Do indices of biological condition really work in measuring aquatic health?
Ann Arbor, MI — With increasing levels of human disturbance in the Great Lakes basin, it's not too surprising that our wetlands are experiencing strong effects of that disturbance. Measuring the health of a wetland is important if we are to understand the effects of various types of human disturbances and develop ways of repairing some of the negative effects.
One of the most common ways of measuring health of a waterbody is to develop an index based on measurements of the types of fishes expected to be found in undisturbed habitats, and then test those indices against various human related disturbances to see how fish communities respond to different types of stress.
Using fish data from 36 sites that represented a broad range of disturbances across the Great Lakes, researchers from the Great Lakes Environmental Indicators (GLEI) project tested how well two indices indicated different types of human disturbance. What stood out was the finding that a threshold rather than a straight line relationship best explains how fish communities respond to human related stressors.
"Threshold values can provide guidance to managers regarding the limits of pollution in a habitat, at which major and perhaps irreversible changes can be expected in the fish community composition," says Yakuta Bhagat and colleagues from the University of Windsor, Ontario and the Annis Water Resources Institute, Michigan.
The indices tested were found to be good indicators of stress related to population pressure and agricultural activities, but were insensitive to other types of disturbances such as shoreline modification, atmospheric deposition and land cover. This implies that the indices do work, but only for certain classes of human activity. These results show the importance of carefully cross-checking new indices across a full spectrum of disturbances to establish their applicability and sensitivity.
Original Publication Information
Results of this study "Testing a Fish Index of Biotic Integrity for Responses to Different Stressors in Great Lakes Coastal Wetlands," are reported by Yakuta Bhagat, Jan J.H. Ciborowski, Lucinda B. Johnson, Donald G. Uzarski, Thomas M. Burton, Steven T.A. Timmermans and Matthew J. Cooper in the latest issue (Volume 33, SI3, pp. 224-235) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2007.
Contacts
For more information about the study, contact Yakuta Bhagat, Trent University, Peterborough, Ontario, Canada K9J 7B8; yakutabhagat@trentu.ca, (705) 748-1011 ext. 7341.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; editor@iaglr.org; (608) 692-1076.
Links
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.
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