Behavioral and biochemical responses of hybrid striped bass during and after fluoxetine exposure

Environmental contaminants, including pharmaceuticals, can alter behavior and possibly impact population and community structures. One important behavior that could be impacted is the ability to capture prey. We hypothesized that sublethal fluoxetine exposure may lead to feeding behavior abnormalities in hybrid striped bass (Morone saxatilis × M. chrysops). Fluoxetine is an antidepressant that acts as a selective serotonin reuptake inhibitor (SSRI). A change in serotonin levels affects multiple behaviors including feeding, which is an important aspect in ecological fitness. This research characterized the impact of sublethal fluoxetine exposures on the ability of hybrid striped bass to capture fathead minnows (Pimephales promelas). Bass were exposed to fluoxetine (0.0 μg/l, 23.2 ± 6.6, 51.4 ± 10.9 and 100.9 ± 18.6 μg/l,) for 6 days, followed by a 6-day recovery period in clean water. Brain serotonin activity and the ability of bass to capture prey were measured every third day. Exposed fish exhibited a concentration- and duration-dependent decrease in ability to capture prey. Increased time to capture prey also correlated with decreases in brain serotonin activity. Serotonin activity also decreased in an exposure time- and concentration-dependent manner, maximally inhibited 23.7, 28.0, and 49.1% of control in the low, medium, and high treatments, respectively. Serotonin levels in exposed fish did not recover to control levels during the 6-day recovery period. These results suggest that sublethal exposure to fluoxetine decreases the ability of hybrid striped bass to capture prey and that serotonin can be used as a biomarker of exposure and effect.