Ecosystem response to changes in water level of Lake Ontario marshes: lessons from the restoration of Cootes Paradise Marsh

  • Published source details Chow-Fraser P. (2005) Ecosystem response to changes in water level of Lake Ontario marshes: lessons from the restoration of Cootes Paradise Marsh. Hydrobiologia, 539, 189-204.


This study is summarised as evidence for the following.

Action Category

Exclude wild vertebrates: freshwater marshes

Action Link
Marsh and Swamp Conservation
  1. Exclude wild vertebrates: freshwater marshes

    A before-and-after study in 1934–1999 of a freshwater marsh in Ontario, Canada (Chow-Fraser 2005) found that excluding common carp Cyprinus carpio had no significant effect on the area covered by emergent vegetation. Two years after carp exclusion, the area covered by emergent vegetation (19% of the marsh) did not significantly differ from expected coverage given the water level at the time (23–28%). Methods: From spring 1997, a barrier system was used to prevent large carp (>40 cm long) from migrating into the marsh from the adjacent lake. The area of emergent vegetation across the marsh before (1934–1990) and after (1999) carp exclusion was obtained from previously published data (based on aerial photographs or field surveys). Carp had been introduced in 1908. The relationship between emergent vegetation coverage and water level before exclusion was used to determine the expected coverage based on the water level after exclusion. Note that other restoration interventions had been carried out since 1992 (sewage management, watershed land management, planting vegetation; see Smith et al. 2001).

    Additional reference: Smith T., Lundholm J. & Simser L. (2001) Wetland vegetation monitoring in Cootes Paradise: measuring the response to a fishway/carp barrier. Ecological Restoration, 19, 145–154.

    (Summarised by: Nigel Taylor)

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