Environmental Engineering Reference
In-Depth Information
A recent synthesis of biological invasions in New Zealand by Allen and Lee
(2006) provides a number of examples where the e
cacy of post-border manage-
ment of pests in terrestrial and freshwater systems has been demonstrated. h ese
include: successes in the restoration and recovery of native vegetation through
control of introduced herbivores such as rabbits, goats, and deer (Coomes
et al
.
2006); control programmes for introduced predators (e.g. stoats, rats) of native
birds or their eggs (McLennan 2006); spraying programmes for invasive aquatic
and terrestrial weeds (e.g. Swales
et al
. 2005); the release of biological control
agents (e.g. for insects) and commercial harvest for introduced mammals (e.g.
goats, deer, and pigs, Parkes 2006a). h ese examples and many others highlight
a wide range of control strategies. In contrast to freshwater and terrestrial sys-
tems, the marine environment is highly inter-connected and expansive, relatively
inaccessible, and is often hostile to work in. Intuitively, it is apparent that many
of the methods developed for freshwater and terrestrial systems are unlikely to be
directly transferable to the marine environment. And in fact, there is a longstand-
ing view that management of marine pest incursions post-border will generally be
futile (e.g. Sanderson 1990; Brown and Lamare 1994; h resher and Kuris 2004).
h ere is, however, emerging evidence that management may be feasible under
certain circumstances.
Surveillance and monitoring programmes for the early detection of new incursions
form the fi rst stage of an effective post-border management strategy. Once a threat
has been detected, the next stage involves determining the most effective response
actions, which include complete eradication, containment measures to slow or
prevent the spread of the organism, or population control to reduce pest densities
to levels that minimize adverse effects (Fig. 14.1). The level of response will depend
on a combination of factors, including:
•
Potential impacts of the organism on the environment, economy, and
people.
The feasibility and risks of response options.
•
•
The ability to target the invasive species.
•
Public concern or interest (Wotton and Hewitt 2004).
Baseline biological surveillance and monitoring is crucial for eff ective rapid
response to new incursion events in the marine environment. Surveillance pro-
grammes aim to collect baseline information on the identity and numbers of spe-
cies within areas deemed to be of high risk of incursion (e.g. ports and marinas)
in order to identify new arrivals (Hewitt and Martin 2001). Large-scale baseline
monitoring programmes of this nature, such as the multinational GloBallast pro-
gramme, are being increasingly promoted in a range of countries such as South
Africa, India, Brazil, China, Ukraine, and Iran (Global Ballast Water Management
Programme 2004). In Australia, baseline biological surveys have been completed
