- Driscoll, Charles T.
A potent neurotoxin, mercury (Hg) has been shown to impact the behavior, growth and reproductive success of wildlife through bioaccumulation within food webs. The detrimental effects of mercury contamination have been extensively documented in aquatic ecosystems, but it is equally important to understand the impacts of mercury deposition, methylation and bioaccumulation on biota within the adjacent, surrounding landscape. Unfortunately, relatively few studies have focused on the mechanisms of bioaccumulation of mercury in terrestrial ecosystems. However, preliminary measurements have shown blood mercury concentrations in several Northeastern songbird species are elevated to levels where adverse physiological effects are evident. It is hypothesized that mercury is transferred to top predators, such as songbirds, by invertebrate, prey species located at lower trophic levels within terrestrial systems.
The overall goal of this research was to improve understanding of the fundamental mechanisms of methylmercury (MeHg) transfer in terrestrial foodwebs. The specific objectives were to: conduct a synthesis of existing datasets on the relationships between abiotic and biotic mercury concentrations in terrestrial foodwebs; conduct stable isotope analysis to identify and evaluate trophic pathways for methylmercury bioaccumulation in terrestrial habitats; and link the results with regional ecological studies to develop a more comprehensive understanding of the effects of mercury deposition across the Northeastern landscape.
Information compiled through a collaboration between Syracuse University and BioDiversity Research Institute examined the relationship between mercury deposition across the landscape and its subsequent movement through terrestrial systems. Modeling of atmospheric mercury deposition across the Adirondack region of New York State indicated that while variation is large across the area, geographic 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 and variables such as soil moisture and pH were found to influence the production of methylmercury. The cycling and availability of mercury is dependent upon habitat type and drives mercury concentrations at the base of the food chain and bioaccumulation within associated foodwebs. As a result, invertebrate and songbird communities inhabiting sensitive coastal and wetland systems were found to have mercury levels elevated to concentrations that can negatively impact reproductive success. Stable isotope analyses demonstrated the transfer and biomagnification of methylmercury from herbivores to predators within Sphagnum bog habitats. Ideally, the results from this project will be used as a foundation to direct future research and monitoring efforts designed to examine critical issues of air quality, environmental integrity and wildlife health in the Northern Forest region.