The Production and Transfer of Methylmercury within Terrestrial Food Webs across the Northeastern Landscape
Atmospheric mercury is generated from coal-fired power plants, other human sources, as well as natural sources. Once deposited to soil, natural processes create methylmercury, a form that easily accumulates to toxic levels as it moves through food webs. Mercury is a neurotoxin shown to impact behavior, growth, and reproductive success of wildlife. Detrimental effects of mercury contamination have been extensively documented in aquatic ecosystems including fish, but it is equally important to understand impacts of mercury on organisms in the surrounding terrestrial landscape. Blood mercury concentrations measured in several northeastern songbird species are high enough to cause adverse health effects. It is suspected that mercury is transferred to top predators, such as songbirds, by invertebrate prey species, such as insects.
NSRC researchers explored atmospheric mercury deposition across the Adirondack Park region of New York State and discovered that while variation in deposition is large across the area, locations in the southwest and northern part of the Park are subject to higher deposition rates. Regional mercury levels within soils were highest for the Adirondack Park, where soil moisture and acidity were found to enhance production of methylmercury.
Invertebrate and songbird communities inhabiting sensitive coastal and wetland ecosystems were found to have mercury levels elevated to concentrations that can impair reproductive success. Chemical analyses demonstrated the bio-magnification of methylmercury from herbivores (plant-eaters), such as insects, to their predators, such as songbirds, within Sphagnum bogs. Ideally, these findings can direct future research and monitoring efforts designed to examine critical issues of air quality, environmental integrity, and wildlife health in the Northern Forest region.