Superfund Research Program
Trophic Transfer of Toxic Metals in Aquatic Food Webs
Project Summary (2000-2005)
The goal of this project is to develop a mechanistic model to explain variation in metal burdens for four potentially toxic metals (As, Hg and methylmercury (MeHg), Zn and Cd) in plankton and fish. A variety of systems arising from differences in the food web structure and the ability of particular taxa to accumulate, magnify or dilute metals are being examined. Researchers are characterizing the metal trophic transfer pathways in the field and testing whether the transfer to fish diminishes as zooplankton complexity increases. The strength and consistency of specific zooplankton taxa as conduits of metals to fish is being determined. Researchers are also testing whether increasing algal productivity decreases the movement of different metals to top trophic levels. And finally, general and specific biomarkers are being developed to investigate the environmental relevance of molecular responses to metal stress in natural field populations. This research is leading to development of more effective methods to estimate, from taxa-specific properties, the differences in how metals are transferred within food webs.