Ecotoxicology Biomarker of liver function using Clarias gariepinus
Clarias gariepinus, which is indigenous from Africa (Rahman et al. 1992), is one of the most important tropical catfish species for aquaculture (de Graaf and Janssen 1996) in spite of its commanding presence in the wild. This might have been due to its high growth rate, omnivorous feeding habit, high feed conversion rates and hardiness, including its high resistance to handling and stress (Olaifa et al. 2003; Eyo and Ezechie 2004; Akinsanya and Otubanjo 2006; Ogundiran et al. 2009). Clarias gariepinus is known to tolerate harsh aquatic conditions (Hogendoorn 1992; Bruton 1979) in terms of low dissolved oxygen concentrations by utilizing both dissolved and atmospheric oxygen (Okechi 2004), especially in fishes above 12 – 14 days old with functionally developed accessory respiratory organs (Peteri et al. 1992). Though C. gariepinus can endure long periods of draughts (Dunn 2000), it cannot survive long in water temperature below 9 – 10ºC (Peteri et al. 1992). These endearing qualities may have increased the importance of C. gariepinus in ecotoxicological studies (Weckler 2000).
Clarias gariepinus, like any other aquatic organism, live in direct contact with the aquatic environment where some changes are rapidly reflected as measurable patho-physiological alterations in exposed fishes (Wilson and Taylor 1993; Musa and Omoriegie 1999; Seith and Saxena 2003). However, such measurable changes depend upon the biological status of exposed fish as well as upon the type and duration of their exposure to toxicants within that aquatic environment (Brungs 1977). That is why fishes are used as acceptable bio-indicators of environmental pollution (Nussey et al. 1995; Kock et al. 1996; Borkovic et al. 2008; Kim et al. 2008), especially as most aquatic waters are constantly being threatened by the environmental pollution (Biney, et al. 1987; Svensson et al. 1996; Adamu and Kori-Siakpere 2008). This is because normal physiological processes are long affected before the death of an organism thereby creating the need for physiological and biochemical indicators of health and sub-lethal effects of the toxicants (Van Vuren 1986; Van der Merve et al. 1993).
The increasing spates of water pollution have continued to be a major problem in Nigeria and other developing countries (Adelegan 2008). Ayodele and Abubakar (2001) and Sani (2011) have reported the pollution of Tiga dam, Nigeria. However, there is dearth of information on the effects of such pollution on the haematological and biochemical profile of Tiga dam’s fish biota. Thus, this study aimed to evaluate the haematology and biochemistry of C. gariepinus as biomarkers of environmental pollution in Tiga dam, Nigeria.