International Journal of Scientific & Engineering Research Volume 4, Issue3, March-2013 1

ISSN 2229-5518

Acute Toxicity And Behavioural Changes On African Catfish (Clarias gariepinus ) Exposed To Dizensate (Glyphosate Herbicide)

A.M. AKINSOROTAN, S.A.A. ZELIBE & N.F. OLELE

ABSTRACT: The acute toxicity of Dizensate Glyphosate (N-phosphonomethyl glycine) to Clarias gariepinus adult was conducted using static bioassay under laboratory conditions. The four days median lethal concentration (96 hours LC50) was determined as 43.65mg/l. Mean mortality was 0, 17, 33, 50 and 83% in the concentration of 19.2, 28.8, 38.4, 48.0 and 57.6mg/l respectively, while there was no mortality in the control treatment. There were significant differences (P<0.05) on the effect of concentrations on the fish. Fish response to the toxicant include erratic movement, air gulping, loss of reflex, molting, barbell deformation and excessive mucus secretion. Mortality increased with increase in concentration of Dizensate glyphosate and time of exposure. The physicochemical parameters also showed a slight increase as the concentration increased. It could be concluded that Dizensate glyphosate; an aquatic herbicide, has harmful effects on the behavioral, physiology and biochemistry of catfish which in turn affects the growth rate.

Keywords: acute toxicity, African catfish, Dizensate glyphosate, Herbicides, necrosis

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INTRODUCTION

Most environmental problems of concern today are attributed to the production and release of toxic chemicals which are not only capable of interacting with the environment but also disrupting the ecosystem. Indiscriminate discharge of herbicides from agricultural run-off and other sources into aquatic media affects non target organisms such as fish and prawn which are of great economic importance to humans. Toxicants contaminate
freshwater bodies and affect non-target organisms. Various researchers have reported on the effects of chemicals on aquatic organisms [1].
The impact of chemical environmental contamination
on fish health, consequently fish productivity is of economical relevance for fishes as well as aquaculture. Environmental pollutants have been reported to accumulate in fish [2] and have threatened human health either directly or indirectly through the food chain. Accumulations of toxic compounds which may be carcinogenic or mutagenic were manifested as hazards [3]. However, the proper handling and use of herbicides in aquatic areas are especially critical, accidental spills or over dose can kill fish or cause other damage to its habitats that may lead to reduction in the fish population.
Environmental factors such as pH, turbidity, alkalinity, dissolved oxygen, temperature and conductivity influence the rate of reaction of the pollutants entering the water or the lethal effects on the aquatic organisms [4].
This study determines the 96h LC50 of glyphosate herbicide to adult of C. gariepinus and reports the effects on the physiology and survival of fish.

MATERIALS AND METHODS

Clarias gariepinus adults (mean wt., 215g) were acclimatized in glass tanks for 72 hours prior to the commencement of the study. The amount of herbicide which contained the require miligram of Dizensate herbicide was determined from the 480 g/L of Dizensate herbicide formulation and concentration of 9.6mg/l,
14.4mg/l, 19.2mg/l, 21.6mg/l and 24mg/l were introduced
into each of the tanks in duplicate treatments and 0.0 mg/l (control).The fish were distributed randomly in duplicate treatments into 12 glass tanks (12 fish/tank). The pH of the solutions was measured with the pH meter, temperature with mercury-in-glass thermometer and dissolved oxygen with a digital DO2/CO2 meter. The exposure lasted for
96hours. Water temperature, pH and dissolved oxygen were determined every hour for the first four hours and once every four hour for the next twenty hours and once every twenty-four hours before the end of the experiment.
The LC50 was determined graphically using logarithm
transformation at the end of the exposure period. All data obtained were subjected to Analysis of Variance (ANOVA) and multiple range test using the SAS. This investigations were conducted in accordance with the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching, published by the Consortium for Developing a Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching, First Edition, 1988; the National Research Council (NRC) publication Guide for Care and Use of Laboratory Animals (copyright 2010, National Academy of Science).

