Clayton Falls Project Water Use Plan Aquatic - BC Hydro

Clayton Falls WUP Aquatic Productivity Monitoring Program – Year 1, 2005
Invertebrate Taxonomy Results (February 26, 2006)
Upon preliminary sample assessment by taxonomists it was determined species identification
would be completed on all samples collected at Reach 2 (six samples, February 26, 2006).
Owing to limited numbers of specimens collected in the sample baskets it was well within the
scope and budget of the project to complete taxonomic identification of specimens from all six
samples from Reach 2 (Site CF1); however, it was not considered that there was enough data
for full taxonomic assessment (e.g., species density, life stage use, etc.).
Aquatic invertebrates were identified to species where possible. Identification to species level
was contingent upon the life stage of the nymph or larva. Mature larvae in their final stage(s) of
development are typically most readily identifiable to species level. Earlier stages (instars) in
those samples collected were identified to Genus level. In some cases (e.g., caddis, blackfly
and Chironomid larvae), specimens were identified to Family level. Refer to the attached
PowerPoint document for photographs of all aquatic invertebrates collected as well as a typical
sample site.
The three primary aquatic insect Orders Ephemeroptera, Plectoptera, Trichoptera (May, Stone
and Caddis flies) most often associated with fish habitat utilization were represented in samples
taken from Clayton Creek. Representatives from the Dipteran Order (i.e. Simuliids; Blackfly
larvae and Chironomids; non-biting Midge larvae) were also recorded.
All specimens collected were in various stages of development. The variance was due to
emergence times of particular species. It was noted a stonefly such as Zapada cinctipes, which
is generally in the “winter stonefly” group, would be expected to be mature in development in
Late February, and subsequently was recorded as such in specimens sampled. Mid to late
spring emerging insects such as the mayflies Rithrogena sp., Ironopsis grandis, Cinygmula sp.
and Ameletus sp. were in intermediate stages of development as would be expected at the
sample period (late February).
The presence of such species as Cinygmula sp., Ironopsis grandis and Rithrogena sp.,
mayflies as well as stonefly specimens typically indicates good water quality, since these
aquatic invertebrates are often the first to disappear when such stressors as high water temp.,
low oxygen and toxins are present.
Generally the composition and diversity of specimens observed from the Clayton Creek
samples indicated a relatively diverse benthic invertebrate population; however, quantitative
data could not be assessed or inferred from samples collected.
Collection methods were problematic for invertebrate collection in Clayton Creek. The planted
baskets were undersized and limited sample substrate size. This may have limited colonization
(in terms of species diversity and numbers) within the basket for aquatic invertebrates as the
substrate in this stream reach is comprised predominantly of cobble and boulder, which is much
more stable as refuge when compared to the planted baskets.
Kynoch Resources
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