International Journal of Marine Science, 2017, Vol.7, No.29, 284-291
289
Table 1 Water quality parameters of culture system of
Clariasgariepinus
observed over period of 96 hours
Parameters
CONTROL (0 mg/L) TRT 1 (2 mg/L) TRT2 (3 mg/L) TRT3 (4 mg/L) TRT4 (5 mg/L) TRT5 (6 mg/L)
TEMP (°C)
25.53±0.13
ab
25.53±0.09
ab
25.48±0.16
a
25.68±0.68
b
25.48±0.10
a
25.50±0.18
a
pH
6.58±0.16
a
6.48±0.15
a
6.44±0.12
a
6.40±0.07
a
6.44±0.10
a
6.47±0.10
a
D.O (ppm)
4.11±0.22
e
3.08±0.17
d
2.99±0.18
d
2.75±0.28
c
2.27±0.20
b
1.52±0.34
a
SAL (ppm)
0.08±0.00
a
0.08±0.00
a
0.08±0.00
a
0.08±0.00
a
0.08±0.00
a
0.08±0.00
a
COND (mn-cm) 0.0042±0.00
a
0.0043±0.00
a
0.0042±0.00
a
0.0042±0.00
a
0.0043±0.00
a
0.0042±0.00
a
T.D.S (ppm)
95.83±1.10
a
96.00±1.75
a
95.67±2.31
a
95.17±1.80
a
95.17±1.11
a
95.08±1.93
a
Ammonia (ppm) 0.4±0.16
a
0.34±0.15
a
0.33±0.15
a
0.35±0.17
a
0.40±0.15
a
0.33±0.15
a
Nitrate (ppm)
7.08±2.57
a
7.50±2.61
a
6.67±2.46
a
7.50±2.46
a
6.67±2.46
a
7.08±2.57
a
Nitrite (ppm)
1.42±0.51
a
1.33±0.49
a
1.42±0.51
a
1.33±0.49
a
1.42±0.51
a
1.41±0.51
a
Note: Mean with different superscripts are significantly different
3 Discussion
Behavioural responses has been used as indicator of toxic stress in fish (Little et al., 1993); Ololade and Oginni
(2010) reported that behavioural responses may be useful indicators of sub-lethal contamination even at
concentrations being lower than those that affect growth. Fishes in a contaminated environment show some
altered behavioural patterns which may include avoidance, locomotive activity and aggression and these may
cause fish attempt to escape or adjust to the stress condition (Morgan et al., 1991; Gormley and Teather, 2003).
Behavioural functions are generally quite vulnerable to contaminant exposures, and fish often exhibit these
responses first when exposed to pollutants (Little et al., 1993; Ololade and Oginni, 2010). The behavioural
activities of
Clarias gariepinus
juveniles on introduction of selenium at different concentrations were observed.
The noticeable behaviours include aggressiveness, loss of equilibrium, slow motion, erratic swimming and sound
making which is not uncommon because it has been reported by Gormley and Teather (2003) who worked on
Japanese medaka (
Oryziaslatipes
) exposed to endosulfan. Erratic swimming exhibited by the fish could be as a
result of loss of equilibrium caused by the intoxication of the selenium. Opercular movement and loss of
equilibrium observed in this study is similar to the report of Ghatak and Konar (1990) on
Tilapia mossambica
exposed to cadmium. Attempt to escape by the experimental fish especially at higher concentration (5 and 6 mg/L)
is no doubt caused by the toxic substance. This particular behaviour indicates that the environment has become
unsuitable for the fish to survive. Fish may take up selenium through their gills, as selenium accumulation in
rainbow trout is greater after gill development (Hodson et al., 1986). Gill lamellae which are normally thin and
delicate are necessary for gas exchange in respiration. As a result of lamellar necrosis in this study, the function of
the lamellar to increase the surface area for oxygen exchange could not be achieved. Similar results were reported
by Cavan and Muley (2004) when
Cirrhinu smrigala
was exposed to mercury and lead. There were necrotic
change in intercellular epithelial cells, lamellar degeneration and epithelia lifting. Lamellar hyperplasia that was
revealed in this study is also similar to the findings of Olufayo and Alade (2012) that reported hyperplasia at the
secondary gill lamellar after the exposure of
Heterobranchus Bidorsolis
to Cypermethrin concentration. It also
agreed with the finding of Vinodhini and Narayanan (2008) who that expose the organs of
Cyrinus carpio
to
heavy metals. Fish kidney is made up of glomeruli, mesangial cells, podocytes, endothelial and tubular cells, and
both capillary and central veins (which collect and transport urine). In fish, kidney performs an important function
to maintain the homeostasis. The kidney is one of the first organs to be effected by contaminants in water
(Thophon et al., 2003; Mela et al., 2007). Glomerular disease which is associated with toxic substance in the
kidney was revealed in this study and this could be the cause of blood stain on the glomerulus. A clear vacuole
(cytoplasmic vacuolization) was also observed in the renal tubule. Similar report was made by Olufayo and Alade
(2012). Tubular necrosis which is also associated with kidney poison was revealed in the study. This condition
involves the death of tubular epithelia cells that form the renal tubules of the kidney and it could result in the
failure of the kidney to remove waste product and excess fluids. Similar finding was revealed in common carp
when exposed to mixture of heavy metal (Cd+pb+Cr+Ni) (Vinodhiniand Narayanan, 2008). The invisible effect
on the skin structure of fish that were exposed to lower concentration could be as a result of the hardy nature of