Environmental Engineering Reference
In-Depth Information
In contrast, none of the perch sampled in Salford Quays had intersex gonads. The
apparent difference in sensitivity between perch and roach in Salford Quays was
ascribed to different routes of exposure through feeding. Perch feed on zooplank-
ton and other fish whilst roach tend to consume a relatively large amount of
detritus whilst foraging in the silt thus increasing their exposure to potentially
contaminated sediments (Conlan et al.
2006
). The overall impacts of feminisation
on fish populations are, as yet, poorly understood (Conlan et al.
2006
).
Future challenges
Considering that the waterside development and ecological recovery at Salford
Quays, in common with similar developments both nationally and internation-
ally (Hoyle et al.
1988
), is due to the water quality improvements, the import-
ance of routine monitoring and management of the water itself cannot be
understated. The success of Salford Quays since 1986 has been possible only
through development and implementation of a holistic and dynamic monitor-
ing and management plan. For example, the recent natural colonisation of
macrophytes in the Quays was a prospect previously not envisaged. Neverthe-
less, the management strategy has been modified to account for this and other
developments of the ecosystem such as the initiation of sampling the leeshore
in response to the presence of Microcystis sp. from the early 2000s.
Implementation of oxygenation remediation within the Turning Basin in
2001 has resulted in a dramatic improvement in water quality, aesthetic value
and ecology of the upper reaches of the MSC. The number of pollution sensitive
macroinvertebrate species has increased and BMWP scores suggest that the rate
of increase in the Turning Basin has been accelerated as a result of the elevated
oxygen concentrations. Gudgeon which were absent from the MSC for many
decades are now ubiquitous and in fact dominate recent catches in the oxygen-
ated region. Condition of roach, as determined by Fulton's Condition Factor, is
also excellent, being similar to recent figures for fish in Salford Quays. Despite
improvements in water quality over the last few years however the MSC
remains a borderline habitat for fish populations. Episodic pollution and major
habitat limitations such as spawning habitat, nursery areas and food resources
for juveniles in particular still restrict the potential for self-sustaining popula-
tions in the longer term.
A further factor affecting the future success of the MSC regeneration is the
requirement for frequent dredging. Dredging is essential for navigation and
flood control, though the stresses exerted on water column oxygen concen-
trations can be severe, particularly during the summer months. This leads to
the possibility of widespread mortalities of macroinvertebrates and fish. More-
over, low oxygen concentrations could lead to the release of sediment bound
phosphorous which, if matched with a reduced sediment load and thus turbid-
ity, could in turn promote algal blooms. In addition, toxic heavy metals and
