International Journal of Marine Science, 2017, Vol.7, No.29, 284-291
284
Research Article Open Access
Responses and Histopathological Studies of
Clarias gariepinus
Exposed to
Selenium Toxicity
Kehinde Esther Odo
, Dominic Olabode Odedeyi
Department of Animal and Environmental Biology, Faculty of Science, Adekunle Ajasin University, Akungba-Akoko, Ondo State, Nigeria
Corresponding email
International Journal of Marine Science, 2017, Vol.7, No. 29 doi
Received: 04 Jul., 2017
Accepted: 01 Aug., 2017
Published: 03 Aug., 2017
Copyright © 2017
Odo and Odedeyi, This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Odo K.E., and Odedeyi D.O., 2017, Responses and histopathological studies of
Clarias gariepinus
exposed to selenium toxicity, International Journal of Marine
Science, 7(29): 284-291 (doi
Abstract
Various toxicants have been deposited into aquatic environment due to human activities, in light with this, 180 healthy
Clarias gariepinus
juveniles with mean weight of 7.4±0.64 g and length of 11.2±0.88 cm were exposed to different concentrations of
selenium (a typical toxicant) to evaluate its behaviour and histopathological response. The fish were exposed to different
concentrations (2, 3, 4, 5 and 6 mg/L) of selenium under a static bioassay for 96 hours after a range finding test and 96 hours LC
50
was determined using probit method. 10 fish per concentration was used for the bioassay in triplicates. The 96 hours lethal
concentration (LC
50
) was estimated to be 3.39 mg/L. The histological examination of the gill revealed hyperplasia and haemorrhage
of the gill lamellar. The kidney showed vacuolation and blood stains while the skin demonstrated mucosal eruption. These alterations
increase with increase in selenium concentration. Selenium at high concentration has shown to induce behavioural changes on fish
and also alterations to organs of C
gariepinus
juvenile. It is therefore recommended that industries ensure the incorporation of
effluents treatment plants to treat wastes before discharging into the environment.
Keywords
Selenium toxicity; Histopathology; Behavioural changes;
Clarias gariepinus
Introduction
Human activities have been identified as the major cause of aquatic pollutant over decades and industries
discharge their effluents indiscriminately into water body without proper treatment (Mehjbeen and Nazura, 2013).
Heavy metals have been found to be the major chemicals present in these industrial effluents which are harmful to
aquatic life. Freshwater are highly vulnerable to pollutants since they act as immediate sink for the consequences
of human activity and always associated with danger of accidental discharges or criminal negligence (Vutukuru,
2003). Fish mostly have the tendency to bioaccumulate heavy metals and human might be at great risk some time
even lethal, through contamination of food chain (Ui, 1972). Heavy metals have devastating effects on ecological
balance of the recipient environment and a diversity of aquatic organisms. Selenium is a metalloid that is
commonly used in industrial and manufacturing processes like photoelectric cells, steel manufacture,
anti-dandruff shampoos, fungicide, and glass manufacturing (Nagpal, 2001). Major anthropogenic sources of
selenium include fossil fuel combustion, mining, and agricultural drain water (Haygarth, 1994; Lemly, 1999).
Sources that may increase selenium contamination are open pit phosphate mining, wetlands constructed to treat
Se-laden wastewater, and feedlot waste (Lemly, 1999). When selenium entered aquatic ecosystem, it may be
absorbed or ingested by aquatic organisms, bind to particulate matter, or stay free in solution (Lemly and Smith,
1988). Selenium accumulates primarily in the gonad and muscle tissue (Kennedy et al., 2000). Thus, even small
inputs of selenium into a water body may quickly accumulate up the food chain poisoning higher trophic levels
(Farombi et al., 2007). Behavioural measurement has been used as indicator of toxic stress in fish. Fishes in a
contaminated environment show some altered behavioural patterns which may include avoidance, locomotive
activity and aggression and these may cause fish attempt to escape or adjust to the stress condition (Morgan et al.,
1991; Gormley and Teather, 2003). Behavioural functions are generally quite vulnerable to contaminant
exposures, and fish often exhibit these responses first when exposed to pollutants (Little et al., 1993; Ololade and
Oginni, 2010). Histological biomarkers of toxicity in fish organ are a useful indicator of environmental pollutant
(Peebua et al., 2008). Several histological changes have been reported in the gills, liver, kidney and gonads of fish
