Haematological and Histological Changes in Tilapia (Oreochromis Mossambicus) Exposed to Cadmium and Chlorpyrifos
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Date
2015-05-10
Authors
Journal Title
Journal ISSN
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Publisher
Karnataka Veterinary, Animal and Fisheries Sciences University, Bidar
Abstract
The pollution of aquatic ecosystems with chemical contaminants has become one of
the most critical environmental problem of the century. Heavy metals, pesticides and many
other organic chemicals, are the harmful group of pollutants in aquatic habitat, almost
crossed the level of acceptable limit, causing acute and chronic toxicity to fish fauna. One of
the early symptoms of acute heavy metal and pesticide poisoning is the alteration in the
haematological profile and morphological changes in different organs like gill, liver and
kidney.
A bioassay was conducted to determine the lethal toxicity (LC50) of heavy metal,
Cadmium and commercial grade Organophosphate insecticide, Chlorpyrifos (20% EC) on
Tilapia (Oreochromis mossambicus). The lethal toxicity (LC50) of Cadmium, Chlorpyrifos,
Cadmium + Chlorpyrifos and Chlorpyrifos + Cadmium were found to be 169.80ppm,
0.022ppm, 92.04ppm and 0.016ppm, respectively. The lethal toxicity result reveaed that,
Cadmium and Chlorpyrifos are more toxic to fish in combinations compared to their
individual exposures. For sublethal toxicity study, the fishes were exposed to two sublethal
concentrations (i.e 1/5th of LC50
and 1/10th of LC50) for up to 21days.
In the present study, significant decrease in RBC count, haemoglobin content and
haematocrit value, erythrocyte indices and increase in WBC count with severe morphological
changes in the gills, liver and kidney were observed in fishes treated with two sublethal
concentrations of Cadmium, Chlorpyrifos and mixture of Cadmium and Chlorpyrifos.
It was concluded that mixture of Cadmium + Chlorpyrifos cause severe alterations in
haematological parameters compared to its individual exposure. The nature of damage
caused by pesticide and heavy metal was different in different organs of the fish. At sublethal
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levels, the Chlorpyrifos caused more damage to the gills while liver was most affected in the
presence of Cadmium. On the other hand, a combination of Cadmium + Chlorpyrifos caused
more damage to the kidney.
Description
Ph.D. Thesis
Keywords
Cadmium, Chlorpyrifos, Lethal toxicity, Oreochromis mossambicus, Haematology and Histology