Thursday, May 29, 2008 - 4:30 PM
608

Quantifying long term decreases in the abundance of crayfish populations across central-ontario and investigating potential links to a changing environment

Brie A. Edwards1, Don A. Jackson1, and Keith M. Somers2. (1) Ecology and Evolutionary Biology, University of Toronto, 25 Harbord St., Toronto, ON M5S 3G5, Canada, (2) Dorset Environmental Science Centre, Ontario Ministry of Environment, 1026 Belwood Acres Road, P.O. Box 39, Dorset, ON P0A 1E0, Canada

Previous work on a small number of inland Shield lakes located in the Dorset area has indicated that several crayfish populations are in a significant state of decline. The purpose of this study was to evaluate the spatial extent and severity this trend, on a broad scale across central Ontario’s inland Shield lakes.  Additionally, we were interested in uncovering any environmental changes which may be linked to the observed changes in crayfish abundance.  For instance, it has been recently hypothesized that decreasing lake calcium could be contributing to population declines in related taxa. In order to address these questions, one-hundred lakes were surveyed for crayfish abundance and a number of chemical and environmental parameters.  Historical survey records from the early 1990s were then used to determine whether any significant changes have occurred.  Our results indicate that many crayfish populations have declined significantly, and that the apparent loss of some populations has impacted the distributions of several crayfish species across the study region.  Furthermore, we have found that the decreased availability of calcium in lakes, as well as changes in a number of other environmental characteristics, may be negatively impacting the abundance of these important biological indicators.


Web Page: crayfish, declines, environmental change

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