The Tropics refers to the equatorial region of Earth that extends across five continents including parts of Central and South America, Africa, Asia, and Australia and includes marine ecosystems between the Tropics of Cancer and Capricorn. Tropical ecosystems are synonymous with biodiversity. Nearly two-thirds of all known species inhabit these dense rain forests, tropical savannas, coastal mangroves, and rich coral reefs.
Program Director: David Evers, Ph.D.
The health of tropical ecosystems is being impacted by multiple stressors ranging from deforestation and the degradation of habitats to climate change. The conservation of these ecosystems is one of the greatest ecological challenges the global community will face in the coming decades. BRI and the Tropical Program contribute to this effort through participation in collaborative research and conservation initiatives designed to identify new and emerging stressors and to inform stakeholders and policymakers about our science.
BRI’s Tropical Program is involved in a wide variety of research and conservation initiatives intended to improve our understanding of how environmental contaminants impact ecosystem and human health in the tropics. Many of these initiatives are interdisciplinary in nature and include collaborators from national agencies within tropical countries as well as local and international conservation organizations. Several BRI programs including the Songbird, Mammal, and Wetlands Programs contribute to these efforts.
Fish consumption is the primary pathway through which humans become exposed to mercury. Many national and international health organizations recognize the risks associated with a diet high in fish and international guidelines for the maximum amount of Hg in fish have been established. BRI's Tropical Program works with local researchers in multiple countries to identify 'hotspots' of mercury accumulation where mercury concentrations represent a risk to human and ecosystem health. Below are representative research projects with a focus on fish and human health:
Bats represent a significant component of mammalian diversity in the tropics, with approximately 1,200 species currently known. Our research with tropical bats incorporates traditional ecological approaches for understanding population and community composition as well as ecotoxicology and exploring the utility of bats as bioindicators of heavy metal contamination in tropical ecosystems. BRI currently coordinates a network of Neotropical researchers who focus on collecting and analyzing tissue samples for mercury concentrations to better understand the risks of exposure in a variety of species across multiple ecosystems. Below are representative projects with a focus on bats and ecosystem health:
Mercury is a global pollutant that has the potential to adversely affect hundreds of bird species across the western hemisphere. For species that migrate to Central and South America, this means that individuals may encounter mercury contamination on their breeding grounds, along migratory routes, and on their wintering grounds. BRI is working with local bird researchers in Belize, Costa Rica, and Nicaragua to assess the risk of mercury exposure in neotropical migratory songbirds.
Artisanal and small-scale gold mining (ASGM) is responsible for an estimated 727 tonnes per year of mercury emissions to the atmosphere with an additional 800 tonnes per year of mercury releases to land and water, making it the largest anthropogenic source of mercury. The ASGM sector employs an estimated 10-15 million people in more than 70 countries worldwide. BRI's Tropical Program is working with international development organizations, mining engineers, and conservation organizations to develop strategies for reducing the use of mercury by small-scale miners. Representative projects include:
The Mesoamerican Reef is the largest coral reef in the Western Hemisphere and extends more than 1,000 km along the coastlines of Mexico’s Yucatán Peninsula, Belize, Guatemala, and Honduras. In previous research, BRI and collaborating scientists documented high mercury concentrations in marine fishes. Current research focuses on measuring fish mercury concentrations sampled from the region’s major watersheds in an effort to identify potential terrestrial sources of mercury that are delivered to the coastal zone and out onto the reef.
Mexico straddles the Tropic of Cancer and is considered a "megadiverse" nation by the United Nations Environment Programme. BRI's work in Mexico utilizes our capacity to assess mercury in the environment to assist local governments with identifying species and ecosystems at risk of mercury exposure. In addition, BRI is active in marine conservation efforts focusing on plastics pollution and the human and ecosystem risks associated with plastic debris.
One representative research project is: Limpia Guerrero 2013: A Pilot Study of Environmental Contaminants in México
BRI participated in the sub-regional workshop for Central American countries in support for the ratification and early implementation of the Minamata Convention on Mercury, a global treaty to protect human health and the environment from the adverse effects of mercury. The workshop was held in Mexico City from November 26-28, 2014.
Major highlights of the Convention include a ban on new mercury mines and the phase-out of existing ones, control measures on air emissions, and regulations for artisanal and small-scale gold mining (ASGM). BRI has begun several projects related to this work.
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