Intl. J. of Mol. Evol. and Biodivers. 2015, Vol. 5, No. 5, 1-9
4
and to assess whether invertebrates can be used to
monitor changes in water quality in the Mwekera
stream using min-SASS.
This study aimed at assessing the effect of water
quality which is driven by many physical, chemical
and biological parameters introduced by natural forces
and human (anthropogenic) activities on invertebrate
species diversity in the Mwekera stream. More
importantly, the study provided the only best way to
monitor the health of the stream and measure the
general quality of the water flowing into the National
Aquaculture Research and Development Center
(NARDC) at Mwekera using mini-SASS. Also it
provided a good understanding of the factors that
affect water quality status of the stream and finally the
fish farm, for effective management as well as for
conducting environmental impact assessment.
4.0 Results
During the study period, a total of 106 individuals
were sampled and identified, mainly in twelve
invertebrate orders in the Mwekera stream. Decapoda,
Tricoptera, Plecoptera, Coleoptera, Diptera, Gastropoda,
Oligochaeta, Turbellaria, Hemipetera, Emphemeroptera,
Hirudinea and Odonata. Generally, cross sampling
sites pH and conductivity differed significantly, while
temperature and redox were similar (Appendix 2).
Effect of conductivity on invertebrate species
abundance, richness and diversity
The mean invertebrate species abundance, richness
and diversity were 12.5±2.43; 2.9±0.41; 0.79±0.11
respectively. Generally, across sampling sites significant
differences occurred in abundance (F=18.16;
P
=0.028);
richness (F=3.18;
P
=0.01) and diversity (F=4.91;
P
=0.05). However, conductivity was significantly
related to diversity and abundance (Figure 2; Table 1).
But species richness remained unaffected (Table 1).
Effect of pH on invertebrate species abundance,
richness and diversity
Across sampling sites, the mean invertebrate species
abundance, richness and diversity varied significantly.
However, the results show that pH was significantly
related to abundance and diversity (Figure 3; Table 1).
but with imaginary significance to richness (Table 1).
This basically suggests that abundance and diversity
increased with increasing alkalinity levels.
Effect of temperature on invertebrate species
abundance, richness and diversity
The mean invertebrate species abundance, richness
and diversity were 12.5±2.43; 2.9±0.41; 0.79±0.11
respectively. Across sampling sites they all differed
significantly: abundance (F=4.91;
P
=0.028); richness
(F=3.18;
P
=0.01); diversity (F=4.91;
P
=0.05). However,
the results show that temperature had a significant
effect on the abundance of invertebrates (Figure 4;
Table 1). but with an imaginary significant effect on
diversity (Figure 4; Table 1)
Effect of redox on invertebrate species abundance,
richness and diversity
The mean invertebrate species abundance, richness
and diversity were 12.5±2.43; 2.9±0.41; 0.79±0.11
respectively. Generally, across sampling sites significant
differences occurred in abundance (F=18.16; P=0.028);
richness (F=3.18;
P
=0.01) and diversity (F=4.91;
P
=0.05). However, the results show that there was no
significant relationship between redox and the response
variables (Table 1). Generally, this suggests that
increasing redox levels in the stream had no effect on
the distribution of invertebrates along the stream.
(Figure 5)
Anova table 1
Explanatory
variable
Abundance
Richness
Diversity
numDF denDF F-value Pr (
F) numDF denDF F-value Pr(
F) numDF denDF F-value Pr (
F)
Conductivity
8
10
0.01
0.01
8
10
3.84
0.08
8
10
5.80
0.04
pH
8
10
25.32 0.001
8
10
3.55
0.09
8
10
5.60
0.04
Temperature
8
10
5.77
0.04
8
10
0.49
0.53
8
10
4.39
0.06
Redox
8
10
0.81
0.39
8
10
0.89
0.37
8
10
3.00
0.12
