Annual report 2006-2007 - Taranaki Regional Council

mayflies, elmid beetles, Archichauliodes dobsonfly, Hydrobiosis, Pycnocentrodes and
Costachorema caddisflies and Aphrophila cranefly); and four ‘tolerant’ taxa (oligochaete
worms, Aoteapsyche caddisfly, and Maoridiamesa and orthoclad midges), generally similar to
taxa characteristic of upstream sites. Few significant differences in individual taxon
abundances between adjacent sites (F and G) were evident, and despite increases in the
abundance of some ‘moderately sensitive’ taxa (Table 3), and a decrease in abundance of
some ‘tolerant’ taxa, there was little difference in the SQMCIs score at this site, compared to
site F (and most other upstream sites). The SQMCIs value of 5.4 was significantly higher than
the median of previous scores at this site (Table 2), which was indicative of no recent
impacts of the power station's discharges on the macroinvertebrate community of the
Kahouri Stream.
MCI value
140
120
100
80
60
40
20
0
Number of taxa and MCI values in the Kahouri Stream 80m d/s
Stratford CC pow er station discharge (KHI000465)
Jan-88
Jan-89
Jan-90
Jan-91
Jan-92
Jan-93
Jan-94
Jan-95
Jan-96
Jan-97
Jan-98
Jan-99
Jan-00
Jan-01
Jan-02
Jan-03
Jan-04
Jan-05
Jan-06
Jan-07
MCI value M edian M CI to date
No. of taxa M edian no. of taxa to date
Figure 9 Number of taxa and MCI values in the Kahouri Stream at site G (KHI000465)
The MCI was also very similar to that recorded upstream at site F, indicating that any
differences in communities between these two sites were more associated with subtle
changes in the abundance of individual taxa rather than the increase or decrease in numbers
of ‘sensitive’ taxa between sites. A moderate proportion (55% of taxa richness) of ‘sensitive’
taxa were present at this site, slightly less what was present in the nearest upstream (site E)
community.
Site N: Kahouri Stream (KHI000480)
This lower catchment site, located a further 1.4 km downstream, immediately upstream of
the confluence with the Piakau Stream, had a moderately high community richness of 29
taxa. This was higher than the median richness recorded by previous surveys (Table 2 and
Figure 2) and richnesses found at the nearest and all other upstream sites.
Two ‘highly sensitive’ taxa (indicative of good water quality conditions) were present at this
site, one of which was abundant (Deleatidium mayfly). Other taxa characteristic of this site’s
community (Table 3) included six ‘moderately sensitive’ taxa (Coloburiscus and Austroclima
mayflies, Archichauliodes dobsonfly, elmid beetles, Hydrobiosis caddisflies and eriopterini
cranefly), and four ‘tolerant’ taxa (oligochaete worms, Aoteapsyche caddisfly, orthoclad and
Maoridiamesa midges); most taxa similar to the characteristic taxa at the other five upstream
sites.
12
70
60
50
40
30
20
10
0
No. of taxa