Preliminary results on sperm motility and testicular histology of two feral fish species, Oreochromis mossambicus and Clarias gariepinus, from a currently DDT-sprayed area, South Africa By M. J. Marchand 1 , G. M. Pieterse 1 and I. E. J. Barnhoorn 2 1 Department of Zoology, University of Johannesburg, Johannesburg, South Africa; 2 Andrology, Department of Urology, University of Pretoria, Pretoria, South Africa Summary The effects of DDT and its metabolites on the reproductive health of two fish species (Clarias gariepinus and Oreochromis mossambicus) were studied using the gonadosomatic index (GSI), gonadal histology and computer assisted sperm analysis (CASA). DDT and its metabolites, DDE and DDD are endocrine disrupting chemicals posing estrogenic and anti- androgenic properties, which have detrimental effects on growth and reproduction. Although DDT was banned internationally, it is still used for Malaria vector control in areas of South Africa. Both species were sampled at a reference site, Albasini dam (AD), (outside the DDT-sprayed area, <0.01 lgL )1 of DDT) and at an exposed site, Xikundu weir (XW), in the same river ± 70 km within the DDT-sprayed area, <0.01 lgL )1 of DDT. Gill nets were used to acquire a sample size of 10 male fish per site for each species. Both testes were dissected out and the GSI calculated. Uncontaminated milt was collected and ana- lyzed using a novel CASA system based on open source software for characterization of sperm motility parameters. Testis tissue sampled for histology was fixed in Bouins and processed according to standard methods. The sample size obtained at the reference site (AD) was O. mossambicus n = 6, C. gariepinus n = 9; and at the exposed site (XW) was O. mossambicus n = 10, C. gariepinus n = 3. The GSI results showed a lower value for O. mossambicus at XW (0.06) (n = 13) than AD (0.12) (n = 6); U = 16.0, P = 0.044. However the opposite was true for C. gariepinus. Exposure to various environmental toxicants can result in gonadal changes such as decreased GSI, morpho- logical alterations or both. Histological assessment showed histopathological alterations to testes tissue including intersex (only in O. mossambicus) and detachment of basal membranes. The CASA results showed a decrease in parameters from the reference site (AD) to the exposed site (XW) for both species. The decrease in percent motility (% MOT) for O. mossambicus from the reference site (AD) (n = 6) to the exposed site (XW) (n = 13) was statistically significant; U = 13.0, P = 0.023. C. gariepinus from the exposed site (XW) was most affected in terms of percent motility (10.00%) and velocity (67.94 lms )1 ). Detailed assessment of the environmental effects of DDT in this area seems crucial before population impacts become evident. Introduction Pollutants contaminating aquatic ecosystems may affect the health of fish either indirectly through their diet or directly by uptake from the water. Fish populations and health are a growing concern as they provide an increasingly important source of protein for humans and are part of the natural diet of both aquatic mammals and birds (Kime et al., 1996). It has been suggested that the cause of declining male reproductive health is related to synthetic substances that bioaccumulate and act as hormonally active substances, such as organochl- orines (Skakkebaek and Keiding, 1994; Dalvie et al., 2004a). It is not surprising that even chemicals with a low affinity for a hormone receptor can still manage to compete with endo- genous hormones for binding sites, given the increased levels of chemicals present in certain aquatic ecosystems and the relatively low levels of circulating hormones within a living organism (Alavi et al., 2008). It is often not clear if this is due to interference with the pituitary–hypothalamic system or to direct action on the testes themselves. Direct effects are either cytotoxicological, where damage occurs to the cellular func- tion of gonadal cells, or endocrine where endocrine malfunc- tion disrupts the function of specific cells (Kime, 2001). Any alterations in either the timing of endocrine signals or in blocking their functions can result in alterations to the development of growth, reproduction, nervous and immune functions (Alavi et al., 2008). Similar effects have been found in laboratory animals, fish and wildlife (Colborn et al., 1993; Gray, 1998; Barnhoorn et al., 2004; Rogan and Chen, 2005). The organochlorine DDT [1,1,1-trichloro-2,2-bis(p-chlorophe- nyl)ethane], first synthesized in 1874, became widely used for its insecticidal properties (Rogan and Chen, 2005). Although DDT was banned internationally in 2001, it remains in use as a cost-effective method for malaria vector control in many countries, including areas of South Africa, in accordance with the Stockholm convention which came into force on 17 May 2004. It is still a major concern for South Africa and although alternatives have been used, DDT was reintroduced as resistance to the alternative (pyrethroid insecticides) from mosquito vectors lead to an epidemic, which has only recently declined (Bouwman, 2004). DDT and its metabolites, dichlordiphenyldichloroethylene (DDE) and 1,1-dichloro-2,2-bis(R-chlorophenyl)ethane (DDD) are known endocrine disrupting chemicals posing estrogenic and anti-androgenic properties (Kavlock et al., 1996; Sonnenschein and Soto, 1998). They have detrimental effects on growth and reproduction (Fry and Toone, 1981; Peakall and Fox, 1987; Mac and Edsall, 1991; Leatherland, 1993; White and Hoffman, 1995; Kavlock et al., 1996; Alavi et al., 2008), cause deformation of the seminiferous lobules, degeneration of the germinal cells, primary and secondary J. Appl. Ichthyol. 24 (2008), 423–429 Ó 2008 University of Johannesburg Journal compilation Ó 2008 Blackwell Verlag, Berlin ISSN 0175–8659 Received: September 15, 2007 Accepted: April 18, 2008 doi: 10.1111/j.1439-0426.2008.01141.x U.S. Copyright Clearance Centre Code Statement: 0175–8659/2008/2404–0423$15.00/0 www.blackwell-synergy.com