Environmental Engineering Reference
In-Depth Information
Organisms can be introduced into an area many times, but never become estab-
lished or invasive, yet for others a single event is all that is needed. The establish-
ment of an invasive species is therefore the end point of a combination of many
coinciding events and conditions.
Islands that are isolated by signifi cant stretches of water (sea) and areas isolated
by signifi cant biological or geographic barriers, such as deserts, have distinct
advantages in their ability to control the entry of terrestrial invasive organisms.
Under such circumstances the prevention of entry of invasive species can be a
realistic option. However, where there is limited or no biological or geographic
isolation then to have a system totally focused on the prevention of the entry of
invasive species is fraught with practical di
culties. Under such circumstances,
prevention in combination with other strategies, such as very good early detection
and management systems, are more likely to lead to a more robust system that
lowers the number of invasive species establishing and becoming problematical.
h is combination of strategies implemented in both non-biologically isolated and
biologically isolated areas will provide the greatest opportunity to minimize the
impacts of species that do enter. Measures that involve early detection, with contin-
gency plans for eradication/containment of invasive species that can be e
ciently
implemented, are more likely to have a higher cost/benefi t outcome.
h e same situation exists for aquatic or marine invasive species—where there are
signifi cant biological barriers or isolation, there is the potential to develop work-
able quarantine measures. However, complicating factors in aquatic systems are
that there is little biological separation when water is the vector and by practices
such as the discharge of ballast water by vessels and the fouling of hulls of vessels.
A history of invasiveness and patterns for specifi c species in the Pacifi c region can
be found on the PIERS database for the Pacifi c region (
http://www.hear.org/pier/
Invasive species occur in most taxa, a few examples of species in various taxa and
broad categories of introduction are given in this chapter. Table 1.1 summarizes
general problematic organisms associated with broad categories.
Table 1.1
Summary of potential quarantine issues associated with organisms.
Organism type
State
Potential quarantine/
invasive issues
Terrestrial plants
Live
•
Invertebrate pests
•
Diseases
•
Weed potential
•
(Soil associated with plants
carry further risks)
Dried foliar (non-viable)
•
Disease
Dried stem (or thicker
plant parts)—non-viable
•
Diseases
•
Invertebrate pests
