Trace elements content in semen and their interactions with sperm quality and RedOx status in freshwater fish Cyprinus carpio: A correlation study

Objective of the present study was to investigate interactions between trace elements content and RedOx status, as well as sperm quality parameters (motility features, DNA fragmentation) in fish spermatozoa in natural conditions. Reproductively mature male freshwater fish (n = 16) of Cyprinus carpio breed were used in the study. Trace elements content was determined in fish milt samples by inductively-coupled plasma optical emission spectrometry (ICP-OES) and by cold-vapor atomic absorption spectroscopy (CV-AAS). Sperm quality evaluation was realized by computer-assisted sperm analysis (CASA) quantifying several parameters: concentration, total motility, progressive motility, distance average path, distance curved line, distance straight line, velocity average path, velocity curved line, velocity straight line, straightness, linearity, amplitude of lateral head displacement and beat cross frequency. The general scheme of descending concentrations of trace metals in semen samples was following: Zn > Fe > Cu > As > Sr > Ni > Mn > Se > Pb > Cr > Cd > Hg. Total motility of spermatozoa was relatively high (91.45%), however progressive motility was not even half of this value (39.47%). Sperm DNA fragmentation values were relatively low (4.00-6.29%). The percentage of immotile spermatozoa showed a significant correlation with all RedOx status parameters and also with DNA fragmentation. Positive statistically significant correlations were observed between trace elements (Mn, Se, Sr, and Zn) and some qualitative spermatozoa parameters (velocity and distance parameters). Cu and Hg content shows similar negative associations with progressive motility. Hg also interacted with production of malondialdehyde. Overall, the present study suggests application of multi-component mixtures of environmentally related trace elements concentrations when assessing the potential reproductive risk.