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International Journal of Aquaculture, 2014, Vol.4, No.25 1
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7
http://ija.biopublisher.ca
4
Alikunhi (1957) water with alkalinity greater than 100
mg/l is productive and the observed alkalinity values
in the ponds were within limit prescribed for fresh
water fish culture in sewage treatment ponds.
2.2 Zooplankton
In the present study four groups of zooplankton such as,
copepoda, rotifera, ostracoda and cladocera were
observed (Table 2).
Table 2 Zooplankton in the treatment ponds
Parameters
Oxidation
pond 1
Oxidation
pond 2
Stabilization
pond
Copepod
Copepod and Nauplius
++++
++
+++
Rotifera
Brachionus rubens
++
+++
+
B. plicatilis
++
+++
++
B. calicyflorus
-
++
++
Asplanchna
-
++++
++++
Ostrocoda
Eucypris pigra
-
++
++++
Cladocera
Daphnia
+
++
+++
Note:
-
= absent, +=minimum, ++=moderate, +++= abundant,
++++=greater abundance
The copepods and their larval stages constituted a
predominant group in oxidation pond 1 and 3. Ahamad
et al. (2011) reported that rotifers, cladocerans,
copepods and ostracods constitute the major
zooplankton population in the sewage fed fish ponds
and contributed significantly to secondary production
of the ponds. In oxidation pond 1, the copepods and
their naupli were numerically dominant along with the
rotifers,
Brachionus rubens
and
B. plicatilis
. The
rotifera represented by four genera were more
abundant in oxidation ponds 2 and 3. In pond 2 the
rotifers especially
Asplanchna
sp. followed by
B.
rubens, B. plicatilis
and
B. calyciflorus
dominated and
the number of copepods and Daphnia were moderate.
In pond 3, the number of the ostracod,
Eucypris pigra
and the rotifer
Asplanchna
sp. were very high followed
by copepoda, naupli and cladocera. In general, the
number and species of zooplankton were higher in
pond 2 and 3 than pond 1. However, the rotifers were
minimum in pond 1 than 2 and 3 (Table 2). Earlier
studies revealed that a few genera of rotifers and
Ostracoda are capable of withstanding anaerobic
conditions for at least short period (Kownacki, 1977;
Pennak, 1989). The present study also indicated
higher population density of crustacean genera in the
pond 3 where oxygen level was more than the other
ponds. The present results are in conformity with the
statement of Cauchie et al. (2000) that the planktonic
community in the stabilization ponds was composed
of the branchiopods and the cyclopoid copepods.
2.3 Phytoplankton
Phytoplankton population in the sewage oxidation
ponds belonged to the division
Chlorophyceae,
Cyanophyceae, Bacillariophyceae
and
Euglenophyceae
(Table 3). The members of the
Bacillariophyceae
represented with more number of genus (4) than the
other groups. The greater abundance of phytoplankton
was noticed in the oxidation pond 2. In pond 1 the
number of species and their numerical density was
comparatively lower and only
Pondorina, Coelastrum
and
Staroneis
were found in small numbers.
However,
Euglena
and
Phacus
occurred throughout
the study period. In general the phytoplankton
population was minimum in this pond due to the
complete masking of sunlight by the
Eichhornia
plants. In pond 3 the number of
Euglena
and
Phacus
was very high along with the diatoms,
Cyclotella,
Fragilaria
and
Navicula
.
Table 3 Phytoplankton in the sewage pond
Parameters
Oxidation
pond 1
Oxidation
pond 2
Stabilizati
on pond
Chlorophyceae
Pandorina
+
++
+
Micractinium
-
++
-
Coelastrum
+
++
-
Cyanophyceae
Oscillatoria
-
+++
+
Bacillariophycea
Stauroneis
+
++
-
Cyclotella
-
+++
+
Fragilaria
-
+++
+
Navicula
-
++
+
Euglenophyceae
Euglena
+
+++
+++
Phacus
+
++
+++
Note:
-
= absent, + =minimum, ++ =moderate, +++ = abundant,
++++ greater abundant