Environmental Assessment
Volume C-4.3
Slurry Pipeline
Fish and Aquatic Resources
Ambatovy Project
139
January 2006
Disturbance to resident fish populations in the water crossing locations will occur
as a result of habitat alterations (physical disturbance of instream habitats) or the
effect of increased sediment levels and downsteam deposition affecting the use
and productivity of habitats during construction. Hydrostatic testing can also
impact fish (water withdrawal from important habitats, entrainment, and
discharge affecting habitat condition in the receiving area). Through the
implementation of the construction and operationing management plans these
effects will be mitigated, largely temporary, and low impact. Long-term impacts
on fish communities may occur where permanent structures such as bridges or
culverts are installed, but they are expected to be low in magnitude. The low risk
of a potential pipeline break (Volume C, Section 3.5) during operations could,
impact water quality and biota; however, through pipeline monitoring and
maintenance the extent of impact is expected to be low.
Impacts on non-indigenous (exotic) fish communities are expected to be
negligible because of the widespread distribution, habitat adaptability and
tolerance to reduced water quality by these species in this group.
Fish Health
Changes to fish health will occur primarily on a local level as a result of the
effect of increased sediment entrainment during construction, and potential
accidents and spills into water bodies and effluent discharges into water bodies.
The effects of water quality changes (TSS) may be severe because of the soil
types, topography and extent of ground / in-water disturbances with potential for
high levels of erosion and sedimentation. The effects on fish from exposure to
sediment range from avoidance and minor physiological stress to mortality, with
the magnitude of the effect being a function of TSS concentration and duration of
exposure. Spills or domestic effluent release (from camps) and hydrostatic
testing (withdrawal and blowdown of water) can also affect fish health.
4.3.6.5 Impact Analysis
Residual Impacts
Residual impacts of changes to the abundance and structure of aquatic
communities and the survival of endemic species as a result of the slurry pipeline
construction, operation and closure are summarized in Table 4.3-10.
The status of fish species in the pipeline area is poorly understood, and the level
of information on basic biology and life history for most endemic fish species
and other endemic aquatic biota is very limited. Basic biology would better help
define sensitive habitat and sensitive time periods. However, mitigation
