The effect of 4-nonylphenol on semen quality, viability of gametes, fertilization success, and embryo and larvae survival in rainbow trout (Oncorhynchus mykiss)

The present study investigated in vivo and in vitro effects of environmental relevant concentrations of 4-nonylphenol (100-750 ng l(-1)) on the reproduction of rainbow trout (Oncorhynchus mykiss). To determine the effect of 4-nonylphenol on semen quality rainbow trout were exposed to three concentrations of 4-nonylphenol in a flow-through system during the spawning period (60 days). At an estimated 4-nonylphenol concentration of 750 ng l(-1) semen production was completely inhibited, at 280 and 130 ng l(-1) the semen production was significantly reduced in comparison to the control. Sperm density, sperm motility and sperm fertility were not affected. Also the development of embryos and larvae at the end of yolk sac stage was affected by 4-nonylphenol. At estimated 4-nonylphenol exposure levels of 280 and 750 ng l(-1) the percentage of eyed stage embryos was slightly but significantly lower (2-4%) than at 130 ng l(-1) 4-nonylphenol and in the control. At 4-nonylphenol concentrations of 750 ng l(-1) only 23.8 +/- 1.2% of the larvae survived to the end of the yolk sac stage, at 280 ng l(-1) 53.7 +/- 8.2%, at 130 ng l(-1) 73.8 +/- 1.5%, and in the control 70.9 +/- 1.8%. Sperm motility was not affected by 4-nonylphenol as sperm motility rate, swimming velocity, swimming pattern and motility duration were similar in water and in water containing of 100, 250, or 750 ng l(-1) 4-nonylphenol. Incubation of eggs in physiological saline solution containing of 100, 250, or 750 ng l(-1) 4-nonylphenol did not change their fertilizability in comparison to the control. Therefore, 4-nonylphenol did not affect the egg viability. Also the fertilization process (sperm egg contact) was not influenced by 4-nonylphenol as the fertilization rate (percentage of hatched larvae) was similar to the control when eggs were fertilized in water containing of 100, 250, or 750 ng l(-1) 4-nonylphenol.