Why are non-native species of particular concern?
They are not native, therefore they don’t belong.
If they do not
significantly affect native ecosystems, however, people are not as
concerned. It is the invasive non-native species that people are
most concerned about.
When non-native species are introduced to a new system, they often
have an advantage over native species. The new system may not
have the predators or diseases that the species had in their native
range. This may enable them to be much more successful. They
may be able to rapidly take over areas and displace native species.
Non-native species can also bring along with them non-native
diseases that native species have not evolved defenses against.
Is it always easy for non-native species to take hold?
No. Successful invasions are often preceded by several unsuccessful ones.
Introductions often involve only a few individuals. They must survive the journey and be able to withstand the new climate and physical conditions. Their numbers may not be large enough to reproduce successfully and severe climate events, such as drought, may be challenging. Non-native species often compete with native species. Remove competitors or change resource levels and invaders have the edge they need. A non-native species may have certain traits, such as abundant reproduction, that can give it a jump-start on successful colonizing.
How do non-native species get here?
International trade is a major factor contributing to the worldwide
movement of invasive species, and New York is a major point
of entry for cargo and people alike.
People also unknowingly
transport organisms. Without proper care and attention, we often
unknowingly contribute to the local and global spread of invaders.
Is an invasion of new species always harmful?
An invasion can be beneficial or harmful.
As humans, we assign a value—aesthetic, economic,
societal—on each invasion.
As a society, we appreciate
benefits derived from honey bees, from brown trout,
and from cultivating non-native grains. Many people view these
invasions as good. We do not appreciate the arrival of fire ants, wooly
adelgids, or water chestnut, and we view these events as bad. The
effects of an invasion, either by the bee or adelgid, are manifold:
positive for some of the species that they encounter, negative for
others, and some species may not be affected at all. Value depends
on your point of view. Not everyone shares the same viewpoint.
And your point of view can change.
Other than environment and other organisms, what else can invasive species impact?
Economics and Human Health
Government agencies and people in general often need
to decide how to manage or combat problems associated
with invasive species. When making decisions on what
to do about invasive species, they take other factors
into consideration. Is there a risk to human health? Is
there significant damage to an important industry? What
are the costs or negative effects of treating a particular
species? Whether a species is or is not invasive is strictly
a biological trait of that species. Economic and human
health considerations, however, come into play when
imparting human values into making decisions as to
what to do about them.
