TOXICITY OF ATRAZINE (HERBICIDE) TO JUVENILES OF THE AFRICAN CATFISH, CLARIAS GARIEPINUS (BÜRCHELL, 1822)
TOXICITY OF ATRAZINE (HERBICIDE) TO JUVENILES OF THE AFRICAN CATFISH, CLARIAS GARIEPINUS (BÜRCHELL, 1822)
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Date
2017-02
Authors
BAYERO, Umar
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Abstract
In the present study, juveniles of Clarias gariepinus were exposed to the herbicide
atrazine in order to determine the herbicide‟s toxicity to the species at both acute and
sub-lethal exposures.Fish were exposed to acute concentrations of 9, 10, 11, 12 and
13mg/L of atrazine, as well as sub-lethal doses of 0.59, 1.19 and 2.38mg/L of atrazine.
Both experiments had a control that served as a reference point. Effects of the herbicide
were measured using behavioural, haematological, biochemical, histopathological as
well as growth indices (as suggested by previous authors). Results of the acute toxicity
test showed that atrazine was toxic to the species in a dose-dependent manner. The LC50
value of atrazine established for the species was 11.89mg/L. Most importantly, atrazine
induced hyperactivity at acute levels of exposure. Significant (p<0.05) haematological
changes observed at both acute and sub-lethal exposures included anaemia,
leukocytosis, proteinaemia, haemoglobinaemia, neutrophilia as well as lymphocytosis.
Acute and sub-lethal concentrations of atrazine also induced an increase in the
generation of reactive oxygen species. Histopathological changes observed in the gills
included attenuation and clubbing at the tips of the primary lamellae, gradual
degeneration of the primary lamellae, total dislocation of the primary lamellae from its
position as well as mild congestion in the cartilage. Changes in the liver of exposed fish
included perivascular cuffing around the central vein, mild congestion of the sinusoids, pyknosis of the nuclei, mild necrotic damage, congestion of the central vein as well as
mild coagulative necrosis. Atrazine also had effect on the growth parameters (weight
gain, percentage live weight gain and specific growth rate) as well as nutrient utilization
parameters (feed conversion efficicency, feeed conversion ratio, gross feed conversion
efficiency and nitrogen metabolism) although some of these effects were not
statistically significant (p>0.05). The study revealed that atrazine was moderately toxic to C. gariepinus juveniles and affected the behaviour, haematology, biochemistry,
histology as well as growth of the fish. Hence, use of the herbicide should be with
caution especially near water bodies.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE
STUDIES, AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD
OF MASTER DEGREE IN BIOLOGY
DEPARTMENT OF BIOLOGY
FACULTY OF LIFE SCIENCES
AHMADU BELLO UNIVERSITY,
ZARIA, NIGERIA
Keywords
TOXICITY,, ATRAZINE (HERBICIDE),, JUVENILES,, AFRICAN CATFISH,, , CLARIAS GARIEPINUS,, (BÜRCHELL, 1822)