Essay/Term paper: The effects of foreign species introduction on an ecosystem

Essay, term paper, research paper:  Science

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.