Genomics and Applied Biology 2014, Vol. 4, No. 2, 1-9
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Figure 5
largely by geology since it is highly influenced by
mineral salts (Kalyoncu et al., 2009). However, an
increase in conductivity possibly occurs when additional
wastes containing ions enter the stream section
(Kalyoncu et al., 2009). Thus, it is highly probable
that the increase in conductivity in the stream from
sampling site 1 up to sampling site 2 is due to the
additional waste from charcoal burners as well as
other anthropogenic activities. Conductivity indicated
a positive significant effect on both invertebrate
species abundance and diversity (Table 1). albeit it
showed an imaginary significant effect on species
richness. This shows that high levels of conductivity
favoured both invertebrate species abundance and
diversity (Figure 2).
The pH results indicate that the waters from the
Mwekera stream during the sampling period were
almost natural (Appendix 2). According to Davies and
Day (1998) most natural waters’ pH values range from
6 to 9. This implies that the Mwekera stream has the
capacity to buffer it’s self as indicated by Li et al.,
(2007) that most rivers and streams have a buffering
capacity which affects the rate of change of pH in
aquatic ecosystems as they tend to resist rapid change
of pH especially when the flow is high. However, the
results indicate that pH positively correlated with both
invertebrate species abundance and diversity (Table 1).
The slight decrease in alkalinity from site S1 to S10,
made species abundance and diversity to decrease as
well. According to Bronmark and Hasson (1998)
aquatic insects are extremely sensitive to pH values
below 6. The Gastropods, mayflies, stoneflies and
caddis flies are some of invertebrate groups that prefer
pH levels from 7-9.5, and these were found on site S1,
S2, and S3 which had slightly alkaline conditions.
In this study, water temperatures varied slightly
significantly across sampling sites (appendix 2).
Sampling site S1 recorded the highest temperature
(19.9 ± 0.45
C), while site S6 located in the up
reaches of the stream recorded the lowest temperature
(15.5 ± 0.28
C). High temperatures at site S1 was
caused by the exposure of the stream to the sun,
complete lack of vegetation canopy and heat exchange
with the atmospheric air. In contrast low temperature
recorded at site S6 may, however, be attributed to the
cooling effects of the dense forest canopy. This
observation concurs with study findings by Shivoga
(2001) who found forests to influence the temperature
regime of rivers and their invertebrate communities.
However, the results indicate that water temperatures
did significantly affect invertebrate species abundance
(Table 1). However, no significant relationship was
found between water temperature and diversity,
meaning that water temperature could not explain
diversity patterns in the Mwekera stream. These
results show that as the water temperature increases,
even the number of invertebrates per site increases.
This conclusion is in perfect agreement with the
results found by Davies and Day (1998). Their results
showed that high temperatures within the range of
20-25
C favored invertebrate metabolic and physiological
