Invasive species; threat to natural ecosystem and biological diversity

Around July 2017, several national dailies of Nigeria reported the seizure of three containers containing 140 species of snakes with another 660 sorts of other animals, which includes millepede, hairy frogs, geckos and spider.

Some of the snake species identified are Bitis gobanica, Boiga pulverinata Atheris squamigera to mention few.

By Gustavocarra - Own work, CC BY-SA 4.0, Trichobatrachus_robustus

Why they were imported into Nigeria, nobody knows. But we have sufficient snake, geckos, millepede frog etc here in Nigeria and some of them are dangerous in their own capacity.

We actually thank the custom guys at the Port who were vigilant enough to have detected some of these animals that would have become INVASIVE SPECIES if they had escaped from the container and occupy available niches in the ecosystem existing here already!.

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Let's take a look at what invasive species really are, and what is their effect on existing ecosystem.
Invasive species are those organisms be it plant or animals that are not originally found or not native of a particular ecosystem, and are capable of harming the species that are native to the ecosystem or even human and the economy of the environment housing the ecosystem.

It's not really necessary that we could just exclusively use the term invasive species as if they all move to a new ecosystem by their own volition. The term is also used for species introduced into a new habitat, but on getting there, it began to negatively affect the ecosystem environmentally or ecologically.

They could disrupt their new habitat they invaded by taking complete dominion over the entire regions, be it wilderness or wildland-urban interphase from the natural species that originally Control the region.

Some examples of plants species that exhibit these traits are known or refers to as non-native invasive plant, and they are tagged as exotic pest plant and invasive exotic that are developing in a community known to be habitat of native plants.

The invasive species could be terrestrial species, marine, or even pathogens. This species like I earlier discussed could cause harm to native species and can even outsmart the native species when there is need for competition, they could even become predator on the native species.

At Florida in the United States, several Burmese Python with the namePython bivittatus , that invaded the natural ecosystem in the Everglades began to hunt for animals that are native to the Everglades ecosystem.

Several of them feed on deers, alligators, native birds and some other animals.
Some were as long as 18 feet. They find the ecosystem habitable to them because of Everglade favourable weather condition to them.

As it is known that competition is a general phenomenon among all species in other for them to survive, the case of invasive species seem to be a bit weird, because they possess a peculiar traits or I should say specific combination of traits which permit them in competition with native species to outwit them. Competition could be on anything, be it growth rate and reproduction, or in some cases direct interaction of species with each other.

After the 2011 Japanese tsunami, the shores of the east coast of United States was flooded with about three hundred different species of marine organisms that got themeselves attached to different debris that were washed across the ocean. That's from one continent to another, you would say.

It was reported that in science history, that would be the first time that various groups of coastal species would float across an ocean.

Invasive species adaptive character.

These Invasive species possess some attributes that make them to thrives in the ecosystem they invades.They are listed here.

• Fast growth rate ability
• Ability to reproduce rapidly
• Ability to disperse rapidly
• Phenotype flexibility (ability to change their growth mechanism to conform with the new environmental condition)
• Ability to tolerate various environmental condition
• Ability to take any type of food.

How do they alter the invaded ecosystem?

Invasive species take over their invaded ecosystem by releasing some chemical compounds, changing the Abiotic factors or modifying the behavior of plant eaters, forming a positive or negative effect on other species. Most of the invasive species produces allelopathic compounds, which affects the survival of the native organisms in their own ecosystem. Example of some invasive plant species such as Kalanchoe daigremontana release allelopathic substances that inhibit other species competing with it. Some other species may influence the seed of native plants by creating microclimate condition which is quite different from the general climate of the area and also prevent the activities of herbivores when the seeds are just growing.

How are invasive species been carried around ?

Different vectors has been identified as medium through which invasive species moves around. Let's check few known examples.

Invasive species could be carried around by many vectors; human activities, and natural phenomenon. In the Burmese python invasion at Everglades, it was uncertain whether it was human activities through pet owners releasing the creature or natural phenomenon ; the hurricane Andrew in 1992 that released that invasive creature from captivity

Natural phenomenon are known to be helpful for these non-native species invasion. Human activities in non-native invasion to another ecosystem is more prominent than the one mediated by natural extension, except in few cases human helps to carry specimen over large distance.

Human activities

Early record of human acting as vector happened when early human took rat called Pacific rat (Rattus exulans) to Polynesia a subregion of Oceania.

Humans activities that supports non-native invasion include pet trade. This involves movement of animals from one border to another,just like I explained in the opening of this post. Imagine the consequence if any of those poisonous snake or those hairy frog which are confirmed to be completely strange to ecosystem in Nigeria escaped while they are been transported?.

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Invasive species can stow away by sticking themselves on a transporting vessel on water or even transporting vehicle on land.

