Basic HTML Version
International Journal of Aquaculture, 2014, Vol.4, No.25 1
-
7
http://ija.biopublisher.ca
2
Campylobacter
sp.
(Gerba, 1983; El-Motaium et al
.,
2000). There is an inverse relationship between
flagellates and ciliates within activated sludge. A large
population of flagellates in the ponds indicate an
overload of sludge while the presence of ciliates shows
that the treatment system is functioning properly. The
invertebrate fauna which depends on the plankton as
food in sewage treatment ponds attract wildlife. More
number of invertebrate species in sewage ponds is
associated with high algal productivity (Wallace and
Merritt, 1980; Richardson, 1984). In certain systems
abundance of invertebrates has also been attributed to
paucity of insect predators (Brightman and Fox, 1976;
Williams, 1985; Dodson, 1987). However, the sewage
water drained into rivers without treatment in many
developing countries leads to spreading of diseases,
increase in biological oxygen demand and
eutrophication (Dicicco, 1979; Sahset et al
.,
2006)
resulting in unsuitable habitat for the inhabitants
(Reynolds, 1997; Calijuri et al., 2002).
Aquatic macrophytes grown on sewage ponds act as
bio-filters, removes pollutants like nitrogen,
phosphorus, pesticides, phenols and heavy metals,
thereby improving the quality of the water. The
presence of water plants like
Eichhornia crassipes,
Alternanthera phyloxiroides
,
Pistia stratiotes
etc. can
bring changes in the nutrient dynamics significantly by
hampering algal photosynthesis resulting in reduced
dissolved oxygen. However, this condition favors the
release of nitrogen and phosphorous from sediments
which may further aid the rapid growth of
macrophytes (Gutierrez et al
.,
2001; Masifwa et al
.,
2001; Sche
ff
er et al
.,
2003).
Aquaculture in waste water is one possible means of
water renovation, environmental protection and food
production, which has been practiced in some
countries for a long time (Allen and Hepher, 1976;
Gaigher, 1983). Pillay (1973) also emphasized the use
of domestic waste water for highly profitable fish
culture. The yield of fish from the sewage effluent fed
ponds was reported to be higher than culturing in
freshwater (Sharma, 1983; Solamalai et al
.,
2003). A
wide variety of fish have been cultured in sewage
treated ponds including carps, tilapia
(Oreochromis
spp.), milkfish (
Chanos chanos
)
,
catfish (
Pangasius
spp.
) and barbs (
Puntius gonionotus
). Okoye et al
.
(1986) reported that the stocking of common carp
(
Cyprinus carpio
) and tilapia (
Sarotherodon galilaeus
)
in sewage fed ponds resulted good production in New
Bussa, Nigeria. Edwards (1990) reviewed the practice
of fish culture in sewerage ponds where the aquatic
macrophytes serve as food for herbivorous fishes.
Considering the above findings the present study was
undertaken to evaluate the physico-chemical
parameters and the biocenosis of water in the sewage
treatment ponds at Ambo university campus for fish
culture.
1 Materials and Methods
There are seven sewage treatment ponds present in the
Ambo University campus from which three oxidation
ponds were selected for the present study. The ponds
are constructed with stone pavement on the sides and
interconnected by filter gates. One of the oxidation
pond’s surface was covered by the water hyacinth,
Eichhornia crassipes.
Water samples from the oxidation ponds were
collected on three consecutive weeks for determination
of physico-chemical parameters such as temperature,
pH, conductivity, alkalinity, chloride, dissolved
oxygen, and carbon dioxide. The surface temperature,
pH and conductivity were measured using digital
probes at the site. Dissolved oxygen, carbon dioxide,
alkalinity and chloride contents were estimated in the
laboratory by following standard methods (Strickland
and Parsons, 1972; APHA, 1998). Plankton samples
were collected using a plankton net made of No.20
bolting silk. The samples were fixed in Lugol’s Iodine
for identification and enumeration of phytoplankton
and zooplankton (Edmondson, 1959). The benthic
macrofauna were collected, identified and counted.
Total heterotrophic bacteria and certain pathogenic
bacteria were enumerated using different selective
media, isolated and identified by following the
method described in FDA BAM (1998).
2 Results and Discussion
2.1 Physico-chemical parameters
Temperature is one of the most important ecological
factors which control behavioral characteristics of
organisms, solubility of gases and minerals in water.
The water temperature in the ponds varied from 18 to
22° C(Table 1). The average temperature in the
oxidation ponds 1, 2 and 3 were 18.33°C and 20.5°C
and 21.83°C respectively. The reduction in temperature