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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 μm s−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 μg L−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. gariepinus: % 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 differences were observed. The histological results revealed alterations 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. [ABSTRACT FROM AUTHOR]

This article discusses research that evaluated the amount of histopathological alterations in the liver of the sharptooth catfish (Clarias gariepinus) sampled from two dams in an urban nature reserve located in Gauteng, South Africa. Such research is pertinent, as biomonitoring tools in ecological toxicology assessment are needed to show the effect of pollutants on fish health in aquatic ecosystems. Water and sediment samples were taken to test for metal pollution and the existence of endocrine disrupting chemicals.

The sharptooth catfish ( Clarias gariepinus) has recently been shown to be a useful indicator species of oestrogen polluted waters in South Africa ( Barnhoorn et al., 2004 ). Knowledge of the normal reproductive biology of this species is important to be able to assess the morphological changes caused by the exposure to potentially harmful toxicants including endocrine disruptor chemicals (EDCs). Eleven sexually mature C. gariepinus males were selected from an aquarium population bred through hormone induced spawning in reconstituted reverse osmosis water. The fish were reared under controlled conditions averting exposure to potentially EDCs and allowing the description of the normal testis histomorphology of unexposed healthy specimens. The testes of C. gariepinus are paired elongated organs situated in the dorsal region of the visceral cavity. Histologically, the testes possess a lobular organization enclosed by a thin tunica albuginea. Depending on the tissue region, each seminiferous lobule contains some or all of the various developmental stages of spermatogenesis including a single primary spermatogonia, groups of secondary spermatogonia, cysts of primary and secondary spermatocytes, spermatids, and spermatozoa. Nutritive Sertoli cells are visible on the periphery of the seminiferous lobules. Interstitial tissue (including groups of Leydig cells) and blood vessels constitute most of the interlobular space. It is expected that the histological results of this study will contribute to a currently limited, but growing gonadal histological database for southern African freshwater fish species to serve as reference in future toxicity assessments. [ABSTRACT FROM AUTHOR]

Cryopreservation of antelope epididymal spermatozoa could play a vital role in future breeding by developing a successful protocol for cryo-conserving them. The aim of this study was to characterize morphology, motility rates and longevity of epididymal spermatozoa from springbok, impala and blesbok. Cauda epididymal spermatozoa were collected post-mortem from both testicles of free-ranging springbok (n=18), impala (n=21) and blesbok (n=21), and divided into two groups (pre- and post-cryopreservation). Spermatozoa were cryopreserved in Biladyl supplemented with 20% egg yolk and 7% glycerol under field conditions. Pre-freeze and post-thaw sperm quality was evaluated. The longevity of thawed spermatozoa was evaluated under culture conditions that support domestic cattle in vitro fertilization. There was a significant difference between pre-freeze and post-thaw sperm motility index (SMI) (p<0.05), plasma membrane integrity (p<0.05) and acrosome integrity (p<0.05) for all species. Post-thaw SMI and plasma membrane integrity were comparable between species (p>0.05). The effects of cryopreservation on sperm cell morphology differed between species and between specific abnormal morphology. Blesbok had the least abnormalities in post-thaw spermatozoa. Cryopreservation substantially reduced the survivability and motility rates of antelope species. Blesbok spermatozoa tolerated cryopreservation and thawing process better than impala and springbok. The antelope cauda epididymal sperm maintained viability and acrosome integrity for at least 4h following incubation under conditions that support domestic cattle in vitro fertilization (IVF) with a decline in longevity over time across species however; species responded differently over time in terms of plasma membrane integrity and acrosome integrity. The antelope species may have different in vitro culture requirements, indicating differences in sperm physiology between the species. This research could contribute species-specific protocol development for IVF thus promoting ex-situ conservation strategies of African antelope species in South Africa., (Copyright © 2011 Elsevier B.V. All rights reserved.)

This study reports on intersex in Oreochromis mossambicus, an indigenous fish species inhabiting most aquatic systems throughout South Africa (SA). Male fish were collected from three sites in the Luvuvhu River, Limpopo Province, SA: Albasini Dam (AD), Nandoni Dam (ND), and Xikundu Weir (XW). The latter two sites are situated in a currently dichloro-diphenyl-trichloroethane (DDT) sprayed area. A laboratory-bred reference group (Aq R) were included for a histological comparison. 48% of the fish at AD were intersex individuals compared with 63% at ND, and 58% at XW. The Aq R fish had no cases of intersex. o,p'- and p,p'-DDT and metabolites dichlorodiphenyldichloroethane (DDD) and -dichlorodiphenyldichloroethylene (DDE) were detected in fat samples, indicative of contamination of the aquatic environment and subsequent exposure of fish to these chemicals. Although some of the fat samples contained levels of DDTs no association could be established between intersex and chemical contaminants in fish., (Copyright © 2010 Elsevier Inc. All rights reserved.)

This is the first histological evidence of intersex in a fish species inhabiting a South African water source. One hundred catfish (Clarias gariepinus) were collected randomly from the Marais Dam (MD) and the Rietvlei Dam (RVD) in the Rietvlei Nature Reserve (RNR), South Africa. These dams drain water from a stream that receives effluent from industrial sites, agricultural activities, informal settlements, and municipal treatment plants. Each fish was evaluated macroscopically and had blood drawn, and its gonads were macroscopically and histologically examined to verify intersex potentially related to endocrine disruption. Gonadal histology of several fish showed primary oocytes scattered in testicular tissue, indicative of intersex. The results showed intersexuality in 20% of fish from both the dams. The GSI value for intersex fish was closer to male GSI values, suggesting that the sampled intersex fish were more likely to have occurred from the feminization of male catfish. Target chemical analyses showed that the water, sediment, and serum samples tested positive for p-nonylphenol (p-NP). The p-NP level in water and sediment at MD was 6360 and 4.0 microg/kg, respectively, whereas in sediment at RVD it was 113 microg/kg. Commonly found in the effluent from sewage treatment plants, p-NP in water and sediment indicates estrogenic water pollution, which might affect wildlife and humans dependent on these sources., (Copyright 2004 Wiley Periodicals, Inc.)