Friends of the Cawthra Bush
Greater Mississauga Area
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copy, if there are errors, please e-mail me with corrections:
Dear Mr Barber,
The following is a report on our visit to the Cawthra Bush in Mississauga on May 5/98:
The population of the burrowing crayfishes (Fallicambarus fodiens) found in the Cawthra Bush is significant in. that it is not only one of the few populations remaining in the urbanized area around Toronto but also (to my knowledge) the only population recorded to date within a forest ecosystem. Judging by the number of burrows found, the population appears to be large enough to be of significance and may constitute a unique genetic stock for this species. It is important to note that this species has a limited distribution in Canada (it is found only in Southern Ontario-west of Toronto) and it has been recently noted by several experts (see references) that the range of this species is being reduced in southern Ontario and that it should therefore be considered as threatened (due to human activities such as habitat destruction).
I have also examined the water sample from the wetland and found a significant diversity and abundance of aquatic invertebrates (see attached list). The overall abundance of aquatic life as well as the presence of mayflies and the fingernail clams suggests a significant flow as these organisms are usually associated with flowing water (i.e.: streams).
In my opinion the Cawthra Bush represents a very significant pocket of biodiversity within a highly urbanized area. The presence of the rare crayfish, salamanders, molluscs (clams), birdlife such as the Wood duck pair we observed on our visit) and wide variety of native plants surely merits protection. I feel that this site should be left undisturbed and the wetland/stream should be protected from any further drying out by limiting any further waterworks in and around the area.
Your sincerely - Dr. Premek Hamr
List of Aquatic fauna within the Cawthra Bush Wetland
Mayfly larvae (Paraleptophlebia)
Fingernail clams (Pisidiidae)
Hamr, P. 1998. The Conservation Status of Canadian Freshwater Crayfishes. World Wildlife Fund Canada. Toronto, Canada.
Barr, D.W. 1996. The crayfishes (Crustacea, Cambaridae). in Assessment of species diversity in the mixedwood plains ecozone. I.M. Smith Agriculuture Canada. CD ROM / EMAN Home Page. Internet document, http://www.cciw.ca/eman-temp/reports/publications/Mixedwood/crayfish/crayll.htm.
Guiasu R. C., D. W. Barr and D. W. Dunham. 1996. Distribution and status of crayfishes of the genera Cambarus and Fallicambarus (Decapoda: Cambaridae) in Ontario, Canada. Journal of the Crustacean Society 16: 373-383.
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