Fish community composition often varies across ecoregions and hydrogeomorphic types within ecoregions. We evaluated two indices of biotic integrity (IBIs) developed for fish in Great Lakes coastal wetlands dominated (> 50% cover) by Typha (cattail) and Schoenoplectus (formerly Scirpus) (bulrush) vegetation. Thirty-three coastal wetlands dominated by either Typha or Schoenoplectus vegetation were sampled using fyke nets set overnight. These sites were selected to span anthropogenic disturbance gradients based on population density, road density, urban development, point-source pollution, and agricultural inputs (nutrients, sediments), measured using a GIS-based analysis of Great Lakes coastal land use. Sites subject to low levels of anthropogenic influence had high IBI scores. The Typha-specific IBI showed a marginally significant negative correlation with population density and residential development (r = -0.54, p < 0.05; n = 21). The Schoenoplectus-specific IBI negatively correlated most strongly with nutrient and chemical inputs associated with agricultural activity and point-source pollution (r = -0.66 and -0.52, respectively; p < 0.01; n = 30). However, some relationships between IBI and disturbance scores were non-linear and likely exhibit a threshold relationship, particularly for Schoenoplectus dominant sites. Once a certain level of disturbance has been exceeded, a sharp change in fish community's composition and function occurs which is symptomatic of a degraded site. The IBI indices appear to indicate effects of some, but not all classes of anthropogenic disturbance on fish communities. Calibrating these measures against specific stress gradients allows one to interpret the sources of impairment, and thereby use the measures beyond a simple identification of impaired sites.
|Original language||English (US)|
|Number of pages||12|
|Journal||Journal of Great Lakes Research|
|Issue number||SPEC. ISS. 3|
|State||Published - 2007|
Bibliographical noteFunding Information:
We thank the following people for their assistance in field sampling: Katherine Andriash, Jesse Baillargeon, David Branstat, Dan Breneman, Lucas Byrk, Christine Daly, Rebecca Danard, Justin Duncan, Carolyn Foley, Joseph Gathman, Darin Gos-sett, Robert Hell, Jeff Holland, Misun Kang, Marilyn Kullman, Anh Ly, Chris Palvere, Paige Short, Cindy Radix, and Johan Wilkund. We are also grateful to Valerie Brady who provided assistance with data compilation, and Tom Hollenhorst who assisted with GIS analysis. We acknowledge the assistance of Environment Canada, Canadian Wildlife Service, for providing data from Lake Ontario wetlands for use in this project. We thank J.H. Tomal for sharing results of his detailed comparative analysis of the agricultural stress—S-IBI response data set. We are indebted to two anonymous reviewers whose detailed comments markedly improved the manuscript’s clarity. This research was supported by grants from the U.S. EPA’s Science to Achieve Results Estuarine and Great Lakes program through funding to the Great Lakes Environmental Indicators project, U.S. EPA Agreement EPA/R-8286750 and EPA/R-828777. This document has not been subjected to the agency’s required peer and policy review and therefore does not necessarily reflect the views of the agency and no official endorsement should be inferred. This is contribution number 471 from the Center for Water and the Environment, Natural Resources Research Institute, University of Minnesota Duluth.
- Anthropogenic stressors
- Coastal wetland
- Fish IBI
- Great Lakes