International Journal of Aquaculture, 2013, Vol.3, No.11, 49
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52
damaged cells could be lysed by lysosomal enzymes
immediately thereby causing reduction in liver weight.
The fish therefore remains the most vulnerable group
of aquatic organism to pesticides and particularly
Butachlor (Wany et al., 1992; Tilak et al., 2006). So
its effect on the liver as a component of the gut is not
surprising.
Ou et al. (2000) showed that Butachlor fasten liver
cells formation. The high rate of liver cell formation
may not be followed by regulation of the process,
thereby preventing normal tissue arrangement and
normal function. Butachlor can induce apoptosis both
at molecular as well as cytological level (Ateeq et al.,
2006).
This unprogrammed cell death could be
accountable for tissue degeneration. Ateeq et al. (2002)
pointed out that Butachlor is a spindle fibre inhibitor
which may therefore produce liver cells with
abnormal sets of chromosomes. Such abnormal
structures lead to abnormal physiological functions
that are likely to stress the fish to death.
The hepatosomatic index was observed to be
reducing with increasing Atrazine concentration.
Ogunji et al. (2008) made similar observations when
they substituted 40% of fish meal with dried distillers
grains that hepatosomatic index reduced compared to
control. Similarly, Gomex-Marquez et al. (2003) noted
that hepatosomatic index has an inverse relationship
with gonadosomatic index in
Oreochromis niloticus
.
However, Lim et al. (2007) recorded that they could
not find any change in the hepatosomatic index of
Oreochromis niloticus
exposed to different concentrations
of vitamins C and E. But, increased concentrations of
these vitamins in water increased their concentrations
in the liver. Uchida et al. (2003) reported a reduction
in the hepatosomatic index, condition factor as well as
specific growth rate in the Nile tilapia that fasted for
two weeks. Inability of fish to eat in the presence of
xenobiotics is likely to cause similar reduction in
liver weight and gonad weights. The use of
herbicides around aquatic environment should be
discouraged as they have deleterious effects on
aquaculture production.
3
Materials and Methods
Plastic aquaria of 52 cm length, 38 cm width and 30 cm
height were filled with stream water up to 20.3 cm
level giving a volume of 40 litres of water per tank.
These were subjected to five different concentrations
of the pesticides namely, Glyphosate (Round up),
Paraquat (Gramoxone), Butachlor (Rizene) and Atrazine.
Each herbicide had concentrations labeled T0, T1, T2,
T3, T4, T5 and T6 as described by Beitlich (1995),
FAO (1997) and Martins et al. (2008). The concentrations
were sub lethal, which is lower than their LC50,
earlier determined by Ada (2011). T0 had zero
concentration of pesticides and served as control. Ten
fish specimens were selected randomly and stocked in
each aquarium (APHA, 1981; Cengiz et al.,
2001;
Adeyemo, 2005; Ayoola, 2008). A static bioassay
method was used. These experiments were replicated
three times (Ayoola, 2008) for each concentration and
for each chemical treatment. The formula for computing
the amount of pesticides needed was:
V.CF.ppm/ Al (Decimal) = weight of chemical
(
Beitlich, 1995).
Where V = volume of water in the aquarium.
CF = conversion Factor.
PPM = the desired concentration of chemical/ pesticides
required in.
The aquaria expressed as part per million.
AI = active ingredient, strength of chemical expressed
as a Decimal (100 divided by % active).
Oreochromis niloticus
specimens of size 5 g~14 g
were obtained from Department of Fisheries and
Aquatic Sciences Fish Farm. The sub-adults were used
because gonad size and form changes with age, sex
and period of spawning. The fish were fed for fourteen
days and slaughtered at the end of the experiments.
The fish, gonads and liver were weighed. The liver
and gonads were removed and weighed using a digital
balance (Scout-pro SPU402) for the liver and
electronic balance (EB-3200D, Shimadzu Corporation,
Kyoto, Japan) for gonads and whole fish. The
gonadosomatic index and hepatosomatic index were
obtained by dividing the weight of the gonads and
liver respectively by the total weight of the fish
(
Koumi
et al., 2008) expressed as percentages
(
Gomex-Marquez et al.,
2003).
Five fish were
randomly selected and measured in each tank and their
averages taken.
The hepatosomatic index and gonadosomatic index