Fish and wildlife provide important information on the environmental impacts of mercury pollution and potential risks related to human health. Biomonitoring is the process of assessing the health of organisms and ecosystems and tracking changes in mercury risk and exposure over time.
The objective of the Minamata Convention on Mercury is to “protect the human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds.” Monitoring mercury exposure to humans and wildlife as outlined in Article 19 (including fish, sea turtles, birds, and marine mammals) will help the global community to meet requirements of the Convention moving forwards.
Local, Regional, and Global Biomonitoring: Understanding Mercury Exposure through Monitoring At-risk Species. This publication describes the who, what, how, why, and where of biomonitoring efforts as set forth in Article 19 of the Minamata Convention on Mercury. The booklet outlines the biomonitoring process in detail, and provides case study examples for taxa including fish, sea turtles, birds, marine mammals, and humans.
Mapping mercury (Hg) emissions and deposition only partly explains the spatial story of mercury pollution. Elemental mercury is converted to a more toxic and persistent organic form through the process of methylation, which occurs with the help of bacteria found primarily in wet areas. Methylmercury (MeHg) can then be bound in the food web where it can biomagnify and contaminate ecosystems.
Ecosystem Sensitivity is Key
Methylmercury concentrations in the food web depend on the sensitivity of the habitat to mercury input. Areas of high sensitivity and high mercury exposure are called biological mercury hotspots; they represent the places that will require the most attention by countries and global monitoring programs. These hotspots are crucial to identify, especially if they represent important food sources for people or if they contain threatened and endangered species.
The Role of Bioindicators
Fish and wildlife provide important information on the environmental impacts of mercury pollution and potential risks related to human and ecological health. Young fish (<1 year) can reflect rapid changes of environmental mercury loads, while long-lived predatory fish commonly consumed by humans may indicate concern for human health.
In terrestrial ecosystems, birds are effective bioindicators of mercury pollution. Their public appeal can also help highlight environmental concerns and convey complex messaging.
Mammals can represent both aquatic and terrestrial ecosystems. Some groups are highly relevant for human health purposes (e.g., toothed whales), while others are relevant indicators of ecological integrity, such as fish-eaters (e.g., otters) or invertebrate-eaters (e.g., bats).
Trophic Levels and Biomagnification of Mercury
Trophic levels are the feeding positions within the food web and are an important metric to track and understand human and ecological health concerns of methylmercury in biota. Methylmercury that bioaccumulates within individuals can pass from prey to predator, becoming more concentrated as it moves through trophic levels of the food web—a process called biomagnification.
Due to biomagnification, even small quantities of methylmercury in water can result in concentrations that are up to 10 million times higher in upper trophic level species. Each trophic level or step generally results in an increase of methylmercury of an order of magnitude. In freshwater and marine ecosystems, mercury monitoring programs should sample organisms in trophic levels 4 and 5 in order to optimize assessments.
BRI has developed a Global Biotic Mercury Synthesis (GBMS) database, the first of its kind, that is a compilation and synthesis of published fish, sea turtle, bird, and marine mammal mercury data collected from all over the world.
The GBMS database provides a standardized and comprehensive platform for understanding mercury concentrations in biota outlined in Article 19 of the Convention. Data from the GBMS database are presented in BRI's report, Mercury in the Global Environment.
BRI has collaborated with IPEN to conduct several global mercury studies focused on human exposure to mercury through seafood. Togegher BRI and IPEN have coordinated human hair and fish sampling efforts in 44 countries to date. The partnership between IPEN and BRI provides a rare opportunity to compile new and standardized mercury concentrations on a global basis that reflect the potential impacts of mercury on human populations around the world.
BRI is currently collaborating with UN agencies to develop future biomonitoring efforts across the globe to establish a baseline and examine temporal trends of mercury exposure to humans and the environment.
Above: Representatives from UN Environment and leaders in mercury research from around the world met in Ottawa, Canada, March 5-7, 2018, to discuss strategies for future global biomonitoring efforts.
Above: Expert Consultation for Biota and Soil Mercury Monitoring, as contributions to the EE Ad-hoc group, at the International Atomic Energy Agency in Monte Carlo, Monaco, May 13-14, 2019.
Download the following brochures to learn how you can participate in global efforts to monitor mercury in humans and seafood in your country. Each brochure outlines the sampling process and highlights how participation will help countries meet requirements of the Minamata Convention on Mercury.
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