Tali Magory Cohen
Ecological Genomics, Evolutionary Ecology, Conservation Biology
Amazon Mercury
MSCA project at the University of Copenhagen & The University of California, Davis
The AMAZON_MERCURY project investigates the evolutionary changes caused by long-term exposure to mercury pollution in wild bird populations in the Peruvian Amazon.
It combines multiple fields of research (such as ecological genomics, 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.
An artisanal goldmining operation in Madre de Dios, Peru.
Our research
We study the impact of mercury pollution on birds in the Peruvian Amazon by investigating the link between mercury pollution in the environment, mercury levels in the birds, bird fitness (how healthy they are) and the genomic mechanisms that may be acting to allow birds to survive in polluted environments. We combine field work, laboratory analyses and advance bioinformatics to integrate our findings.
Our work has included 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.
Sampling birds in an oxbow lake in the Madre de Dios region in Peru.
What have we found so far?
Some patterns already emerge from the data we collected that show a significant impact of goldmining activities on birds in unprotected areas, mainly through the effect of mercury contamination. Here are a few preliminary key points:
Mercury (metyhl-mercury) levels were significantly higher in lake sediment in unprotected areas than in semi-protected (communal reserve) and protected areas. This is likely the result of bacteria present in the sediment that methylate ionic mercury (Hg2+) into metyhl-mercury, a more toxic species of mercury, which can be bioaccumulated and biomagnified up the food chain.
The same trend appears in mercury found in bird tissue. Birds captured in unprotected areas had the highest mercury loads compared with birds from semi-protected or protected areas. Moreover, guild (i.e., diet) affects mercury levels as well: piscivores (fish eaters) exhibited the highest mercury levels, followed by insectivores (insect eaters) and granivores (see eaters).
High mercury levels were also negatively correlated with birds' corticosterone levels. Corticosterone is a hormone that is activated during stress response to allow the body react properly, and low levels of it in certain scenarios suggest that a constant stress-inducing factor is inhibiting recruitment of corticosterone.
These changes also affected the expression of genes in birds. Differential Expression analysis showed variations in gene expression between individuals from unprotected and protected areas in three species of birds tested - the green kingfisher (Chloroceryle americana, a piscivore), the white-winged swallow (Tachycineta albiventer, an insectivore) and the red-capped cardinal (Paroaria gularis, a granivore). This pattern suggest that mercury affects which genes are being activated in birds exposed to high mercury levels.
Setting up mist-nets with our new technique in Cocha Cashu, Manu national park, Peru.
Our team
Many individuals have contributed to our work and we are proud to collaborate with local biologists as well as colleagues from around the world. Primarily the Gilbert group at the Globe Institute at the University of Copenhagen and the Bay lab at the University of California Davis have supported this project.
Our major partner is Dr. Adi Barocas from the San Diego Zoo Wildlife Alliance, whose Team Lobos works closely with our team.
Other collaborators include Prof. Elsie Sunderland (Harvard University), Prof. Michael Romero (Tufts University), Prof. Kristen Ruegg (Colorado State University), and Dr. Antton Alberdi (The Globe Institute).
Our field team includes brilliant Peruvian scientists and crew (including Victor Sánchez Cabrera, from IIECCO), and we are often joined by experienced volunteers.
Team Aves and Team Lobos, July 2021.
This project has received funding from the European Union's Horizons 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 896149.