RESULTS: The concentration of Dizensate herbicide that

will bring about 50% mortality of the test organism in 96 hours is refered to as 96-h LC50. The 96-h LC50 of Dizensate herbicide to fingerlings of C. gariepinus is presented in

http://www.ijser.org

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ISSN 2229-5518

Table 1. This value (43.65mg/l) is the concentrations of the treatments required to bring about 50% mortality of C. gariepinus fingerlings within 96 hours period. The acute toxicity of Dizensate herbicide decrease with increase in time.
The fish exposed to the Dizensate herbicide solutions
showed erratic swimming, loss of reflex, peeling of the skin, discolouration, behavioural changes and increasing
opercula ventilation and movement (Table 2).
The observation is confirmed by the significantly different mortality rates obtained due to dosage, according to Aguigwo [5]. The mortality pattern recorded corroborates with that reported by Rand and Pectrocelli
[6]which stated that there should be less than 35% mortality
in one of the concentration and at least more than 65% mortality in the highest concentration. The abnormal rapid movements of the fish subjected to high concentrations of Dizensate herbicide suggest that it acted on the nerves of the fish similarly reported by Okon [7]of pesticides.
Water quality attributes are prime factors that influence fish survival, reproduction, growth performance, and overall biological production (King, [8]; king and Jonathan [9]). They affect aquatic biotic integrity by directly causing mortality and / or shifting the equilibrium among species due to subtle influences such as reduced reproductive rates or alternations in competitive ability. This inverse relationship is interesting and indicative of higher demand for oxygen prompted by condition of
hyperactivity as observed and explained by Ofojekwu et al.,
[10]and Oti [11]

Physicochemical parameter measured (Table 3) seemed to be within optimum range for fish culture as reported by Omitoyin et al. [12]and Olaifa et al. [13].There was a significant negative correlation between pH and dissolved oxygen values. There was a significant change in water quality resulting from increase in concentration of toxicant. This observation was in line with Okoli-Anunobi et al. [14]who investigated the lethal effect of the elephant

Blue detergent (R) on the Nile Tilapia Oreochronis niloticus.
In case of dissolved oxygen, the treatments did not only show a dose dependent decline in concentration, but also rapid depletion of dissolved oxygen with time. Warren [15]had earlier reported that the introduction of a toxicant
into an aquatic system might decrease the dissolved oxygen

concentration, which will impair respiration leading to asphyxiation. This was probably why the fishes were stressed progressively with time before death. Okoli- Anunobi et al. [14]also reported pH shift slightly from 6.30 to the alkaline death point of 10.75. This finding agrees with pH values in the present study.

Water qualities were also affected negatively in the exposed medium. This increase with increase in concentration of the toxicant. This will invariably affect the optimum growth and development of the cultured fish. Bacterials and other germs will thrive with bad water quality. Dissolved oxygen was noticed to decline with increase of the toxicant, a situation refers to as oxygen sag which is characterized by high mortality within short time. Death recorded could therefore have occurred by this reason.

DISCUSSION

The study was carried out to determine the toxicity of dizensate herbicide to the most cultivable fish specie in Nigeria, African catfish Clarias gariepinus. This test animal is important in capture and culture fisheries. Dizensate herbicide is toxic to Clarias gariepinus. This was revealed by the results of various investigation carried out in this study: the relatively very high values of LC50; the abnormal behavior displayed in the exposed fish as well as various degenerative changes observed in the water parameters are pointer to this. It is time that the widespread use of this
toxic chemical on ponds area, water ways, drains, streams, roadsides, footpaths, parks, gardens, schools, farms, forestry, national parks etc is stopped or highly restricted.

Table 1: Table shows the lethal concentrations (96-h

LC50) value of Dizensate herbicide to C. gariepinus

adult after several hours.

TIME (Hours) Log C value LC50

24 1.755 56.89mg/l
48 1.716 52.00mg/l
72 1.707 50.93mg/l

96 1.640 43.65mg/l Key: LC50=Lethal Concentrations

Source: Field survey, 2011

Table 2: Behavioral changes observed on Clarias gariepinus during 96h exposure to Dizensate herbicide Exposure Time 24hrs 48hrs 72hrs 96hrs CONC.(mg/l) 0,19.2,28.8,38.4,48,57.6 0,19.2,28.8,38.4,48,57.6 0,19.2,28.8,38.4,48,57.6 0,19.2,28.8,38.4,48,57.6

BEHAVIOR
Loss of reflex - - - - - - - - - - + + - - - + + + - - + + + +
Moulting - - - - - - - - - - - + - - - - + + - - - + + +

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Discolouration

- -

- +

Air gulping

- +

Erratic - - - - + + - - - + + + - + - + + + - + + + + + Swimming
Barbel - - - - - - - - - - - + - - - - - + - - + + + + Deformation
Excessive - - - - - - - - - - - - - - - - - - - + + + + + Mucus
Secretion
----------------------------------------------------------------------------------------------------------------------------------------------------------------- Key : - = Not present
+ = Present
Source: Field survey, 2011

