International Journal of Aquaculture, 2018, Vol.8, No.11, 77-89
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1.2 Range finding test to find sub-lethal concentration
1.2.1 Preparation of 2, 4-Dimethyl Amine
In computing the amount of pesticides needed in this experiment, the following formula was used:
Where V = volume of water in the aquarium (30 L)
CF = conversion factor (=1.0 mg/L)
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 = 100/WP value)
1.2.2 Observation of water quality parameters
Temperature: Mercury in glass thermometer was used to measure temperature. The thermometer was inserted in
the aquarium for a period not less than three minutes, it was removed and the Mercury level in the glass was read
off as the temperature of the water in °C. Dissolved Oxygen concentration was measured electronically using 970
JENWAY DO
2
meter (made by BIBBY scientific Ltd., UK) to the nearest 0.1 mg/L. pH: pH was also measured
using electronic method. The pH meter model 3505 JENWAY (made by BIBBY scientific Ltd., UK) was used to
determine the pH. The Conductivity was measured using a DDS-307 conductivity meter.
1.2.3 Biological and behavioural parameters
At the start, the fish were monitored to observe their behaviours every 30 minutes. Interval of observation was
increased to every one hour after 12 hours for the remaining period of the range finding experiment. Death fish
were immediately removed and preserves in formaldehyde (Ayoola and Ajani, 2008). A fish was said to be death
when it could not respond to external stimulus. Behavioural characteristics that were watched out for included;
erratic swimming, air gulping, rate of operculation, death, loss of balance, excessive mucus secretion, tail
movement, moulting and barbell deformation (Ada et al., 2017).
1.3 Haematological analysis
Haematological analyses were done by the use of computerized, automated hematology analyzer (sysmex
kx-21N™) (Ada et al., 2016). Although Baker et al. (2001) argued that the manual method is preferred; the
manual method is also not devoid of human errors. This computerized method is fast and remove the problem of
waiting to analyse the samples and parameters one after another. This can lead to changes in the samples.
2 Results
The LC
50
24 hours (22.5 mg/L), 48 hours (18.0 mg/L), 72 hours (16.5 mg/L) and 96 hours (15.0 mg/L) of
Clarias
gariepinus
sub-adults exposed to 2, 4-Dimethyl Amine were shown in Figure 1. Changes in total white blood cells
counts (Figure 2) were observed to be statistically different among one another (α=0.05). But Lymphocytes counts,
Blood protein concentrations (g/dl), ESR (%) and Granolocyte counts also (Figure 3; Figure 4; Figure 5 and
Figure 6) respectively did not have significant differences between mean values (α=0.05). Concentration of
haemoglobin (g/dl) (Figure 7) was statistically the same. Haematocrit (%), plasma albumen and mean platelet
volume showed no significant difference between treatments (Figure 8). But there were significant difference
among means in Mean cell volume (fl), Mean cell haemoglobin (pg), Mean cell haemoglobin concentration (g/dl)
Platelet counts (Figure 9; Figure 10; Figure 11; Figure 12). Physicochemical properties of water exposed to
different concentrations of 2, 4-Dimethyl Amine during acute toxicity assay of
Clarias gariepinus
showed that
conductivity was different among treatments (Table 1). Means of parameters as dissolved oxygen, temperature
and pH were not statistically different. Table 2 expressed the LC
50
24 hours, 48 hours, 72 hours and 96 hours as
well as the safe concentrations for these periods of time. The behavioral and biological responses of the fish to the
toxin were shown in Table 3.
