The Effect Of Methylmercury On The Auditory Brainstem Response In Domestic Zebra Finches (Taeniopygia Guttata)

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Wolf, Sarah Elizabeth
thesis / dissertation description
With global urbanization on the rise, human activities continue to threaten the functionality of auditory communication in birds through induced change to vocalizations, the acoustic landscape, and hearing ability. One human-associated pollutant potentially affecting auditory communication is mercury, which is released into the environment through industrial emissions and is correlated with markers of global climate change. Already, mercury has been implicated in mammalian high-frequency hearing impairment; however, the effect of mercury on avian hearing ability is unknown. In this study, we examined whether dietary mercury exposure affected hearing ability in domestic zebra finches using the auditory brainstem response (ABR), which measures the peripheral auditory pathway’s response to sound. Our results revealed that mercury-exposed birds exhibited elevated hearing thresholds, lowered amplitudes, and longer latencies compared to non-exposed birds, all of which argue that methylmercury is degrading hearing ability in domestic zebra finches. When these effects are considered in combination with other anthropogenic stressors that are often correlated with mercury contamination in the field, the hearing impairments we document here could substantially degrade avian auditory communication in nature. This study presents the first evidence of mercury-induced hearing impairment in birds. If used as a model for vertebrate communication pathways, this and related research could elucidate how mercury-induced physiological responses associated with hearing could impact communication abilities and fitness in the field.