Periodic Reporting for period 1 - AMAZON_MERCURY (Evolutionary adaptations to mercury pollution in avian bioindicators)
Reporting period: 2021-04-01 to 2023-03-31
The AMAZON_MERCURY project investigates the evolutionary changes caused by long-term exposure to mercury pollution in wild bird populations in the Peruvian Amazon using powerful genomic tools. It combines multiple fields or research (such as ecotoxicology and endocrinology) to generate new insights into the costs of environmental pollution, and the adaptations that allow surviving sublethal exposure to mercury. In the Peruvian southern Amazon, where artisanal goldmining results in contamination of the ecosystem with the toxic heavy metal mercury, understanding these processes will aid in estimating the costs to wildlife and nature, as well as to the human communities that are exposed to similar risks by being part of the same ecosystem. The findings of this study may also apply to additional areas of similar circumstances. By identifying the mechanisms by which birds cope with this long-term pollution, we can proceed to generating the means to mend these costs in humans and other species.
Our work so far has included developing the framework of the field study system that allowed collecting the necessary samples, complete samples processing and moving forward to analyzing the data. It involved developing a novel technique for capturing birds in a challenging set-up, including designing a specialized contraption for deploying mist-nets in dangerous waters. This effort produced many bird and environmental samples, in addition to historic specimens that allow us to understand how the ecosystem changed following the arrival of artisanal goldmining into the region.
Our findings indicate that mercury levels in some lake sediments correlate with artisanal goldmining activities, corresponding with known biochemical processes of ionic mercury methylation by sediment bacteria. Similarly, mercury levels in birds were highest in individuals captured in the unprotected areas (where goldmining is highest). When compared to historic specimens, pre-goldmining levels were significantly lower than contemporary levels, indicating that the source of the excess mercury in the environment is human induced. In addition, stress hormone levels were lower in birds with higher mercury loads, suggesting that higher sub-lethal mercury levels may cause a lessened stress hormone-recruiting response which inhibits the bird’s ability to respond to acute changes in the environment. We also sequenced several new genomes that will be made public shortly for the benefit of the scientific community.
Our findings indicate that mercury levels in some lake sediments correlate with artisanal goldmining activities, corresponding with known biochemical processes of ionic mercury methylation by sediment bacteria. Similarly, mercury levels in birds were highest in individuals captured in the unprotected areas (where goldmining is highest). When compared to historic specimens, pre-goldmining levels were significantly lower than contemporary levels, indicating that the source of the excess mercury in the environment is human induced. In addition, stress hormone levels were lower in birds with higher mercury loads, suggesting that higher sub-lethal mercury levels may cause a lessened stress hormone-recruiting response which inhibits the bird’s ability to respond to acute changes in the environment. We also sequenced several new genomes that will be made public shortly for the benefit of the scientific community.
Our current work involves analyzing the genomic characteristics of birds of several species and identifying the changes in their genome sequence and the genes that are being activated in response to elevated mercury levels. By comparing birds from non-polluted to polluted areas, we can determine the mechanism that allows them to survive despite living in a contaminated environment, as well as emphasize the costs of such pollution on the health and survival of animals and humans alike. By illustrating the short and long-term changes to birds, we can potentially alert local communities to the dangers of the continuous environmental mercury pollution, as we as to begin the exploration into potential solutions.