Environmental Engineering Reference
In-Depth Information
Application issues
Benefi ts
Limitations
Specialized equipment
required
Not effective on
non-uniform surfaces
Labour intensive
Only practical over
small areas
Environmentally friendly
Unselective
Diffi culties in achieving
suffi ciently high water
temperatures
Only suitable for early life
stages
Diver safety issues
Applied above-water
Specialized gear may
be required to remove
vessels (i.e. dry dock)
May inconvenience port
operations
Cost-effective
Environmentally friendly
Removal of some struc-
tures (i.e. vessels) may be
expensive
Some organisms can survive
for extended periods out of
water
Logistical issues
involved if large
amounts of freshwater
are required
Cost-effective
Environmentally
friendly
Some species (i.e. mussels)
can survive for extended
periods in freshwater
can comprise only one component of a successful eradication eff ort. In Japan,
scallop dredges are used to periodically remove
A
.
amurensis
from areas of the sea
fl oor in scallop harvesting plots (Ito 1991). While seastars reinvade the cleared
areas, a signifi cant number of scallops can be harvested before reinvasion becomes
a problem (McLoughlin and Bax 1993). Aside from the obvious physical damage
caused by dredging, environmental impacts of this type of control would be high
in areas where resuspended sediments are highly polluted (McEnnulty
et al
. 2001).
Dredging and trawling have also been demonstrated to change the characteristics
of some soft sediment habitats in a way that inhibits the further settlement and
attachment of many non-target sessile invertebrates (Stead 1971a,b).
14.3.2.2 Wrapping and smothering
A variety of materials including plastic sheeting, rubber, jute matting, and dredge
spoil have been used on a range of artifi cial and natural surfaces to control a range of
