Project Summary (1995-2000)

This project assesses natural variation in bioaccumulation and biomagnification of potentially toxic metals in lakes throughout the Northeastern region of the United States. Metals that vary with respect to their potential for bioaccumulation in natural systems are being compared. The focus is on the metals cadmium, mercury, arsenic, and lead, because all are contaminants of Superfund sites, and as such are the focus of other projects in this program. All are also hypothesized for different reasons to be found at elevated levels at different places in the Northeast, suggesting natural levels in aquatic ecosystems and potential health related hazards may vary regionally. Mercury is of particular concern because it bioaccumulates in fish tissue, and elevated levels have recently been found in a number of remote lakes that are not associated with local sources of contamination. The overall goals are to establish baseline data on levels of potentially toxic essential and non-essential metals in organisms throughout the food webs of natural lake ecosystems, and compare and contrast metal levels in organisms from lakes which vary with respect to food web complexity, proximity to urban centers or Superfund sites, and thermal regimes. These factors can alter the processes of bioaccumulation and biomagnification, affect the diversity and structure of aquatic food webs, and ultimately influence the potential for human exposure to metals via ingestion of fish.