Long-Term Pharmaceutical Contamination and Temperature Stress Disrupt Fish Behavior

Area of Science:

• Environmental toxicology
• Ecotoxicology
• Animal behavior

Background:

• Anthropogenic stressors, including pharmaceutical pollution, significantly impact natural environments.
• Understanding the combined effects of multiple stressors on wildlife is crucial for conservation.
• Fluoxetine (Prozac) is a common pharmaceutical contaminant with poorly understood ecological impacts.

Purpose of the Study:

• To investigate the independent and interactive effects of long-term fluoxetine exposure and acute temperature stress on guppy reproductive behaviors and activity levels.
• To assess the impact of environmentally relevant fluoxetine concentrations on fish behavior.
• To determine how cold and heat stress influence behavior in the presence or absence of pharmaceutical pollution.

Main Methods:

• Guppies (Poecilia reticulata) were exposed to environmentally realistic fluoxetine concentrations (38 or 312 ng/L) or a control for 15 months in a mesocosm system.
• Fish were subjected to acute temperature stress (cold: 18 °C, heat: 32 °C) or a control (24 °C) for 24 hours.
• Reproductive behaviors and activity levels were quantified to assess behavioral changes.

Main Results:

• No interactive effects were found between fluoxetine exposure and temperature stress on guppy behavior.
• Long-term fluoxetine exposure led to increased male coercive copulatory behavior.
• Cold-temperature stress significantly reduced activity levels and male reproductive behaviors in both sexes.

Conclusions:

• Both pharmaceutical pollution (fluoxetine) and temperature stress independently alter critical fitness-related behaviors in fish.
• These behavioral changes in guppies suggest potential shifts in population dynamics within contaminated ecosystems.
• Further research is needed to understand the long-term ecological consequences of combined environmental stressors.