Dragonfly Mercury Project: In 2012, researchers began collecting dragonfly larvae to detect mercury contamination in protected waters. Thirteen years later, 21,000 samples helped create a model that can estimate mercury risks in freshwater without testing every stream.
Researchers from the US Geological Survey and the National Park Service used data from 21,000 Dragonfly larvae These were collected over 13 years to develop a national model that can estimate Hazards of mercury in fresh water In areas where direct monitoring data may not be available, according to the report.
The model combines measured mercury concentrations in dragonfly larvae with commonly collected information about water chemistry and landscape characteristics. Researchers say it could help scientists, resource managers and policy makers assess mercury risks and identify places where additional monitoring may be needed, according to the USGS report.
13 years of dragonfly data helped build the model
The model was developed using data collected through Mercury Dragonfly Projecta national initiative involving researchers, park staff, and public participants.
Over the course of 13 years, the project collected 21,000 dragonfly larvae from freshwater ecosystems across the United States. The data gave researchers information about mercury concentrations across different landscapes.
Dragonfly larvae are useful indicators Mercury contamination Because they live in fresh water and are found in a wide range of environments. The levels of mercury in their tissues can provide information about exposure within the ecosystems in which they live.
The model can estimate mercury risks in untested areas
One of the main advantages of the new model is that it can estimate mercury levels in areas where direct monitoring data are not available. The model combines mercury concentrations in dragonfly larvae with information about water chemistry and land cover to estimate how mercury risks vary across landscapes.
This may be especially useful on protected lands and in remote areas, including national parks, wildlife refuges and national forests, where mercury monitoring can be time-consuming and expensive.
The model also provides insight into factors that may influence mercury methylation, the process by which microorganisms convert inorganic mercury into a more toxic organic form, researchers say.
Previous monitoring has shown that mercury levels can vary greatly
Long-term Dragonfly Mercury Project data used to develop the model showed that mercury concentrations can vary greatly between sites.
In the previous national assessment, average mercury concentrations at the site with the highest levels were 135 times higher than at the site with the lowest levels.
The project also found differences between types of water bodies. Dragonfly larvae from rivers and streams generally contain higher mercury concentrations than those found in ponds and lakes.
Mercury concentrations also differed between environmental regions. After accounting for habitat type, dragonfly larvae from North American deserts had the highest average mercury concentrations, while those from the Great Plains had the lowest levels.
These previous results have demonstrated the importance of environmental and landscape conditions when assessing mercury risks.
Dragonfly mercury can provide clues about fish
Previous research by the Dragonfly Mercury Project also found that mercury concentrations in dragonfly larvae could predict mercury levels in fish and amphibians collected from the same sites.
This makes dragonfly larvae useful for assessing mercury exposure across freshwater ecosystems, especially because they are present in many types of water bodies.
This research found that about 80% of the mercury found in dragonfly larvae was methylmercury. Because measuring methylmercury can be more time-consuming and expensive, the researchers found that measurements of total mercury in dragonfly larvae can be used to model the risks posed by methylmercury.
The model can guide future tests
The new model could help scientists and resource managers identify areas where additional water and fish testing might be useful.
It can also provide information to help advise on fish consumption and identify communities that may face higher mercury exposure where monitoring data is limited.
Specifically, the researchers noted that this could help identify potential risks to some tribal nations near protected lands that rely on native fish for food.
“By predicting mercury risks in freshwater ecosystems on or near protected lands, the model can provide decision-makers with data to guide water and fish testing efforts and help inform fish consumption advisories that protect the public,” said Christopher Kotalik, a USGS research ecologist and lead author of the study.
“The new predictive model for mercury will help park managers assess mercury risks in freshwater bodies of national parks and guide research, monitoring and management decisions for national parks,” said National Park Service ecologist Colleen Flanagan Britz, a co-author.
The model can be used in remote ecosystems
The model can be applied to protected lands and remote areas far from urban and industrial sources of mercury.
The researchers also say it could provide insight into how land management and restoration activities, including controlled burning used to manage forests, are changing mercury risks.
The national scale of the model represents an important step beyond previous mercury forecasting methods that were limited to smaller local or regional areas.
