Invasive Species

Introduction

What are Invasive Species?

Invasive species are species that are not native or indigenous to an ecosystem. They harm the ecosystem economically and environmentally. Many invasive species are introduced to an ecosystem while many others find their way to a new location accidentally. The invasive species often do not have predators that would kill them in the non−native area and they grow to so large in numbers that they threaten other species in the region.

All non−native species of living beings are not invasive though. There are many plants and crops in the world that are cultivated in non−native areas but they do not pose a threat to other species in the non−native area. For example, many varieties of wheat, tomatoes, and rice grown in the United States are not native to their locations but they are not invasive as well.

Invasive species adapt quickly to new locations and reproduce very fast. They threaten other species in the non−native location for these qualities. Usually, the invasive species do not have any predators who would kill them in the new location. So, their population grows very fast as they get enough food to stay alive and increase their population. Therefore, to be a species and invasive species, it must harm the economy, property, or the animals and plants in the new region.

In many cases, invasive species are introduced into a new area accidentally. For example, Zebra mussels are native to the Central Asian Seas, the Caspian Sea, and the Black Sea. They were brought to the North American Great Lakes by accident as they stuck to the large ships that traveled between the two regions. Now, there are so many zebra mussels in the Great lakes that they have threatened native species.

Introduced Species

Sometimes, some new species of animals and plants are brought to a non−native place on purpose. They are introduced to the new location often as a measure of pest control or as decorative displays. Although pest control is an important motive, people and businesses introducing species are often unaware of the consequences. Even scientists do not know exactly what could be the result of introducing a new species in a non-native location.

• Introduced species grow too quickly in terms of population and become invasive. There are plenty of examples of introduced species going invasive.

  For example, in 1949 five cats were brought to South Africa’s Marion region. The aim was to control the mice that were available in large numbers on the island. By 1977, there were 3,400 cats on the island which became a big threat to the birds of the island.

• Some other invasive species we now have are descendants of pets that were released into the wild.

  For example, many people have released pet Burmese Pythons into the Everglades. The Everglades is a swampy area in South Florida. The snakes are often huge in length, growing up to 6 meters or 20 feet in length are native to Southeast Asia. They have hardly any predators in Everglades. So, they grew unhindered in numbers and now have become a threat to birds’ limpkin and ibis, both of which are wading in numbers.

Invasive Species and the Local Environment

Most invasive species thrive because they outcompete the local species for food.

Image 1: Silver carp (Hypophthalmichthys molitrix)

For example, silver carp is a fish species that escaped from British firms in the 1990s and found its way into the Missouri river of North America. The silver carp feed on plankton. Many local fishes, such as paddlefish also feed on plankton, however, the feeding cycle of paddlefish is slower than silver carp. This has led to silver carp becoming so large in numbers in the Missouri river that paddlefish are dying out in large numbers for getting outcompeted for food.

Invasive species sometimes grow in numbers because there are no hunter or predator species that would kill them in the new location.

Image 2: Brown tree snake (Boiga irregularis)

For example, the Brown Tree Snakes that were accidentally brought to Guam in the late 1940s or early 1950s have no predators in Guam. However, there are many rodents and birds the snakes can eat in the new location. So, the snakes grew so large in numbers that they became responsible for the extinction of nine of the island’s 11 forest-dwelling bird species.

Some invasive species destroy the habitats in their new locations.

For example, Nutria are rodents found in South America naturally. They were brought to North America by Ranchers for their fur.

However, some of these rodents were released into the wild when Ranchers failed to contain them. Now, rodents have become a major pest in Gulf Coast and Chesapeake Bay area. Nutria rat rushes and tall grasses provide shelter to a large number of organisms in the two regions. They also provide security to sediment and the soil. Due to an unhindered growth in the numbers of Nutria, many species that eat the grasses or take shelter in them are now threatened for their existence.

Some invasive species harm the economy too.

Image 3: Water Hyacinth (Eichhornia crassipes)

For example, Water Hyacinth is a plant native to South America. It is now found in large numbers in many parts of the world. The plant has beautiful flowers and that is why they are introduced to water bodies in many parts of the world. But the species grows very fast, often choking out the environment or native wildlife in which they reside.

In Lake Victoria or Uganda, Water Halcynith grew so thick that boats could not go through them. The species restricted sunlight from reaching the bottom of the water bodies, preventing fishes from feeding and reproducing. As a result, Lake Victoria’s fishing industry had to suffer a blow.

Invasive species can also harm property.

Image 4: Zebra Mussels at Rossigh Bay

For example, small zebra mussels can clog the cooling systems of boat engines due to which the engines must be cleaned of the mussels in places they exist in large numbers. This requires an associated cost. Meanwhile, large zebra mussels can damage water pipes at power plants. Large zebra mussels have harmed water pipes at power plants in Lake Victoria and continued costs are being spent to keep the pipes out of reach of these mussels.

Conclusion

It is important to learn about invasive species in order to save local species from going extinct. As invasive species attack the local species they must be segregated before introduction to the wild. Hence, everyone must be aware of them.

FAQs

Qns 1. What are invasive species?

Ans. Invasive species are species that are not native or indigenous to an ecosystem. They harm the ecosystem economically and environmentally. Many invasive species are introduced to an ecosystem while many others find their way to a new location accidentally.

Qns 2. Why do invasive species grow so large in numbers in a new location?

Ans. The invasive species often do not have predators that would kill them in the non-native area and they adapt to the new locations’ conditions very fast and reproduce very quickly so they threaten other species in the region.

Qns 3. When are invasive species brought to a new location?

Ans. Sometimes, some new species of animals and plants are brought to a non-native place on purpose. They are introduced to the new location often as a measure of pest control or as decorative displays.

Qns 4. Which invasive species harmed the fishing industry of Lake Victoria in Uganda?

Ans. Water Halcynith harmed the fishing industry in Lake Victoria as they lead to a decrease in the number of fish in the lake.