David Lodge Ludmilla F., Stephen J., and Robert T. Galla Professor; Director, ECI

Conservation Biology: Freshwater Ecology, Invasive Species, Risk Analysis, and Environmental Policy
David Lodge

Research Interests

Many global environmental changes have very large impacts on biodiversity, on community structure, and on the function of terrestrial and aquatic ecosystems. Current research in my lab focuses on conservation biology, especially on the overlapping spheres of interest described below, all of which relate to current global changes. My students, postdocs, and I have conducted field work in the inland lakes and streams of northern Indiana/southern Michigan, UNDERC in the upper peninsula of Michigan, the Great Lakes, the coastal plain of North Carolina, Denmark, and Kenya. Current funding comes from NSF, EPA, NOAA Sea Grant, USDA, and the US Department of Education.


Freshwater Ecology

Our long-term interest in food webs and the impacts of consumers on their resources continues. We focus especially on predatory-prey and plant-herbivore interactions. A major overall question motivating this area of research is “how does the structure of communities impact lake and stream ecosystem function?” Consumer species that we have studied in detail include algivorous snails, herbivorous waterfowl, predacious fishes, and omnivorous crayfishes. Our experiments at the UND Environmental Research Center (UNDERC) have recently changed the tradition in limnology of separately studying the pelagic and benthic habitats in lakes. We have demonstrated, for example, that benthic algal production often compensates for phytoplankton production; that macrophytes provide a predation refuge to Daphnia ; and that when crayfish clearcut the lake bottom, benthic productivity declines and lake-wide energy flows shift. In general, our studies demonstrate that consumer-resource interactions, especially between benthic and pelagic habitats, powerfully influence freshwater community structure and ecosystem function.

Most recently, we are examining the role and interactions of climate, watershed vegetation, and the structure and function of food webs in linked lake-stream systems. Specifically, we are focusing on the controls of the quantity and quality of dissolved organic carbon (DOC) in affecting behavior and populations of freshwater algae and invertebrates.

Invasive Species Biology and Bioeconomics

In recognition of the extreme importance of invasive species in driving declines in native biodiversity and changes in ecosystem function, invasion biology has emerged in recent years as a central focus of conservation biology. Because these same species threaten human health, and cause enormous financial damage to crops, forests, and industrial infrastructure, they are also of critical importance in environmental economics. Together with our economist collaborators, we are leading the way in developing the capacity to forecast invasions and quantify the interaction between invasions and the economic forces that drive and respond to invasions. One overall question is “can we forecast the introduction, establishment, dispersal, and impact of nonindigenous species on native species and ecosystems?” We are studying the pathways by which alien species are being introduced; the interactions that alien species have with native species, and how those interactions affect community and ecosystem function. We are also conducting extensive statistical analyses of alien and native species in the Great Lakes to discover characteristics that distinguish invasive from non-invasive species, and species that become nuisances from those that do not. In addition, we are using stochastic population models to estimate the risk of establishment of alien species from unintentional releases like those that commonly occur in ships’ ballast water.

We are combining ecological and economic models to provide guidance to societal investments invasive species management-for example, how much should be invested in prevention vs. control. Our first papers on this topic demonstrate that it would be cost-effective to invest much more heavily in preventing future invasions rather than waiting and responding once an invasion happens.

Ecological Risk Analysis

Our work in invasion biology is one example of our work on risk analysis (which combines risk assessment and risk management). In a second area of ecological risk analysis, we are collaborating with colleagues in chemical engineering to quantify the ecological risk posed by ionic liquids, a new class of ionic compounds that are liquid at room temperature. As solvents, these compounds are likely to be adopted by a number of industries in the near future. They are attractive as “green chemicals” because their adoption would certainly reduce air pollution as they replace the organic solvents now in use. However, the potential for water pollution has not assessed, and the possibility therefore exists of another MTBE-like episode-where one form of environmental pollution is exchanged for another. In order to prevent that, we are testing a number of alternative forms of the ionic liquids for their ecotoxicity to single- and multiple-species freshwater communities. The ecological results in turn are guiding the research in chemical engineering toward more environmentally benign combinations of ions. This is a completely novel and exciting area of interdisciplinary research.

Global Changes and Biodiversity

Much of our research in freshwater ecology involves global changes, but in the past our study of those issues has been largely local and regional. More recently, we have scaled up our quantification of these issues to the global level, focusing on the impact on freshwater biodiversity of climate change (as it affects surface water availability), irrigation, land use, acidification, and eutrophication. For example, on a global scale, we are forecasting likely declines in fish species number in watersheds that are predicted to become dryer under one or more future scenarios of economic, political, and social development.

Environmental Ethics and Policy

Much of our on-going research has direct application to natural resource management, policy, and environmental ethics. Thus, in the last few years, we have been conducting research at both very specific levels of policy (how much should society invest in preventing the further spread of zebra mussel?) and at the more general levels of intersection of science, theology, and environmental ethics. For example, we organized a conference and subsequently produced a book (Religion and the New Ecology: Environmental Prudence in a World in Flux, 2006) that focused in part on the question, “how should ethical prescriptions for natural resource management change when theologians and ethicists recognize that nature has always and will always be changing, even apart from the rapid anthropogenic global changes discussed above?” We were motivated by the belief that it is critical that scientists and ethicists better understand each other’s ways of thinking and keep current in each discipline, at least through interdisciplinary conversation.


Selected Publications

  • Lodge, D.M. and Kristin Shrader-Frechette. 2003. Nonindigenous species: ecological explanation, environmental ethics, and public policy. Conservation Biology 17:31-37.
  • Drake, J.M. and D.M. Lodge. 2004. Global hotspots of biological invasions: evaluating options for ballast-water management. Proc. R Soc London B 271:575-580.
  • Sponberg, A.F. and D.M. Lodge. 2005. Seasonal belowground herbivory and a density refuge from waterfowl herbivory for Vallisneria americana. Ecology 86:2127-2134.
  • Sala, O., D. van Vuuren, H.M. Pereira, D.M. Lodge, J. Alder, G. Cumming, A. Dobson, V. Wolters, M. Xenopoulos, A.S. Zaitsev, M. Gonzalez Polo, I. Gomes, C. Queiroz, and J. Rusak. 2005. Biodiversity across scenarios, Ch. 10 (pp. 375-410) in S.R. Carpenter, P.L. Pingali, E.M. Bennett, and M.B. Zurek (eds), Ecosystems and human well-being: Scenarios, volume 2, Millennium Ecosystem Assessment.
  • Leung, B., D. Finnoff, J.F. Shogren, and D.M. Lodge. 2005. Managing invasive species: rules of thumb for rapid assessment. Ecological Economics 55:24-36.
  • Xenopoulos, M.A., D.M. Lodge, J. Alcamo, M. Marker, K. Schulze, and D. van Vuuren. 2005. Scenarios of freshwater fish extinctions from climate change and water withdrawal. Global Change Biology 11:1557-1564.
  • Lodge, D.M. S.K. Rosenthal, K.M. Mavuti, W. Muohi, P. Ochieng, S.S. Stevens, B.N. Mungai, and G.M. Mkoji. 2005. Louisiana crayfish (Procambarus clarkii) (Crustacea: Cambaridae) in Kenyan ponds: non-target effects of a potential biological control agent for schistosomiasis. African Journal of Aquatic Science 30:119-124.
  • Drake, J.M. and D.M. Lodge. 2006. Allee effects, propagule pressure and the probability of establishment: risk analysis for biological invasions. Biological Invasions 8:365-375.