Sperm motility and testicular histology as reproductive indicators of fish health of two feral fish species 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; 2 Andrology, Department of Urology, University of Pretoria, Pretoria, South Africa Summary Sperm motility and testicular histology were studied as reproductive indicators of the reproductive capacity for two wild, indigenous fish species (Oreochromis mossambicus and Clarias gariepinus) from a currently DDT sprayed area in South Africa. An important component of fish health is an optimally functioning reproductive system. Computer assisted sperm analysis (CASA), based on open-source software, was used to assess sperm motility parameters including percent motile sperm (% MOT), velocity curvilinear (VCL lms )1 ) and progression (PROG). Both species were sampled at a reference site, Albasini dam (AD), and at two exposed sites, Nandoni Dam (ND) and Xikundu weir (XW). DDT and its metabolites were found in varying concentrations in the water from all three sites (0.1–1.2 lgL )1) . The CASA results showed a general trend of a decrease in all parameters from the reference site (AD) to the exposed sites (ND and XW) for both species [O. mossambicus: % MOT: 69.89 (AD), 65.92 (ND), 56.62 (XW); VCL: 89.24 (AD), 117.05 (ND), 82.49 (XW); PROG: 2922.06 (AD), 2734.14 (ND), 2431.52 (XW); C. gar- iepinus: % MOT: 39.90 (AD), 20.25 (ND), 39.10 XW); VCL: 99.93 (AD), 80.72 (ND), 88.61 (XW); PROG: 2502.72 (AD), 2340.89 (ND), 1915.73 (XW)], however few significant differ- ences were observed. The histological results revealed altera- tions to testis tissue of both species at all three sites. The testes were assessed through the identification of alterations and an organ index was calculated: Testes Index (I T ). The index is indicative of the histological response in the respective tissue type. O. mossambicus at XW had the highest mean I T value (5.47 ± 4.63), primarily due to the occurrence of testicular oocytes (intersex). There is a vital need for a dependable method or indicator to assess reproduction of fish in situ in order to relate impacts of environmental EDCs with changes in reproductive success of indigenous fish populations. Introduction The principal goal of environmental conservation and man- agement is to prevent unfavourable biological and ecological effects caused by pollution and anthropogenic influences to organisms and the ecosystems which they inhabit. Therefore, a need has arisen for sensitive bio-monitoring tools as indicators of the effect of pollution on aspects such as fish health in aquatic ecosystems. An important component of fish health, and more importantly population stability, is an optimally functioning reproductive system. For successful fertilization in fish, it is essential for the male to produce motile and viable sperm that can locate the eggs and then the micropyle for entry into the oocyte (Kime, 2001). The reproductive system is controlled and regulated by the endocrine system (Damstra et al., 2004), known to be affected by endocrine disrupting chemical (EDCs). EDCs have been defined as exogenous substances that alter function(s) of the endocrine system and consequently cause adverse health effects in an intact organ- ism, or its progeny, or (sub)populations (EPA, 1997). The reproductive system is programmed during fetal devel- opment and an abnormal environment (exposure to EDCs) during this critical stage can result in permanent misprogram- ming (Damstra et al., 2004). The hypothalamus-pituitary- gonadal axis (HPG), part of the endocrine system, has developed in vertebrates as the hormonal governor over spermatogenesis, oogenesis and reproduction in general (Bray et al., 1999). This axis is comprised of three components; gonadotropin releasing hormone (GnRH) neurons, from the hypothalamus; secretion of gonadotropins, luteinizing hor- mone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary; and the somatic cells of the testes and ovaries (Damstra et al., 2004). In the male, hypothalamic and pituitary control of LH and FSH secretion is controlled by feedback from the testis. Both the Leydig and Sertoli cells are involved in steroidogenesis within the teleost testis (Grier, 1981). Teleosts have at least two pituitary gonadotropins that are structurally and functionally homologous to FSH and LH (Cheshenko et al., 2008). The steroidal hormone estrogen is involved in the control of reproductory processes, including sexual differentiation, maturation, control of the cell cycle and proliferation (Chang et al., 2005). Estrogens have commonly been associated with the regulation of female functions, however, they are produced in male vertebrates (Schultz and Miura, 2002) and estrogen receptor (ER) activity is expressed throughout the HPG axis (Grier, 1981) and in the testes of a variety of vertebrate species. This observation led to the suggestion that estrogens take part in the regulation of testicular function (Wu et al., 2001; Damstra et al., 2004). Taking this into account, reproduction is viewed as one of the main components of fish health, as problems with the reproductive system may indicate problems with the endocrine system. EDCs, such as 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites, 1,1-dihloro-2,2-bis(p-chlorophe- nyl)ethylene (DDE) and 1,1-dihloro-2,2-bis(p-chlorophe- nyl)ethane (DDD), are known to affect the morphology and motility of fish sperm in a number of ways. According to Kime (2001), the hormonal regulation of spermatogenesis or func- tion of the Sertoli cells may be disturbed, the seminal fluid or J. Appl. Ichthyol. 26 (2010), 707–714 Ó 2010 Blackwell Verlag, Berlin ISSN 0175–8659 Received: March 14, 2010 Accepted: August 1, 2010 doi: 10.1111/j.1439-0426.2010.01558.x U.S. Copyright Clearance Centre Code Statement: 0175–8659/2010/2605–0707$15.00/0 Applied Ichthyology Journal of