Ecological Indicators 4 (2004) 245–253 Plankton respiration and biomass as functional indicators of recovery in restored prairie wetlands Paul M. Mayer a,∗ , Robert O. Megard b , Susan M. Galatowitsch c a U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 919 Kerr Research Drive, Ada, OK 74820, USA b Department of Ecology, Evolution and Behavior, University of Minnesota-Twin Cities, St. Paul, MN 55108, USA c Departments of Horticulture and Landscape Architecture, University of Minnesota-Twin Cities, St. Paul, MN 55108, USA Accepted 25 March 2004 Abstract Reliable ecological indicators of wetland integrity are necessary for assessing recovery of restored wetlands; yet, little consensus currently exists on which indicators are most appropriate. We employed indicators derived from simple, standard measures of ecosystem function selected on the basis of ecological succession theory developed by [Science 164 (1969) 262; Bioscience 35 (1985) 419], which suggests that respiration:biomass ratios should increase in disturbed systems due to the diversion of energy from growth to maintenance. This hypothesis holds potential for the development of a simple ecological indicator and therefore was tested among prairie wetlands restored after drainage disturbance. No difference was observed in respiration:biomass ratios in restored wetlands and reference wetlands designated as controls. Plankton respiration or biomass may be poor indicators of disturbance because plankton responds quickly to re-establishment of a wetland hydrology regime and/or because different plankton species may have redundant function. We suggest employing more revealing assessment techniques that employ simultaneous examination of ecosystem structure and function to better characterize subtle or lingering effects of wetland disturbance after restoration. Published by Elsevier Ltd. Keywords: BOD; Biomass; Community respiration; Ecological indicator; Recovery; Restored wetland 1. Introduction Assessing ecosystem integrity is critical to measur- ing the performance and recovery of restored ecosys- tems. Currently, no consensus exists on which ecolo- gical indicators are reliable for any ecosystem or under what conditions, they should be applied (McKenzie et al., 1995; De Leo and Levin, 1997). This dilemma is ∗ Corresponding author. E-mail addresses: mayer.paul@epa.gov (P.M. Mayer), galat0001@tc.umn.edu (S.M. Galatowitsch). also true for wetland ecosystems, either natural or cre- ated (Adamus, 1995, 1996; Galatowitsch et al., 1998; Hruby, 2001; Campbell et al., 2002). Furthermore, although numerous indicators and metrics have been devised to assess the integrity of wetland ecosystems, only a few attempts have been made to use these indi- cators to assess recovery in restored wetlands (Delphey and Dinsmore, 1993; Galatowitsch and van der Valk, 1996; Mayer and Galatowitsch, 1999, 2001). Elimi- nating indicators as unreliable or insensitive will be part of any successful process for identifying useful ecological indicators. One successful approach to 1470-160X/$ – see front matter. Published by Elsevier Ltd. doi:10.1016/j.ecolind.2004.03.005