Reconstructing avian mercury concentrations through time using museum specimens from New York State

Area of Science:

• Environmental toxicology
• Avian ecology
• Biomonitoring

Background:

• Birds serve as crucial biological indicators of ecosystem health.
• Methylmercury (MeHg) is a potent neurotoxin with significant ecological impacts.
• Understanding historical MeHg exposure in wildlife is vital for conservation and risk assessment.

Purpose of the Study:

• To investigate temporal trends of methylmercury (MeHg) concentrations in bird feathers.
• To assess if feather MeHg levels reflect historical mercury (Hg) emission patterns.
• To evaluate MeHg exposure risks in six bird species breeding in New York State.

Main Methods:

• Analysis of feather MeHg concentrations from museum specimens spanning 1880-2016.
• Measurement of stable isotopes (δ15N) to infer diet and habitat.
• Comparison of temporal MeHg trends with historical Hg emission data.

Main Results:

• Feather MeHg concentrations positively correlated with δ15N, indicating a link to diet.
• Some individuals from four of six species exhibited feather MeHg levels exceeding known sublethal effect thresholds.
• Contrary to predictions, feather MeHg trends did not consistently align with historical Hg emissions and showed significant interspecific variation.

Conclusions:

• Historical MeHg exposure in birds is complex and not solely driven by emission patterns.
• High within-individual variation in feather MeHg may obscure temporal trends.
• This retrospective study highlights the need for nuanced biomonitoring approaches for mercury contamination.