The Effects of Foreign Species Introduction on an Ecosystem
The effects of foreign species introduction into an ecosystem are very profound. From
small microorganisms to species of large mammals, many foreign species introductions
occur every day. New implications of their introduction are found just as often.
When a foreign species is introduced into an ecosystem, often the ecosystem contains no
natural predators for the new species. This lack of predators sometimes leads to; in
conjunction with a supply of food suitable for the new species, a period of exponential
growth of the species. This growth and severe increase in the size of the population can
cause a shortage of food for native species. When this occurs, the native species
disappear and the biodiversity in the ecosystem is reduced. The carrying capacity is
also reduced because the ecosystem will not be capable of supporting the same amount of
life. If one species hogs the food and does not contribute itself to the food chain, the
balance is disrupted and there will be less available for the native species. Once the
new species has found its ecological niche however, balance begins to restore itself.
When the biodiversity in the ecosystem is reduced, the ability of the ecosystem to grow,
or the biotic potential, is as well reduced. More species residing in an ecosystem which
depend on each other allows for a greater chance of survival and perpetuation. This may
occur for several reasons, for example a bee and a flower. The bee requires the pollen
of the flower to make its honey. However, while gathering the pollen from the flowers,
it transfers some of the pollen to female flowers, allowing them to make seeds and spawn
further generations. However, a foreign species may, for example, eat the bees therefore
allowing for decreased fecundity of the flowers.
Another implication of the introduction of foreign species into an ecosystem is the
potential for toxins to be spread up the species chain is increased. For example, in
ports all over the world, ships empty their ballast tanks containing large amounts of sea
water, often laced with organisms not naturally found in their new region. The zebra
mussel provides food for a certain type of fish, and also contains several toxins because
it is a filter feeder. The level of toxins in the fish due to the biological
amplification is high. But if and when a new type of fish are introduced, which eats
zebra mussels and provides a more preferred food for the fish which formerly ate the
mussels, a new level of biological amplification is inserted. This results in the higher
levels containing more toxins than they previously did, which can lead to higher death
rates, and lower birth rates, which is an example of a lower biotic potential.
Finally, abiotic factors may not be prepared for the new species introduction. If, for
example, a forest has a certain amount of rocks suitable for the construction of shelter
by certain animals, and a new species moves in which also utilizes the same material for
its shelter. The rocks will be in short supply. They are an abiotic factor, without
which, animals have no shelter. The animal which takes up the building supplies but does
not provide back to the ecosystem will thrive, however the rest of the ecosystem which
depends on the native animal which is harmed, will not thrive and have a decreased biotic
potential.
In conclusion, if a foreign species is introduced, the ecosystem is often not prepared
to deal with the new competition. Because the predator-prey relationship is important in
controlling the population, and the new species may not have any predators, the
population may explode. The materials available may be compromised for the more
beneficial organisms, and overall the biotic potential and carrying capacity will
decrease. At least, until the new organism finds its niche and can contribute to the
ecological community.
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