Table 3:Physico-chemical parameters measured during the 96h exposure to Dizensate herbicide (Mean ± S.D) TIME

Befor e

1hr

2hr

3hr

4hr

8hrs

12hrs

16hrs

20hrs

24hrs

48hrs

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ascorbic acid on cadmium exposure in fish (Puntius altus). Res. J. Environ. Toxicol., 1: 27-36.
Source: Field survey, 2011

Table 4: Estimation of the Log C and the LC50 value of

Adult Catfish Clarias garienpinus exposure to dizensate for 96 hours.

[2] Akinsorotan, A. M (2005).: Effects of palm oil mill effluent on fish, water, soil sediment and submerged vegetation in river Oluwa, Okitipupa, Nigeria. MSc Thesis. Federal University of
Conc. (mg/l)
Log

Conc.
Total
No
No. Dead
% Mortality
Corrected
%
mortality
Probit
Technology Akure, 61p.
[3] Jacobs, M. N.; Covaci, A. and Schepens, P. (2002).
Investigation of selected persistent organic
T0 = 0 - 12 0 0 - -
T1 =
19.2
T2 =
28.8
T3 =
38.4
T4 =
48.0
T5 =
57.6
1.283 12 0 0 - -
1.460 12 2 17 - 4.05
1.584 12 4 33 - 4.56
1.681 12 6 50 - 5.00
1.760 12 10 83 - 5.95

Source: Field survey, 2011

96 hours LC 50 value exposed Adult to dizensate herbicide

6.0

5.5

5.0

4.5

4.0

1.45 1.50 1.55 1.60 1.65 1.70 1.75 1.80

Log 10 Concentration

pollutants in farmed Atlantic salmon (Salmo salar),
salmon aquaculture feed, and fish oil components of the feed, Environ. Sci. Technol 36:2797–2805.
[4] Fagbenro, O.A. (2002) Tilapia: Fish for thought.
Inaugural Lecture Series 32. Federal University of
Technology, Akure. 77pp.
[5] Aguigwo J.N (2002).: The toxic effect of cymbush pesticide on growth and survival of African catfish, Clarias gariepinus (BURCHELL1822). J. aquat. sci. 17 (2): 81-84.
[6] Rand, G.M., and Petrocelli, S.R., (1985), Fundamentals of aquatic toxicology Washington, Hemisphere Publishing Corporation, 666Pp.
[7] Okon, A.O. (1991) Toxic and sub-lethal effects of Piper guineense on Oreochromis niloticus. M.Sc. Thesis, University of Ibadan, Ibadan.
[8] King, R. P. (1998). Allgometry, growth
performance and mortality of Tilapia mariae Boulenger, 1899 (Cichlidae) in Ikpa River, Nigeria. Fish and Fisheries of Southeastern Nigeria,1:38 –
47.
[9] King, R. P. and Jonathan, G. E. (2003). Aquatic Environmental Perturbations and Monitoring. African Experience, USA. Pg 166.
[10] Ofojekwu, P. C.; Ayuba, V. O. and Agbon, O. A.
(2001). Acute toxicities of Basudine and Gammalin
20 to Aphyosemion gairdneri. Proc. Fisheries
Society of Nigeria (FISON), pp36- 39.
[11] Oti, E.E (2002) acute toxicity of cassava mill effluent to the African Catfish tingerlings AJOL .J.
of Aquatic Sci. Vol. 17 No

Fig.1 : Shows the LC50 for Adult of C. gariepinus at 96h exposure to Dizensate Herbicide

Source: Field survey, 2011

REFERENCES

[1] Jiraungkoorskul, W, S. Sahaphong, P. Kosai and
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[12] Omitoyin B.O, Ajani E.K, Fajimi AO (2006).
Toxicity Gramoxone (paraquat) to juvenile African catfish, Clarias gariepinus (Burchell, 1822). American Eurasian. J. Agric. Environ. Sci. 1(1): 26-
30.
[13] Olaifa, F.E, Olaifa, A.K & Lewis O.O. (2003). Toxic

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Stress of Lead on Clarias gariepinus (African catfish) Fingerlings. African Journal of Biomedical Research, 6, 101 –104.
[14] Okoli-Anunobi, C.A.I.N, Ufodike, E.B.C., & Chude
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