Intl. J. of Mol. Evol. and Biodivers. 2015, Vol. 5, No. 5, 1-9
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activity and life processes such as feeding, reproduction,
movements and abundance.
Redox potential which is used to indicate the presence
of oxygen, showed no significant variation across sites
(Appendix 2). However, the results revealed that
redox correlated negatively with both invertebrate
species abundance and diversity. These results suggest
that the redox levels were therefore not a limiting
factor to the diversity of invertebrates along the
Mwekera stream at the time of sampling. This is
supported by Chapman (1996) who observed that it is
at levels below 100mV that the survival of biological
communities will be affected, thus changing diversity
structure. So, the lack of significant relationship in
this study may be due to the oxygen levels, as their
significance to aquatic biota depends on the frequency,
timing and duration of depletion.
South Africa scoring system index (Mini-SASS)
An indication of the quality of each sampling site was
obtained using the Mini-SASS scoring system version
5 (Chutter, 1998). Many of the invertebrate taxa
collected from the Mwekera stream were sensitive to
water quality change. Using SASS5 score, the range
was between 5 and 27 which were from site S5 to site
S2 respectively (Appendix 3). ASPT (average Score
per taxa) scores ranged from 2.5 to 7.3 at site S5 and
S1 respectively as shown in Appendix 3. The water
qualities for site S2, S3, S4, S6, S6, S7, S8, S9, and
S10 were classified to be fair, except for site S1 and
S5. The water quality for site S1 was classified to be
excellent, suggesting a number of sensitive invertebrate
species were present. Site S5 was classified to be poor,
meaning that it had the most deteriorated ecosystem
health than all the sites, and the invertebrate species
present there were tolerated. These findings from the
mini-SASS results have generally offered a more
holistic approach, based on the recognition that
monitoring of physico-chemical water variables only
is not sufficient to achieve integrated ecosystem
monitoring.
Mini-SASS was the only available tool at the time of
carrying out this study; however Lang et al., (2013)
and Lowe et al.,
(2013) have since developed a
Zambian water monitoring protocol (ZISS) for use in
stream water quality assessment built on the
min-SASS framework. The Zambian Invertebrates
Scoring System (ZISS) uses the identified macro
invertebrates to score for the water quality of any
given fresh water locality in Zambia.
Materials and Methods
Study site
This study was performed in Mwekera stream, a first
order perennial stream (12º52'N and 28º16' 0"E)
located in the south-east part of Kitwe on the
Copperbelt province. The study area is a tributary of
the Kafue River and is at an elevation of 1,158 meters
above sea level. From its origin the stream flows
downstream through a natural forest dominated
mainly by indigenous trees. In the lower reaches it
passes through the National Aquaculture Research
Development Centre before it eventually coalesces
with the Kafue River. Along its water course
especially in its up reaches, the stream is dominated
by indigenous trees and other riparian vegetation that
include the following:
Brachystegia
,
Julbernadia
and
Isorberlinia.
The National Aquaculture Research Development
Centre (NARDC) was established in 1994 for fish
propagation that included developing techniques for
the mass production of fingerings, fish feed formulation
and assessing the pond environment. The quality of
the water upstream is therefore of great importance to
the Centre as the immediate end user before it gets to
the Kafue river further downstream. (Figure 1)
Figure 1 The map of study area with marked sampling sites
