New York City, 1908: different
colorsa flag that shows its nationality
of skin swirl in the great melting pot to produce a cultural medley. Now imagine
such
a metropolis spreading to cover every
last
crevice on Earth. Over time, people will weave to produce an unprecedented uniformity; once discrete identities would be lost. Our heritages will be remembered only by the history texts in the hands of our progeny. A similar effect can be observed in environmental systems: we are in danger of losing our global
biodiversity
to a monotonous fate. The
threat
of invasive
species
is now greater than the world has ever witnessed. The number of introductions caused by international commerce is enormous (Mooney and Cleland, 2001).
Although
only a small portion of
, those survivors have aggregated to form a giant global problem of
bioinvasions
(Mack et al., 2000). Extensive studies have been done on many
exoticsbeing or from or characteristic of another place or part of the world
,
such
as the zebra mussel Dreissena polymorpha, and their biological and ecological threats prompt human interest and intervention (Facon et al., 2006). Environmentalists advocate the awareness of invasive
species
and governments spend millions to purge them.
However
,
species
removal is not as simple as it seems; we must be aware that the removal of an invasive causes
ecosystem
disturbance, just like its introduction, and hasty action can cause irreparable damage to our global asset of
biodiversity
. Extensive and specific studies of the risks and rewards of invasive
species
removal should be done before any actions to
control
a
bioinvasion
.
The greatest danger in dealing with invasive
species
involves risks in disturbing an
ecosystem
, especially
one
that's already threatened by an exotic. There are many studies
on the effects of these unwanted immigrants, but
for these ecological disturbances are still unclear (Mack et al., 2000). Even less understood are the consequences of their removal. A study on the effects of
trout
on frogs showed that native populations can dramatically rebound upon extirpation of the invasive predator (Vredenburg 2004).
However
, studies like
this
may not have strong implications on the majority of
bioinvasions
.
This
study was carried out in isolated mountain pools. With the exception of the introduced
trout
, these
ecosystems
have had minimal disturbance and human contact.
This
is quite different from many other
bioinvasions
that happen in peoples' backyards.
Insufficient understanding of invasive mechanisms can have catastrophic ramifications. In French
Polynesia
, the predatory land snail Euglandina
was deemed a fix to the
threats of the giant African land snail Achatina
. Convinced by experiences with A.
in Hawaii, a hasty French Polynesian government
this
invasive
control
project
into action (O'Foighil 2006). The resultant extinction of nearly all endemic Partulid
species
is a painful lesson today (Coote and Loeve, 2003). Hawaii and French
Polynesia
are both
pacificthe largest ocean in the world
archipelagos, but their differing
ecosystems
led to the tragedy of the Partulids.
precedence cannot always be generalized and applied to foreign problems. Specific studies of any target invasive and
ecosystem
must be done before drastic actions are carried out.
The removal process itself is extremely tedious and in some cases near impossible. The removal of
trout
from five isolated lakes in Sixty Lake Basin of California took six years (Vredenburg 2004). Similar cleansing of downstream lakes that could receive upstream fish would require even greater efforts. In the case of E.
in French
Polynesia
, removal is thought to be impossible. The carnivorous snail has infested every corner of numerous French Polynesian islands, eliminating any possibility of Partulid reintroduction (Coote and Loeve 2006).
The ability of
bioinvaders
to hybridize with native
species
to produce a spectrum of pseudo-
exoticsbeing or from or characteristic of another place or part of the world
difficulties faced.
This
is most common among plants, which can
also
undergo extremely rapid evolution (Callaway and Maron, 2006): in England native
species
of the genus Senecio
have readily hybridizedSuggestion
readily hybridize
readily hybridized
with
exoticsthe study of the physical properties of sound
to produce offspring that have taken over the country (Facon et al. 2006). In
such
cases, total extirpation of non-natives would require the elimination of more than
one
species
and looms as a truly daunting task. As can be seen, removal projects are not always pragmatic or even possible. Studies like the English Senecio
project
help elicit the mechanisms for
bioinvasion
and gauge the practicality of
control
projects so we do not waste effort on an impossible task. Similar research should be done on all
exoticsbeing or from or characteristic of another place or part of the world
before invasive removal projects.
The economic costs of invasive
species
total over
one
hundred billion dollars a year in the United States alone, and millions more are spent to
control
or eliminate them (Mack et al., 2006).
However
, the benefits of
such
projects aren't always clear even upon completion. We assume the noble goal of restoring a native
ecosystem
, yet actual outcomes can be less-than-equitable compromises. In the mid 20th century the United States government extirpated arctic foxes that had been introduced
the Aleutian archipelago fifty years earlier (Croll et al., 2005). Now half a century later, once fox-infested islands still bear the scars of the
bioinvasion
despite the success of the fox removal
project
. Seabirds are slow to recolonize the once dangerous islands, and the lack of guano leaves them under blankets of tundra. Again, research to understand the mechanisms of
bioinvasions
could have helped predict
this
outcome and prevent implementation of
such
wasted efforts.
We launch invasive removal projects to save the natives;
however
, are we actually helping them by removing an invasive? Environments that have been exposed to an exotic for sufficiently long periods have reestablished equilibrium:
species
have developed adaptations to cope with their new
neighborsa person who lives (or is located) near another
. Off the coast of New England, mussels exposed to predatory crabs develop thicker shells as protection (Freeman and Byers, 2006). In Australia, snakes evolved smaller relative head sizes to cope with the introduced toxic cane toads (Phillips and Shine, 2004). These morphological changes represent investments to increase fitness in altered habitats. The energy cost of these features is balanced by an increased ability to survive. By removing invaders, we are eliminating the benefits of their adaptations. These disturbances would leave the native
species
with just the adverse costs of thickened shells and smaller heads. In dealing with
bioinvasions
, we must consider not only the native
species
, but
also
the dynamic
ecosystems
. Disturbances can draw out unforeseen effects; like the fox removal
project
in Alaska, a disturbance with the noblest of purposes can fall short of recovery.
Invasive
species
are a
threat
to the world's
biodiversity
, but their removal can be just as hazardous. Even with the right goal, without proper planning and sufficient studies to understand target
ecosystems
, projects in invasive removal can prove futile or even produce dire consequences. Fortunately for Partulids in French
Polynesia
, at least
one
extant member of each endangered
cladeany collection of particles (e.g., smoke or dust) or gases that is visible
has been discovered and some hope of recovery still exists (O'Foighil 2006). Yet many organisms have no immediate relatives: the dead
cladeswearing or provided with clothing; sometimes used in combination
walking are survivors of past mass-extinction events and their loss would be irreparable (Jablonski 2001).
When controlling the global problem of invasive
species
, prevention outshines restoration. Most modern
invasives
are spread by artificially, either as unwitting stowaways or intentional imports.
the average citizen, the awareness of
biodiversity
is often masked by personal, political, and economic concern. The
threat
of
bioinvasions
must be publicized and personalized. Only
the aggregation of countless personal efforts can a global
threat
be contained. In New Zealand, invasive
trout
are a publicly supported economic boon (Townsend 2003). Any extensive lobbying for the continued existence of a
species
is admirable. If people were just as aware of the value in their endemic
biodiversity
, curbing the spread of exotic
species
would take an easier turn