- Mutation as a source of variation
- Introduced species and biodiversity
- Invasive species
- Human activities that threaten biodiversity
- How does climate change affect biodiversity?
- How did all dinosaurs except birds go extinct?
- Were dinosaurs undergoing long-term decline before mass extinction?
- Human impact on ecosystems review
- Disruptions to ecosystems
What causes a species to be considered invasive. How invasive species can damage ecological communities.
- Invasive species are species that have been introduced into areas outside their native range and can cause—or have caused—harm in their new area.
- Invasive species may outcompete native species for resources or habitat, altering community structure and potentially leading to extinctions.
- Asian carp illustrate the potential impact of invasive species. Introduced into the United States by humans, these fish species have colonized waterways and may threaten native fish populations, and fisheries, in the Great Lakes.
Take a look at the photo below. Just another pretty morning drive in the hills of Tennessee! But wait a minute ... those trees ... they're covered with something. Look closer, and you'll see that almost the entire landscape is covered with a thick, green blanket. This blanket is made up of an invasive plant called kudzu.
Kudzu is one dramatic example of what can happen when a species gets introduced into a new ecosystem where it has abundant resources and few predators. The kudzu plant was introduced to the United States from Asia in the late 1800s as an ornamental plant, and it and was planted widely in the South in the early 1900s to reduce soil erosion. What the people who planted this vine did not know was that it would rapidly take over the landscape, growing as much as a foot a day and enshrouding ground, shrubs, trees, and even houses and old cars in a suffocating girdle of vines.
Invasive species like kudzu are a vivid—and scary!—example of how ecological changes, including those caused by humans, can alter communities and ecosystems. In this article, we'll look in more detail at what an invasive species is and how invasive species can disrupt ecosystems—often reducing the numbers of native species and altering the overall structure of the community.
What is an invasive species?
An invasive species is a species that has been introduced to an area outside of its native range and has the potential to cause harm—or has already caused harm—in its new location.
Many invasive species are found in the United States, and a few examples are shown in the pictures below. Whether you're enjoying a forest hike, taking a summer boat trip, or just walking down a city street, chances are that you've encountered an invasive species.
Case study: Asian carp
Let's take a look at what's arguably the kudzu of the aquatic world: the Asian carp. Since they were introduced to the United States in the 1970s, Asian carp have rocketed in numbers thanks to their vast appetite and speedy reproduction, now forming up to 95% of the biomass in some Mississippi and Illinois rivers. Not only that, these fish have led to an international lawsuit about waterway access between the United States and Canada! This is a dramatic example of what can happen when an invasive species gets a foothold in a new place.
Where did this story begin? Asian carp—which are not a single species, but a group of related species—were introduced to the United States in the 1970s.
They were imported largely by fisheries and sewage treatment plants, which used the carp's filter feeding abilities to rid ponds of excess plankton. However, some fish escaped. By the 1980s, these fish had colonized waterways of the Mississippi River basin, including the Illinois and Missouri Rivers.
Because they are big eaters and fast reproducers, Asian carp can often outcompete native fish species with whom they share habitats and food sources. Black carp eat mussels and snails, limiting their availability for native fish and damaging shellfish populations. Another Asian carp species, the silver carp, eats plankton, a key food for many native fish species in their larval and juvenile stages.
Although Asian carp can be eaten, the fish are bony and are generally not a desired food in most parts of the United States. Also, if you go out for a fishing trip, be careful: you could get smacked by an Asian carp! The fish, frightened by the sound of approaching motorboats, often thrust themselves into the air and may land in the boat or directly hit the boaters, see jumping carp below.
The Great Lakes and their prized salmon and lake trout fisheries are also threatened by the Asian carp. These invasive fish have already colonized rivers and canals that lead into Lake Michigan, including the major supply waterway linking the Great Lakes to the Mississippi River.
To keep the carp from leaving this canal, electric barriers have been used to discourage migration. However, the threat is serious enough that several states and Canada have sued to have the Chicago channel permanently cut off from Lake Michigan. We don't yet know whether the Asian carp will prove to be mostly a nuisance—like invasive species such as the zebra mussel—or whether it will ultimately destroy the largest freshwater fishery in the world.
The story of the Asian carp shows how population and community ecology, fisheries management, and politics can intersect and how ecology can have very real importance for the human food supply and the US economy. On a more personal note, it also shows how ecology can matter for folks enjoying a day on the river ... who might happen to get smacked with a flying carp!
Want to join the conversation?
- What damage can European starling do(6 votes)
- The article states, "The European starling, Sturnus vulgaris, may compete with native bird species for nest holes." This means they can take nesting holes away from the native birds, profoundly reducing the native bird's population.(12 votes)
- Can releasing a pet into the wild like a turtle or an ant potentially turn it into an invasive species? Has this happened?(2 votes)
- Releasing a single pet into the wild is not likely to cause a problem but that is rarely the case where a single animal is released.
For example the seemingly innocent goldfish is a species of carp that is not native to the US and is a fish that can grow to be 16 to 19 inches and weigh more than two pounds and has few natural predators and reproduces fairly quickly. They out compete other species and even eat their eggs.
Pet Burmese pythons being released have cause a drastic reduction in population of raccoons, foxes and bobcats in the ecosystems they have now become common in.(4 votes)
- Why does the asian carp thrust in the air instead of swimming away?(3 votes)
- Why do we not, as humans, consume large amounts of Asian carp instead of other fish species endangered by the carp? Is there an issue with the taste, or do they contain large amounts of mercury? I am genuinely curious. I understand they are bony, but can't we just suck it up?(2 votes)
- The biggest issue is American perception. Most people in the US simply don't like the thought of eating carp. People tend to associate all carp--invasive or not--with "bottom feeder", which leads to the perception that they taste muddy or are just dirty all around. Even if not all carp are bottom feeders (the Asian carp is not a bottom feeder), their reputation as one means that people in the US are going to shy away from the idea of eating them. It's the same reason why most people in the US shy away from the thought of eating rats, even though they are enjoyed in places like Spain and Polynesia.
Thus, in order to get more people in the US to eat carp, people have to change their perception or market the carp differently. Asian carp has been sold under the name "silverfin" before, and many people enjoy it! It is a promising way to get some delicious food while helping the environment. Once that big hurdle of public perception is passed, more people will being to eat the carp and save the environment.
Does this help?(2 votes)
- The article states, "The European starling, Sturnus vulgaris, may compete with native bird species for nest holes." This means they can take nesting holes away from the native birds, profoundly reducing the native bird's population.(2 votes)
- so is there carp in the Mississippi river yet?(1 vote)
- how did they get here
asian carp(1 vote)
- In the 1970s, Asian carp were introduced to aquaculture ponds and wastewater treatment facilities to help keep them clear of weeds and parasites. Flooding of the areas caused them to escape from these facilities into other areas.(1 vote)
- how did they know how population and community ecology(1 vote)