Project Summary (1995-2000)

This research is examining the influence of previous exposure to a mixture of heavy metals (Cd, Cu, Pb, Zn) on molecular, population, and community responses to subsequent stress. Mechanisms responsible for enhanced tolerance by relating responses at the molecular and population level to changes observed at higher levels of organization (community) are being evaluated. Studies are being conducted using benthic macroinvertebrate populations and communities collected from the Arkansas River, a U.S. EPA Superfund site that has been polluted by metals for over 100 years. Studies conducted in collaboration with Dr. Barry Beaty (Project 5) are investigating molecular changes associated with increased production of metal-binding proteins. At the community level, scientists are assessing the relative importance of both intraspecific (physiological and/or genetic changes) and interspecific (replacement of sensitive species by tolerant species) tolerance mechanisms. This research is also investigating the effects of novel stressors (e.g., UV-b radiation, acidification) on previously-exposed and naive systems.