| dc.description.abstract | Pharmaceutical compounds persist in the aquatic environment on a global scale. Investigating the potential environmental risks that these chemicals pose, despite being detected at low concentrations, is therefore paramount. This is especially true when multiple contaminants are combined. Previous studies have reported that diclofenac and ciprofloxacin may cause adverse effects on the reproductive health of invertebrates, such as the blue mussel (Mytilus edulis). However, laboratory exposure concentrations were higher than those detected in the aquatic environment.
The present study aimed to investigate the effect of environmentally relevant concentrations (500, 1000 and 10000 ng/L) of diclofenac, ciprofloxacin and a binary mixture (500 ng/L of each pharmaceutical) on the fertilizing potential by determining the effect on spermatozoa function of the blue mussel. To determine the effect on fertilizing potential of mussel sperms, both in vivo and in vitro approaches were utilized. Specifically, male gametes were investigated after a 60 min in vitro exposure to the selected pharmaceuticals for presence of reactive oxygen species (ROS), intact mitochondrial membrane potential (MMP) and viability. These functional parameters were chosen as their impairment help predict a decrease in reproduction and consequently an impact at population and ecosystem level.
For the chronic in vivo experiment, adult mussels were exposed for six weeks, male individuals were dissected before the sperms were extracted and pooled in groups according to the treatments for the same functional testing as the acute in vitro exposure.
In all experiments at least one environmentally relevant concentration showed a significant difference compared to the control, indicating that the selected pharmaceuticals can have a negative impact on marine ecosystems by decreasing the fertility potential of M. edulis. The mechanism behind this toxicity is not well understood at the time of writing this thesis. Therefore, further research is foreseen as necessary to investigate this aspect. | |