North American Comb jellyfish was reported to leave it's Natural habitat of Atlantic Ocean and moved with a cargo ship to established a niche for itself on the Black Sea located between the Eastern Europe and the Western Asian. Within the space of ten years, it's population had destroyed the population of anchovy which is a small forage fish, the native species of the water body.

By Dan90266 - https://www.flickr.com/photos/dan90266/37269957/, CC BY-SA 2.0,

Some of these stow away marine organisms left a devastating impact on their new marine habitat just like the jellyfish decimating the forage fish. This completely brought wreckage on the ecosystem and also the economy of the people.

In the recent times, the United States Environmental Protection Agency (USEPA) came to notify the public that a zooplankton original to Europe and Asia was found in a western basin located at Lake Erie.

It was unknown how this zooplankton known as rotifer Brachionus leydigii got to the lake, but it can not be unconnected with contaminated ballast water( Water inside ballast tank that provide stability for ship on the sea) discharged from ocean liners.

This rotifer Brachionus leydigii was identified in a survey of ballast tanks of ocean liners moving into the lake, though these species are not identified on the lake themselves, their effect on the lake couldn't be ascertained.

Several non-native species of organisms had been identified in the great lakes which now housed them in the recent. The rate at which new species are been discovered rised more than ten years ago when it was discovered that almost two new species are been discovered per year.

Concern raised over the invasion made the shipping companies to deviced method to reduce the role of ocean liners in transporting non-native species to the great lake. That lead to the requirement of the ships to flush their ballast water tank with mid-ocean salt water. However, Scientists disagree with the arrangement that it never stopped the invasion. It was claimed that the invasion of new species into the lake never stopped. Later, a new set of standard was made for ballast water discharged which requires all ocean liners sailing into the lake and other body of water in the United States to carry on board treatment systems that could destroy ballast hitchhikers.

Natural phenomenon

Just like the tsunami incidence of Japan where marine about three hundred species of marine habitat cross over ocean from one continent to another.
Also, plant species native to an ecosystem can become invasive if there seems to be long term rainfall. Disturbance to a natural ecosystem too can encourage invasive species to spring up.

Economic impact of Invasive species

Just as invasive creatures are harmful to their invaded ecosystem, the economy of human is not spared as well. The damages they brought to the ecosystem with their activities requires immediate human intervention to save the invaded community from total collapse. United States of America reports spending $137 billion annually to correct the damages and loss incurred by the activities of Invasive species.

In developing economies of the world where agricultural activities is the sole source of income, damages caused by invasive species on their agricultural system do severely leads to a poor performance of economy. The estimated annual lose globally has been put at US$1.4 trillion, this is said to be up to
5% of global GDP. Some countries such as South Africa, Brazil and India, the cost is estimated at 96%, 112% and 78% respectively

One of the means by which they battered the economy is by displacing the native plants species that economy depends on. The native plants that wildlife animals depends on are lost gradually due to the rate at which the more prolific non-native species produce several seeds and quickly spread. Reduction of biodiversity set in and monoculture of the non-native plant species is established where diverse species would have normally grow. Some even display their dominancy by completely eradicating other plants and they are the only ones we could see like stiltgrass.

The presence of Invasive species also affects income from the aquatic system. The presence of these species can result in the decline of fish production that are native to an aquatic system. The presence of Invasive species affects quality of water and the entire aquatic ecosystem. Death of aquatic life set in due to metabolic activities of some of these invasive species.

Fighting back the invasion

Since they are not really needed, why don't we get rid of them?. Getting rid of several invasive species required expertise, and it is attainable if detection is early. Most times, when their population has blown out of proportion the control might be a bit difficult. When the available resources is limited or when level of infestation hinder complete eradication, one of the means that could be employed is to reduce their density and space covered to the level they no longer poss threat to biodiversity of the ecosystem they invaded.

Some of the control means that can be employed include mechanical, manual, chemical, cultural and biological methods. The method that will be applied depends on the life cycle of the invasive species and scientific understanding of the control method that will be economical and efficient.

Combination of methods which will both prevent and control invasive species will be an effective means to protect ecosystem from collapsing due to spreading of the non-native species.
Expert advice is a great way of getting rid of the unwanted species.

Conclusion

Invasive species are not to be left unattended do. Most of the time, human action propelled the invasion of these species to an ecosystem where they wreck havock. The control of Invasive species need a serious scientific understanding so that the native species are not affected negatively while removing the Invaders.

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References

Punchng.com/customs-seize-140-imported-snakes-660-other-animals

Stowaway-species-threaten-biodiversity

Japan-tsunami-brought-300-species-across-ocean

Non-native-species-emerges-great-lakes

Wikipedia.org/wiki/Invasive_species

Invasives/control

Straying-from-trail-spreads-invasive-species