Environmental Engineering Reference
In-Depth Information
solutions will be needed (see Box 14.1). For example, the seastar
A
.
amurensis
is a
notorious predatory pest. Life history characteristics that make it a successful
invader—asexual and sexual reproduction, high fecundity, extended planktonic
larval stage, wide environmental tolerances, and its ability exploit a wide range of
prey types and habitats (NIMPIS 2002b; Ross
et al
. 2003)—refl ect the inadequacy
of current management tools. Given the very high densities of
A
.
amurensis
larvae
observed in some port environments (among the highest ever reported for seastar
larvae in the port of Hobart, Australia; Bruce
et al
. 1995) and the association of
this species with shipping vectors such as ballast water (Ross
et al
. 2003), the pest is
highly likely to spread to new regions. Eff ective post-border management tools for
these types of species do not exist, and solutions will need to be found in the devel-
opment of new methods such as molecular probes for detection of propagules (e.g.
Deagle
et al
. 2003), or the development of semiochemical and other technolo-
gies for pest attraction (e.g. Ingvarsdóttir
et al
. 2002). For any new management
methods, however, there is clearly a need to balance management e cacy against
the risk of collateral impacts on the wider environment including social factors. In
many instances, this may mean that promising but potentially high risk solutions
will be publicly and politically unacceptable (h resher and Kuris 2004).
Box 14.1
Novel solutions for early detection of marine invasive species,
and rapid response
Ballast water
Ballast water is a major mechanism for the transfer of AIS from source regions
to new locations worldwide. Planktonic stages of many marine organisms are
entrained in ships' ballast water, transported to new bioregions, and expelled
when ballast is discharged. In order to effectively manage the invasion risk posed
by ballast water, we need to know which unwanted species are being transported,
by which ships, and at what densities. Species-specifi c identifi cation of plank-
tonic organisms in ballast water can be problematic, however, particularly for
larval and juveniles stages.
Recent advances in genetic and molecular methodologies may be the answer
to effective ballast water management. A polymerase chain reaction (PCR)-based
test for detecting DNA of the northern Pacifi c starfi sh
Asterias amurensis
has suc-
cessfully been developed (Deagle
et al
. 2003). This powerful technique overcomes
many of the limitations of ballast water sampling, by successfully detecting single
larvae in large amounts of mixed plankton. It is also very species-specifi c—able to
distinguish larvae of
A
.
amurensis
from other
Asterias
species. Along similar lines,
a fl uorescent
in situ
hybridization assay has also been developed for the detection
of
A
.
amurensis
in ballast water (Mountfort
et al
. 2007). This fl uorescein-labelled
species-specifi c probe targets
A
.
amurensis
larvae, allowing for their easy detection
in ballast water samples without the necessity of expensive equipment. With further
