Johanna Kraus, Ph.D.


Johanna M. Kraus, Ph.D. is a Research Ecologist with the U.S. Geological Survey Columbia Environmental Research Center where she applies principles of community ecology to study the effects of chemical contaminants on food webs, biodiversity and environmental health in aquatic and terrestrial ecosystems. She began her career with the USGS in 2011 researching how trace metals from acid rock drainage impact adult aquatic insect emergence and contaminant flux to terrestrial insectivores near mountain streams. Since then she has improved understanding of how chemical contaminants impact linked aquatic-terrestrial food webs using large empirical field studies, laboratory manipulations and conceptual modelling. Dr. Kraus received her B.A. in Biology from Brown University and Ph.D. in Biology from the University of Virginia.  


    • Ph.D., Biology, University of Virginia, 2006
    • B.A., Biology, Brown University, (honors, magna cum laude), 1998

    Professional Appointments

    • Research Ecologist, U.S. Geological Survey, 2016 - present
    • Mendenhall Research Fellow, U.S. Geological Survey 2011- 2015
    • Post-doctoral Researcher, Biology, Virginia Commonwealth University, 2007-2010  
    • Visiting Assistant Professor, Biology, Washington and Lee University, 2006-2007
    • National Science Foundation EAPSI Fellow, Japan, 2006
    • National Science Foundation Graduate Research Fellow, 2002-2005  
    • Teaching Assistant, University of Virginia, 2002-2005  
    • Presidential Fellow, University of Virginia, 2000


    Projects include

    Predicting Effects of Contaminants on Cross-Ecosystem Linkages 

    As part of their life cycle, aquatic insects transition from aquatic larvae to terrestrial adults, thereby linking freshwater ecosystem processes and terrestrial insectivore dynamics. These linkages are strongly affected by contamination of freshwater ecosystems, which can reduce production of adult aquatic insects (i.e., emergence), increase contaminant concentrations in adult insect tissues, and alter contaminant flux to terrestrial ecosystems. To predict these impacts of contaminants on adult aquatic insects, I developed a heuristic framework using physicochemical properties of contaminants to categorize these effects and am collaborating with leading scientists in the field to generate testable predictions using models and empirical data. Outlets include a cluster of papers (Freshwater Science) and edited volume (Springer Scientific). 

    Food Web Dynamics and Biotransport of Metals in Mineralized Ecosystems 

    Trace-metal contamination of aquatic ecosystems is a major health and environmental concern globally, leading to alterations of aquatic communities, decreased fisheries and bioaccumulation in higher trophic levels. In the Rocky Mountains, we are examining the role of trace metal pollution in determining importance of resource subsidies (adult aquatic insects and terrestrial inputs) for riparian and aquatic predators, and the flux of metals through these foods webs.

    Pesticides, Pollinators and Aquatic insects in Agricultural Ecosystems

    Current-use pesticides have been implicated in large scale decline of insects and their consumers. These projects investigate the effects of current-use pesticides and land use on pollinator diversity and health as well as the uptake and export of pesticides from the aquatic environment in adult aquatic insects that emerge from agriculturally impacted wetland ecosystems.  

    Restoration and Valuation of Natural Resource Injuries in Linked Aquatic-Terrestrial Ecosystems

    Contaminants have complex effects on communities and food webs in linked aquatic-terrestrial ecosystems. For example, metals from historical mining operations can indirectly impact fish diet by reducing aquatic resource availability. In these contaminated headwater streams, fish populations are sustained by inputs of terrestrial insects, possibly mediating impacts of aquatic injury. Furthermore, metals and other contaminants can kill larval aquatic insects leading to declines in emergence of flying adult aquatic insects such as mayflies and midges. This loss of flying insects eliminates an important and nutritious food source for terrestrial insectivores such as birds and bats. Natural resource injury cases have long grappled with cross-ecosystem injuries and food web connections.  How does terrestrial contamination affect aquatic systems, and vice versa?  Conversely, what are the expected gains from terrestrial restoration to aquatic systems, and vice versa?  Are these relationships quantifiable? This project will work to develop a rubric for applying heuristic models for predicting cross-ecosystem effects of contaminants to such cases.