Worldwide amphibian declines and increased reports of amphibian malformations have prompted the United States Department of Interior (DOI) to initiate an Amphibian Research and Monitoring Initiative (ARMI). Regional ARMI programs are planned throughout the United States. Acadia National Park (ANP) is serving as a long-term intensive amphibian monitoring index site. This proposed research includes defining relationships of stream-dwelling salamanders and cross-scale habitat composition (within-stream to watershed-scale), with the intent of using salamander population counts and trends as indicators of park stream conditions. Although mercury contamination in lotic ecosystems in the Park is well-documented and is a result of non-point atmospheric deposition, levels in streamside salamanders are unknown. This study will provide insights into mercury bioaccumulation levels in stream-side salamanders, how they contribute to mercury cycling and transfer in both lotic and terrestrial food webs, and the potential for a decline of stream-dwelling biota with increasing mercury contamination. Another aspect of this research includes a survey of four-toed salamanders, a species of concern in Maine, Massachusetts, and Vermont. The distribution of four-toed salamander has decreased throughout its range due to wetland loss associated with land clearing and development. This species may require mature hardwood or conifer forests and fishless wetland breeding sites, making it vulnerable to habitat disturbance. Our objective is to document the distribution and habitat associations of this species within ANP, and develop predictive models of their potential occurrence in the Park based on the documented local- and landscape-scale habitat associations.