Environmental Assessment
Volume C-4.3
Slurry Pipeline
Fish and Aquatic Resources
Ambatovy Project
118
January 2006
impact (sensitivity to construction), accessibility and location along the pipeline
route. Based on the habitat condition, professional judgement of potential
ecosystem sensitivity to construction from and accessibility, a representative
sample of drainage types at the potential watercourse crossings was selected from
the reconnaissance data for subsequent detailed site assessments.
Detailed sampling for fish, aquatic invertebrates, aquatic macrophytes and
general habitat characteristics was completed at 15 stream/river locations in the
pipeline local study area (LSA). Field surveys were conducted primarily during
the dry season (low flow) in September-October 2004 at which time 13 sites
were sampled. Two additional sites, excluded from the dry season survey due to
logistic difficulties, were sampled during a supplemental wet season (high flow)
survey in January 2005.
Aquatic Habitat
A detailed habitat characterization based on instream characteristics, including
channel width, depth, flow rate, dominant substrate types and cover, was
completed to quantify habitat type at each site. In-situ water quality (pH, total
dissolved solids (TDS), temperature and, dissolved oxygen) was also determined
at each site. In addition, the Intermediate Habitat Integrity Assessment (IHIA)
model (Kemper 1999) was used to describe and quantify habitat characteristics.
Fish
Fish samples were collected using a variety of techniques in order to sample all
habitat types used by the resident fish species. Electro fishing, seine nets and gill
nets were the primary methods of capture. Except for voucher specimens
retained for confirmation of identification, all other fish were released alive after
recording basic life history data (i.e., length, weight, etc.). Preliminary
identification to species level was done by the Biology Department, University of
Antananarivo. Confirmation of these identifications is in progress at the
American Museum of Natural History and the New York Aquarium and
therefore the assessments based on species identifications within the following
material are provisional.
Macro-Invertebrates
Aquatic macro-invertebrates were collected using a quantitative (USEPA 1998)
and qualitative (Dickens and Graham 2002) approach to ensure collection of
community information from all habitats. Representative samples were
preserved in 90% ethanol for subsequent identification. Macro invertebrates
were identified to the family or genus levels. Similar to the fish fauna,
preliminary identification of macro-invertebrates conducted by personnel at the
