Context-specific behavioural changes induced by exposure to an androgenic endocrine disruptor

Area of Science:

• Environmental Science
• Ecotoxicology
• Endocrinology

Background:

• Pharmaceutical contaminants, including 17β-trenbolone, are increasingly detected in global ecosystems.
• These compounds pose environmental risks due to conserved drug targets, persistence, and bioaccumulation.
• Limited research exists on pharmaceutical impacts on animal behavior across fitness contexts.

Purpose of the Study:

• To investigate the effects of 17β-trenbolone exposure on eastern mosquitofish behavior and reproductive traits.
• To assess impacts on boldness, activity, exploratory behavior, reproductive association, sperm function, and morphology.

Main Methods:

• Wild-caught male eastern mosquitofish were exposed to a field-realistic level of 17β-trenbolone for 21 days.
• Behavioral assays included novel environment tests and reproductive association tests.
• Sperm function (viability, motility) and quantity were analyzed using computer-assisted sperm analysis.
• Morphological traits (mass, length) were measured.

Main Results:

• No significant effects on boldness, activity, or exploratory behavior were observed.
• 17β-trenbolone exposure reduced reproductive association behavior in males.
• While direct sperm traits were unaffected, exposure altered the relationship between male morphology and sperm function.
• Exposed males showed increased mass relative to length.

Conclusions:

• Field-realistic 17β-trenbolone exposure induces subtle but significant trait alterations in male fish.
• These include context-specific behavioral changes, disrupted morphology-sperm function trade-offs, and altered morphology.
• Such changes have potential implications for exposed wildlife populations.