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Adverse effects from environmental mercury loads on breeding common loons
David C Evers1, Lucas J Savoy, Christopher R DeSorbo
1BioDiversity Research Institute, 19 Flaggy Meadow Road, Gorham, ME 04038, USA. david.evers@briloon.org
Ecotoxicology (London, England)
|October 3, 2007
Summary
Elevated mercury levels in aquatic ecosystems are harming common loons (Gavia immer). This study shows increasing mercury burdens negatively impact loon health and reproduction, creating population sinks.
Area of Science:
- Environmental Toxicology
- Wildlife Ecology
- Ecotoxicology
Background:
- Anthropogenic mercury (Hg) inputs have risen, increasing methylmercury (MeHg) in aquatic systems.
- MeHg poses risks to ecological and human health, necessitating bioindicator studies.
Purpose of the Study:
- To assess the impact of MeHg body burdens on common loons (Gavia immer) as an indicator species.
- To establish adverse effect thresholds for MeHg in adult loons.
Main Methods:
- Utilized an 18-year spatio-temporal dataset with nearly 5,500 loon Hg measurements.
- Monitored multiple endpoints: behavior, physiology, survival, and reproductive success.
- Measured Hg levels in blood and feathers to establish effect thresholds.
Main Results:
- Common loon Hg body burdens increased by 8.4% annually.
- Elevated MeHg correlated with aberrant behavior (lethargy, abnormal incubation) and physical asymmetry.
- Highest risk loons produced 41% fewer fledged young; established thresholds at 3.0 ug/g (blood) and 40.0 ug/g (feathers).
Conclusions:
- Mercury contamination is a significant stressor, creating breeding population sinks in some regions.
- Standardized monitoring is crucial to track ecosystem responses and identify other potential population sinks.
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