Sperm motility, fertilization, and larval development of silver catfish (Rhamdia quelen) in copper-contaminated water

Abstract

The objective of this study was to evaluate the effect of copper-contaminated water on sperm motility, fertilization, and embryonic and larval development of silver catfish (Rhamdia quelen). A randomized experimental design with five treatments and four replicates was used. Two experiments were carried out: (1) controlled fertilization was performed under different levels of copper contamination and egg hatching was performed in clean water; and (2) copper-contaminated water was used for both fertilization and hatching assays. The time of sperm motility and sperm motility rates linearly decreased with increasing copper concentration in the water. Fertilization and hatching rates were also affected when the concentrations of copper in the water were above 0.0979 mg Cu +2 L -1 and 0.0331 mg Cu +2 L -1 , respectively. Gamete exposure to levels between 15 mg Cu +2 L -1 and 60 mg Cu +2 L -1 for short periods of time negatively affected sperm motility, oocyte fertilization, and egg hatching rates. In addition, when gametes and embryos were exposed at levels above 0.03 mg Cu +2 L -1 during long periods of time, egg hatching rates were reduced, and at levels between 0.05 mg Cu +2 L -1 and 0.20 mg Cu +2 L -1 the number of abnormal larvae increased. Key words: Embryo. Fish. Heavy metal. Reproduction. Spermatozoa. ResumoO objetivo deste estudo foi avaliar o efeito da água contaminada de cobre na motilidade espermática, fertilização e desenvolvimento embrionário e larval de jundiá (Rhamdia quelen). O delineamento experimental foi inteiramente casualizado, com cinco tratamentos e quatro repetições. Dois ensaios foram conduzidos: (1) a fertilização controlada foi realizada com diferentes níveis de água contaminada com cobre e a incubação do ovo realizada em água limpa; e (2) a contaminação da água foi utilizada tanto na fertilização e quanto na incubação dos ovos. O tempo de motilidade de espermatozóides e as taxas de motilidade do esperma foram reduzidas com o aumento da concentração de cobre na água. As taxas de fertilização e eclosão também foram afetados quando as concentrações de cobre na água