Acute toxicity tests on the effects of Gramoxone and detergent (both applied as a single dose) to nile tilapia, Oreochromis niloticus, fingerlings (mean weight 2.7~c1 g) were conducted using static bioassay. The 96-h LC sub(50) of Gramoxone and detergent applied were 0.08ml/l and 0.004 g/l, respectively. The fingerlings showed increased hyperactivities exemplified by erratic movement, loss of reflex, and hyperventilation during the period of exposure. These effects increased with increasing concentrations of Gramoxone or detergent throughout the duration of exposure. Tilapia fingerlings of the same size showed different levels of tolerance to the same concentration of both pollutant

Fagbenro, O.A.

Kayode, A.B.

Nwanna, L.C.

Salami, A.A.

Aquatic Commons

TOXICITY OF GRAMOXONER AND DE I EaGENT TO NILE TILAPIA
(Oreochromis niloticus L.) FINGERLINGS
BY
Amos B. KAYODE, Adekunle A. SALAIVII, Oyedapo A. FAGBENRO and Lawrence C.
NVVANNA
Department of Fisheries and Wildlife, Federal UniversiO) of Technology, Alcure, Nigeria.
ABS I RACT
Acute toxicity tests on the effects of Gramoxone and detergent (both applied as a single dose) to
Nile tilapia, Oreochromis niloticus, fingerlings (mean weight 2.7±1g) were conducted using static
bioassay. The 96-h LC50 of Gramoxone and detergent applied were 0.08m111 and 0.004 g/1,
respectively. The fingerlings showed increased hyperactivities exemplified by erratic movement,
loss of reflex, and hyperventillation during thye period of exposure. These effects increased with
increasing concentrations of Gramoxone or detergent throughout the duration of exposure. Tilapia
fingerlings of the same size showed different levels of tolerance to the same concentration of both
pollutants.
Key Words: toxicity, Gramoxone, detergent, Nile tilapia, Oreochromis niloticus.
INTRODUCIION
Concerted efforts are currently being made to increase fish production just as attempts are also
made to increase crop production through intensive agricultural practices. The latter has resulted in
a large-scale use of herbicides/pesticides such as Gramoxone which is increasing daily (Mason,
1983). Although there are definite advantages in the use of pesticides for increased of crop yield,
their indiscriminate use has been identified as a cause for many previously unexplained fish kills as a
result of run-off effluents diverted into fish habitats (Oloruntuyi et al., 1992; Palanichamy et al.,
1989). Pesticides usually find ways into the aquatic environment either by accident or by delebrate
application into water bodies. Accidental introduction include the run-off in water from treated
land, spray drift during treatment, washing of spraying equipments in waterways and from the air.
The delibrate application may be used to control weeds, intermediate host of human and animal
diseases, protect aquatic crops and the elimination of unwanted fish (Nair et al., 1985).
Various pesticides are used in Nigeria and while information is available on their impact on
rats and man, little information exists on their effects on fishes. Hence there is a need to evaluate
the significance of such pesticides in order to understand the potential havoc of this pesticide if used
persistently. Other sources of aquatic pollution are effluents from laundries and garages which are
regularly discharged into inland water bodies; often resulting in mass mortality, inability to
reproduce in polluted environment and migration to safe areas. The objectives of this study are to
determine the effects and safe limit of Gramoxone or detergent on Nile tilapia (Oreochromis
niloticus) fingerlings.
Materials and Methods
Healthy unsexed O. niloticus fingerlings (2.7±1g) were collected from the Federal University of
Technology Alcure fish farm and acclimated for two weeks and fed with a 40% protein diet prior to
commencement of toxicity tests. They were later stocked into 28 rectangular glass tanks
(75x40x40cm) filled with 45 litres of spring water (pH, 7.2+0.1; temperature, 27.5°C; total'
hardness and alkalinity, 168-213mg/1) and starved for two days. Fish were randomly distributed at
10 fish/tank in duplicated treatments. O. niloticus fingerlings were exposed to graded Gramoxone
59
or detergent concentrations (range 1.0 - 5.1m1/1 and 0.40-0.250, respectively) each treatment
having a control. High dissolved oxygen level was maintained by continous aeration and the tests
were conducted under static toxicity testing conditions (FAO, 1977). Observations of the effects of
Grarnoxone or detergent on fish behaviour were made every six hours. The range of
concentrations used in the tests was predicted to give a mortality range of 0-100% (no mortality -
total fish kills), and the lethal concentration that will kill half of the test population (LC50) was
determined graphically. The data obtained were subjected to the student t-test to determine the
significant differences among means.
Res u Its
The 96-h LC50 of Gramoxone and detergent to O. niloticus were 0.08m111 a.nd 0.004g/1,
respectively (Fig la & lb). Mortality was 85% an.d 100% with 4.51-n1 and 4.8inl. of Gramoxone
while 50% and 75% mortality were recorded with 0.2g and 0.25 g of detergent, respectively. No
