International Journal of Aquaculture, 2013, Vol.3, No.10, 43
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48
http://ija.sophiapublisher.com
46
Table 2 AAcute toxicity results obtained from both inlet and outlet effluent concentrations for
Oreochromis niloticus
Souurce of Effluent
96
hrs LC
50
(%)
96
hrs ATU
Efficiency (%)
Safe concentration (%)
Inlet
30.5
3.279
3.05
Outlet
71.5
1.399
7.15
Inlet/Outlet
-
-
57.33%
-
2
Discussion
The present findings confirmed that water quality
parameters were affected by effluent concentration. As
indicated by Figure 1, Figure 2 and Figure 3. The
content of dissolved oxygen concentration was decreased.
While pH values and conductivity were increased as
the textile effluent concentration increased. This implies
that the values of water quality parameters alter as
effluent concentration changed. As a result of this. The
behavioural responses of aquatic organisms were
affected negatively and led to reduce fitness to the
environment. And eventually death occurred. This is
because water quality parameters such as pH, dissolved
oxygen concentration, conductivity and water temperature
are some of the most important limiting environmental
factors that could affect the behavioural response.
Growth rate and survival rate of aquatic organisms
such as
Oreochromis niloticus
(
Aslam et al., 2004;
Noor et al., 2010; Kassaye, 2012). The present
results confirmed that active behavioural responses
of
Oreochromis niloticus
was observed at lower
effluent concentration. While erratic swimming
behaviour, gasping and frequent surfacing were
observed on those fish stocked in higher effluent
concentrations particularly the fish stocked in 30%,
40%
and 100% (v/v) effluent concentrations. As the
experiment progressed, the activity of those fish were
decreased. Even they were collapsed to swim,
particularly for the fish found in 40 and 100% (v/v)
effluent concentrations. This result is in line with the
works of Ogugbue and Oranusi (2005) and Dahunsi
and Oranusi (2012) who reported that as effluent
concentration increased. the activities of the fish is
affected negatively. It was also noted that the fish
stocked at higher effluent concentration had had three
phases of behavioral responses. namely: active.
fatigue and collapse.This result was in line with the
findings of Adewoye et al. (2005) and Soni et al. (2006)
who reported that erratic behavioural responses of the
test organisms were resulted from high concentration of
toxicants found in the industrial effluent. As the authors
reported that as the experiment progressed, erratic
behavioural response of the test organisms was
reduced, and eventually they stopped swimming. This
implies that the test organisms were not tolerated
high effluent concentrations. Similar results were
reported by Dahunsi and Oranusi (2012). Odjegba and
Bambgbose (2012). And Roopadevi and Somashekar
(2012).
They stated that when test organisms
stocked in higher effluent concentration for longer
period. The homeostasis behaviour of the fish was
disturbed, this eventually led to death, which is
confirmed by the present results.
In the present experiment, mortality was occurred on a
daily basis. In the first day of the experiment, the fish
stocked in 30%, 40% and 100% (v/v) of the inlet
effluent concentrations and 40% and 100% (v/v) of
the outlet effluent concentrations were died. For lower
concentration. 30% (v/v) of the outlet effluent
concentration. Death was occurred from day two onward.
In line with the present results. Movahedian et al. (2005)
reported that immobility and mortality of the test
organism (
Daphnia magna
)
is increased as concentration
increased on daily based. Similarly. 50% of the test
organisms were died within 24hrs for 100% (v/v) inlet
effluent concentration and 72hrs for 40% (v/v) inlet
effluent concentration and 100% (v/v) outlet effluent
concentration. These results clearly indicate that the
treatment ponds are effective to remove some of the
toxicants that are discharged for the textile industry.
The present results also revealed that the 96hrs LC
50
values for both inlet and outlet were 30.5% (v/v) and
3.279
as ATU for inlet. and 71.5% and 1.399 as ATU
for outlet. This result implies that
Oreochromis
niloticus
is susceptible to textile effluent or the
effluent is very toxic even after treatment. The safe
level for inlet and outlet effluent concentrations is set to
be 3.05% (v/v) and 7.15% (v/v). This result is in line
with the work of Dahunsi and Oranusi (2012). Who
reported that the 96hrs LC
50
for
Clarias gariepinus
was found to be 35.518% and 2.5 as ATU of synthetic
resin effluent. The present results are also in line with
the work of Chude and Ekpo (2010) who reported that
Oreochromis niloticus
is more susceptible than
Clarias gariepinus
.