How does introduced species affect the environment

They can spread on even the smallest scales — so learning more about them is the key to a better future. Not all non-native species are invasive. In fact, some are standard and a normal part of life. Still, farmers grow it as a crop year-round. Often, people will bring invasive species in for pest control, crop growth or to sell. When this happens, the plant or animal can adapt quickly and spread. People originally brought the cane toad to Australia to control insects.

However, it is instead harming the surrounding ecosystem. Its poisonous skin can kill a crocodile. A similar thing happened with the Kudzu plant, originally native to Japan and southeast China.

In the southern parts of the U. They can be immune to venom and toxins and will withstand removal efforts. Thus, they take root or reproduce and spread until they become a norm. Invasive species impact agriculture, forestry and fishing.

Plants and animals can take over these areas and cause irreparable harm to local or global economies and the surrounding ecosystems, and can even harm humans. These species can kill off native crops and animals.

Farmers may have to downsize their land, and fishing markets may catch less viable fish to sell. Supply chains then see less business, throwing supply and demand out of sorts. Communities often depend on the natural resources around them. Some cultures need naturally growing plants and animals for food and medicine. Invasive species can also significantly harm human health. For instance, zebra mussels are not naturally found in the Great Lakes but instead are native to Russia and Ukraine.

In addition, higher average temperatures and changes in rain and snow patterns caused by climate change will enable some invasive plant species—such as garlic mustard, kudzu, and purple loosestrife—to move into new areas.

Insect pest infestations will be more severe as pests such as mountain pine beetle are able to take advantage of drought-weakened plants. Invasive species cause harm to wildlife in many ways. When a new and aggressive species is introduced into an ecosystem, it may not have any natural predators or controls. It can breed and spread quickly, taking over an area. Native wildlife may not have evolved defenses against the invader, or they may not be able to compete with a species that has no predators.

The direct threats of invasive species include preying on native species, outcompeting native species for food or other resources, causing or carrying disease, and preventing native species from reproducing or killing a native species' young. There are indirect threats of invasive species as well. Invasive species can change the food web in an ecosystem by destroying or replacing native food sources.

The invasive species may provide little to no food value for wildlife. Invasive species can also alter the abundance or diversity of species that are important habitat for native wildlife. Aggressive plant species like kudzu can quickly replace a diverse ecosystem with a monoculture of just kudzu. Additionally, some invasive species are capable of changing the conditions in an ecosystem, such as changing soil chemistry or the intensity of wildfires.

Invasive carp are fast-growing, aggressive, and adaptable fish that are outcompeting native fish species for food and habitat in much of the mid-section of the United States. The huge, hard-headed silver carp also pose a threat to boaters, as the fish can leap out of the water when startled by boat engines, often colliding with people and causing injuries. Voracious filter feeders, invasive carp consume up to 20 percent of their body weight each day in plankton and can grow to more than pounds.

Invasive carp were imported to the United States in the s to filter pond water in fish farms in Arkansas and quickly spread across the country.

Flooding allowed them to escape and establish reproducing populations in the wild by the early s. Invasive carp are swiftly spreading northward up the Illinois River, and are now on the verge of invading the Great Lakes. Once established in an ecosystem they are virtually impossible to eradicate. Adult invasive carp have no natural predators in North America and females lay approximately half a million eggs each time they spawn. Parts of the Great Lakes, including nutrient-rich bays, tributaries, and other near-shore areas, would offer invasive carp an abundant supply of their preferred food, plankton.

Plankton is also favored by most young and many adult native fishes and the voracious carp would likely strip the food web of this fundamental resource. The U. Geological Survey has identified 22 rivers in the U. The brown marmorated stink bug, Halyomorpha halys, is native to China, Japan, and surrounding countries. They were first discovered in the United States in Pennsylvania during the late s, but no one knows for certain how they were introduced to North America.

Brown marmorated stink bug BMSB populations are exploding in the absence of their natural predators, and they are quickly becoming a nuisance to people in their homes and to the agriculture industry. The bugs begin to come indoors, searching for warm, protected areas when outside temperatures turn cooler in the fall. BMSBs feed on host plants by piercing the skin and consuming the juices within; the signs of stink bug feeding appear as "necrotic" or dead spots on the surface. A wide variety of plants are known food sources for BMSBs, including ornamental trees and shrubs; fruit crops like peaches, apples, grapes, and pears; vegetable crops like green beans and asparagus; and soybeans and corn.

Zebra mussels and quagga mussels are virtually identical, both physically and behaviorally. Originally from Eastern Europe, these tiny trespassers were picked up in the ballast water of ocean-going ships and brought to the Great Lakes in the s. They spread dramatically, outcompeting native species for food and habitat, and by , zebra mussels and quagga mussels had infested all of the Great Lakes.

Invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats. This can result in huge economic impacts and fundamental disruptions of coastal and Great Lakes ecosystems.

They can be introduced to an area by ship ballast water, accidental release, and most often, by people. Invasive species can lead to the extinction of native plants and animals, destroy biodiversity, and permanently alter habitats.