Environmental Engineering Reference
In-Depth Information
3
invasive species
Tracy Holcombe and Thomas J. Stohlgren
It is well known that invasive species are a problem of epidemic proportions around
the world, causing economic losses of up to $120 billion per year in the USA alone
(Pimentel
et al
. 2005). As trade and travel across international boundaries increase,
so do invasions (Mack and Lonsdale 2001). Early detection and rapid assessment are
effective strategies to minimize the impacts that invasive species have on economies
and on ecosystems that they invade (Rejmanek and Pitcairn 2002). Because the task
of invasive species control can sometimes be daunting, managers need to be able to
set priorities for prevention and control of these organisms (Byers
et al.
2002). It is
important to obtain accurate assessments of location and abundance of invasive spe-
cies so that managers can set these priorities and have the information to quickly and
effectively combat the invaders. It is also important to identify barriers to invasion
and habitats where an invasive species cannot persist or cause much harm.
To be informed in the initial stages of a species on the way to becoming a success-
ful invader, we need early detection. Early detection is a very low probability event
that is critically dependent on adequate surveillance. It involves sampling strategies
su ciently rigorous to detect incursions at su cient frequency and, assuming a
response programme, to infl uence the chance of establishment and spread.
In our quest for early detection it is important to remember that invaders can be
any type of organism—from microbes to mammals—and come in many forms.
We need to be aware of plants, animals, insects, pathogens, and parasites that
can all be invasive or be vectors for invasions. Examples of these include plague
(
Yersinia pestis
), West Nile virus (
Flavivirus
spp.), gorse (
Ulex europaeus
), com-
mon cord-grass (
Spartina anglica
), nutria (
Myocastor coypus
), and sudden oak death
(
Phytophthora ramorum
). h ere are many well-known examples of invasive plants
and animals, including feral pigs (
Sus scrofa
), miconia (
Miconia calvescens
), red
imported fi re ant (
Solenopsis invicta
), and starlings (
Sturnus vulgaris
). Fish examples
include western mosquito fi sh (
Gambusia a
nis
), carp (
Cyprinus carpio
), brown
trout (
Salmo trutta
), and Nile perch (
Lates niloticus)
. h ese notorious examples
would have benefi ted from early detection and rapid assessment.