mortality was recorded at 0.1g of detergent to the fish. The fish species showed differences in
tolerance to the same concentration of toxicant. Mortality at 4.5ml of Grarnoxone at 96-h was
80% and 90% while the mortality at 0.25g of detergent at 96-h was 70% and 80%. The fingerlings
showed initial disturbed swimming behaviours such as erratic movement, rapid opercula movement
and gasping at th.e surface. This was followed by blackening of the whole body, unusual lethargy
ancl tendency of the fish to settle at the bottom, motionless with slow opercular movement.
Discussion
The 96-h LC50 of Gramoxone and detergent to O. niloticus (0.08m1/L and 0.004g/L, respectively)
were different (lower or higher) than toxicity levels for other fishes. For example, Olorwituyi et al.
(1992) reported 96-h LC50 of 99ppm and 9Oppm for "round up' and Gramoxone exposed to
catfish, Ciarías gartepinus (mean weight 30g) while Cruz et al. (1988) reported 2.58pprn and
0.092ppin for the molluscides, aquation and brestan respectively on O. mossambicus (mean weight
30g). Organisms exposed to chemicals usually exhibited changes in opercular rate which
demonstrated to be a sensitive indicator of physiological stress in fish subjected to sublethal
concentrations of pollutants (David, 1973).
It was observed in this study that O. niloticus fin.gerlings showed variations in their
tolerance of same Gratnoxone and detergent concentrations at a given period particularly as the
replicates giave different mortality. Chen and Lei (1990) reported that juveniles of shrimp, Penaeus
monoclon showed differences in tolerance to ammonia and nitrate solutions. Heit and Fingermann
(1977) noted that females of the cray fishes, Procan2barus clarki and 1-;'axonella elypeata were
much more tolerant of mercury than the males, thus the differences in tolerance of O. niloticus to
the same concentration of Gramoxone and detergent may be attributed to the male female
composition of the test fishes
Stress and hyperactivities of the O. niloticus fingerlings observed in this study, was similarly
reported in the brook stout, Sctivelinus fontinalis (Drummond et al., 1973). Ajao (1985) found
that as the concentrations of the textile mili waste water effluent and detergent wash increased,
some of the hermit crab (Clibinarium africanus) abandoned their shells while some exhausted crabs
had half of their body passively outstretched outside the shell with the antenna lazily probin.g the
test solution. The effects of these pollutants may be less pronounced if effective screening is made
of various chemicals in use, particularly in areas where fish farms are located.
60
REFE CES
Ajao, E.A. (1985): Acute toxicity tests of a textile mill waste water effluent and
a detergent wash with a hermit crab Clibinarius africana
(Aurivillins) Biologia Africana 2: 333-40.
Chen, J. and S. Lei (1990): Toxicity of ammonia and intrate to Penaeus monodon
juveniles. Journal of the World Aquacultural Society 21:
300-306.
Cruz, E.R; M.C. De la Cruz and N.A. Sunaz (1988):
Haematological and Histopathological changes in
Oreochromis mossambicus after exposure to the
molluscidies aquatin and brestan. pp. 99-110, In
Proceedings of the Second International Symposium on
Tilapia in Aquaculture, Bangkok, Thailand.
Davis, J.C. (1973): Sublethal effects of bleached kraft pulp mill effluent on
respiration and circulation in Sockeye Salmon,
(Onéorthyncus nerka) Journal of the Fisheries Research
Board of Canada 30: 369-377.
Drummond R.A; W.A. Spoor and G.F. Oslon (1973):
Some short term indicators of sublethal effects of copper on
brook stout (Salvelinus fontinalis). Journal of the Fisheries
Research Board of Canada 30: 698-701.
FAO (1977): Manual of methods in aquatic environment research, Part 4:
bases for selecting biological tests to evaluate marine
pollution. FAO Fisheries Technical Paper No. 164: 31pp.
Heit, M. and M. Fingermann (1977): The influence of size sex and temperature on the toxicity
of mercury to two species of crayfishes. Bulletin of the
Environmental Contaminant Toxicology 18: 572-580.
Mason, C.E. (1983): Biology of fresh water pollution. Selector Printing
Compound, Singapore. 250 pp.
Nair, G.A.; N. Vijamohan; N.B. Nair and N. Smya (1985):
The growth, good and conversion efficiency of cichlid fish
Sarotherodon mossambicus exposed to lethal
concentrations of effluent from titanium dioxide factory.
Journal Animal Morphology and Physiology 32:43-53.
Oloruntuyi, 0.0,0. Mullero and Odukale (1992):
The effects of two pesticides on Clarias gariepinus pp.
173-177, In: Proceedings of the 10th Conference of the
Fisheries Society of Nigeria, Abeolcuta, Nigeria.
Palanichamy S.S, Arunachalam and P. Baskaran (1989):
Impact of pesticides on protein metabolism in the
freshwater fish Mystus vittatus. Journal qf Ecobiology
1(2): 90-97.
61


Toxicity of Gramoxone super(R) and detergent to nile tilapia (Oreochromis niloticus) L. fingerlings

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Toxicity of Gramoxone super(R) and detergent to nile tilapia (Oreochromis niloticus) L. fingerlings

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