International Journal of Aquaculture, 2017, Vol.7, No.9, 64-70
64
Research Report
Open Access
Acute Toxicity and Haematology of
Clarias gariepinus
Exposed to Selenium
D.O. Odedeyi, K.E. Odo
Department of Animal and Environmental Biology, Faculty of Science, Adekunle Ajasin University, Akungba-Akoko, Ondo State, Nigeria
Corresponding author Email:
International Journal of Aquaculture, 2017, Vol. 7, No.9 doi:
Received: 22 May, 2017
Accepted: 15 Jun., 2017
Published: 30 Jun., 2017
Copyright © 2017
Odedeyi and Odo, 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
:
Odedeyi D.O., and Odo K.E., 2017, Acute toxicity and haematology of
Clarias gariepinus
exposed to selenium, International Journal of Aquaculture, 7(9):
64-70 (doi:
Abstract
The acute toxicity and haematological effect of selenium was investigated on
Clarias gariepinus
juvenile. 180 healthy
C.
gariepinus
juveniles with mean weight of 7.4 ± 0.64 g and length of 11.2 ± 0.88 cm were exposed to different concentrations (0, 2, 3,
4, 5 and 6 mg/l) of selenium under a static method of bioassay for 96 hours. The mortality rate of the experimental fish increased
with increase in concentration of the selenium. The 24, 48, 72 and 96 hours LC
50
were estimated to be 8.49, 6.36, 4.80 and 3.39 mg/l
respectively which was analysed using probit method. The dissolved oxygen of the culture media was significantly lower p < 0.05 in
the treatments when compared to the control. The blood parameters: Pack Cell Volume (PCV), Red Blood Cell (RBC), White Blood
Cell (WBC) and Haemoglobin (Hb) showed decrease from lowest concentration (2 mg/l) to highest concentration (6 mg/l). There
were variations in the derived haematological indices of mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH)
and mean corpuscular haemoglobin concentration (MCHC). In conclusion, it was observed that selenium at high concentration is
toxic and caused a successive population decline of
C. gariepinus
. Fish farmers should as much as possible locate farms from likely
source of toxicants.
Keywords
Selenium;
Clarias gariepinus
; LC
50
; Haematology
1 Introduction
Water pollution has become a global problem and rapid industrialization is one of the main causes of aquatic
pollution because most of their effluents are being discharged in the aquatic environment. Heavy metal pollution
is one of the most important environmental problems today. Contamination of fresh water with a wide range of
pollutants has become a matter of concern over last few decades (Vutukuru, 2005). Modern industries are to a
large extent, responsible for contamination of the environment. Nriagu and Pacyna (1988) reported that industrial
wastes contain various types of toxic metals. These include: Hg (mercury), Cr (chromium), Pb (lead) Se
(selenium), Zn (zinc), Cu (copper), Ni (nickel), Cd (cadmium), As (arsenic), Sn (tin), etc. Heavy metals are high
priority pollutants because of their relative high toxicity and persistent. Though, many metals play a vital role in
the physiological processes of plants, animals and humans, yet excess concentration of metals is harmful (Ololade
and Oginni, 2010). The effect of heavy metals on aquatic organisms is currently attracting widespread attention,
particularly in studies related to pollution (Khalid, 2011). Selenium is an essential trace element which is required
in animal diet, including fish for normal growth and physiological function of animal (Abbas, 2009) it is also
required for maintenance of homeostatic functions at trace concentrations (Monterio et al., 2009a). However,
selenium can bio accumulates and become toxic. It is used in a number of industrial and manufacturing processes
including photoelectric cells, steel manufacture, anti-dandruff shampoos, fungicide, and glass manufacturing
(Nagpal, 2001). Selenides (-2) are usually present as organic compounds (Bowie et al., 1996), such as
selenomethionine and selenocysteine (Combs and Combs, 1986), and are physically and chemically similar to
sulphides (Banks, 1997). Major anthropogenic sources of Se include fossil fuel combustion, mining, and
agricultural drainwater (Haygarth 1994; Lemly, 1999). Other anthropogenic sources that may increase selenium
contamination are open pit phosphate mining, wetlands constructed to treat Se-laden wastewater, and feedlot
waste (Lemly, 1999). Upon entering an aquatic ecosystem, Selenium may be absorbed or ingested by aquatic
organisms, bind to particulate matter, or stay free in solution (Lemly and Smith, 1987). African catfish (
Clarias
