Intl. J. of Mol. Evol. and Biodivers. 2015, Vol. 5, No. 5, 1-9
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Forestry College (ZFC) and to the local people in
Mwekera. However, due to high deforestation
activities in Mwekera national forest, the stream has
been exposed to land erosion. Most of the eroded
materials from the upper land are deposited into the
Mwekera stream and dam causing siltation. As a result
of this, the water quality has been affected in the
stream and the dam which is the only water source for
the named institutions. This basically, has contributed
to a high degree of spatial and temporal variability in
the aquatic fauna. The Mwekera stream has a diverse
array of invertebrate habitat elements (such as littoral
grass, aquatic macrophytes, algae, overhanging and
submerged vegetation, woody debris, leaf litter and
root masses) and the substrate composition is comprised
mostly of mud, sand, cobbles and gravel. Registered
air temperatures in the study area vary between
24.0
⁰
C and 36
⁰
C (Nyambe and Feilberg, 2009).
Freshwater ecosystems in Zambia are relatively
isolated and physically fragmented within a largely
terrestrial landscape. They are vulnerable to many
physical, chemical and biological parameters introduced
by natural forces and human (anthropogenic) activities.
A study by Tesfaye (1988) indicated that invertebrate
composition and abundance varied along streams as
pollution gradient increased. This clearly indicates
that invertebrates in Zambia could be good evidence
for developing bio-assessment methodology especially
using invertebrate as indicators. Furthermore, most of
the European researchers use non-systematic units
such as fish, macrophytes, phytoplankton and diatoms
for regular observations and determination of ecological
statuses of the streams (De Pauw and Vanhooren,
1983). Among which the most frequently used
community to determine the water quality in the
streams are the invertebrates. However, such study is
lacking in Zambia. Thus, this study was conducted to
assess influence of water quality on the diversity and
distribution of invertebrates in the Mwekera stream.
The relationship between physio-chemical
parameters and invertebrates
According to the study conducted by Uyanik et al.,
(2005) on the relationship between invertebrates and
water quality parameters, such as conductivity, pH,
and dissolved oxygen (DO), in a river in Turkey. This
study was carried out in order to assess the ecological
impact of wastewater discharge into rivers. The kick
sampling method was used in collecting benthic
macro-invertebrates. The researchers used the Biological
Monitoring Working Party (BMWP), Trent Biotic
Index (TBI), and Chandler Score to quantify the
conditions of the biota at the study sites. The results of
their study supported its hypothesis that the use of
invertebrates as indicators in a water body is an ideal
methodology for the assessment of the water quality.
Physico-chemical parameter and invertebrate indicator
were both effective in assessing the quality of the
water. However, the use of both of these indicators
together may have significant relationship and have
more accurate results.
George et al. (2009) studied the benthic invertebrate
fauna and physico-chemical parameters in Okpoka
creek sediments for a period of one year. They found
out that the distribution pattern of the invertebrates in
all the stations of the creek did not show major
differences. Their results also showed strong relationship
between the physico-chemical quality and the
distribution of organisms along the creek they have
studied. Another study was conducted by Sharma and
Chowdhary (2011) using both abiotic and biotic
indicators. The relative diversity, species richness,
dominance, evenness indices, physico-chemical
parameters and percentage of Annelida + Arthropoda
+ Mollusca (AAM) individuals were determined.
Significant relationships were recorded between
physico-chemical parameters and the occurrence of
specific genera. They concluded that the changes in
invertebrate assemblages were primarily due to
changes in water quality.
River pH
Rivers show regional differences in pH due to
differences in geology and hydrology of the catchment
area, input of acidifying substance, and productivity
of the system, but the pH in the majority of streams on
earth is between 6 and 9 (Bronmark and Hasson,
1998). One of the most significant environmental
impacts of pH is involvement on synergistic effects.
For example, very acidic water can cause heavy
metals, such as copper and aluminum to be released
into the water. The pH value of a stream mainly
