of the weasel) to hunt the rabbits and solve this problem.
However, New Zealand had a lot of native flightless birds that evolved without any major predators, and thus had no real defenses. The stoats realized that these birds were way easier prey than the rabbits, and preferentially hunted them instead. Several species went extinct as a result, and the rabbits remained a problem.
Bottom line is that if you introduce a species that 1.) can eat whatever already lives there and 2.) nothing already living there can eat it, it will cause havoc and breed out of control.
Our ability to carry many many different species very very quickly by air and boat every day disrupts that more natural adaptation of wildlife
A lot of people have given some very good examples of how invasive species can lead to a loss of biodiversity. One thing that also plays a part in why we control invasive species is the cost. Some species are capable of doing billions of dollars of damage once they get established. For example, the zebra mussel and the quagga mussel are invasive species found throughout lakes and reservoirs of the U.S. They form incredibly dense colonies and can clog pipes, damage infrastructure, and boats. Keeping pipes free from the mussels takes a lot of time, energy, and money. If water can’t get to where it needs to go, that isn’t an optional problem. It must be addressed.
Another good example is cheat grass, it’s an invasive species of grass found throughout the western U.S. It has very little nutritional value, so wildlife and livestock end up having less food, but cheat grass also loves fire. Cheat grass burns like nothing else and it re-establishes after a fire very quickly. A healthy landscape would have a diverse mix of grasses with some more adapted to summer conditions and some doing better in spring or fall. The ability of cheat grass to push out this diverse mix of grass and completely take over means the species that rely on those native grasses have now lost everything they need to survive. Instead, we now have a landscape that is a much higher fire risk and fighting fires is very expensive.
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