Friends of the Cawthra Bush
Greater Mississauga Area
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Urban Forest Management Advisory Committee (UFMAC)
RE: City of Mississauga management plans for the Cawthra Bush
March 27, 1998
Dear Ms. Trainor:
Wetlands are dynamic and productive ecosystems that provide habitat and hydrological functions, prevent erosion and are a filter for water pollutants. Amphibians may be used as indicators of environmental change within these systems, and their presence often signifies the quality of water and surrounding habitat. Conservation of urban biodiversity is particularly important if we are to preserve local habitat and natural corridors, that link us with surrounding natural areas. Natural areas within urban settings create connections that ultimately build empathy and concern for natural areas. Community action to preserve local ecosystem diversity will ultimately contribute to broader ecological processes that contribute to the quality of life, particularly in urban areas..
Wetlands are one of the most diverse and productive ecosystems on Earth. In southern Ontario alone, research suggests that over 75% of the presettlement wetlands have been lost due to drainage, filling or habitat alterations. To date, 80-90% of Canada's urban wetlands have been destroyed. This is a huge loss of habitat considering Canada has 24% of all the wetlands on the Earth. In recent years a decline in amphibian populations has highlighted the need to protect amphibians and the wetlands on which they depend.
Wetlands are areas of land covered with shallow water or have water at or near the surface, for all or part of the year. Wetlands are important for several reasons. They represent only a part of our land base but they shelter a great number of animal and plant species. Many species also use wetlands to breed and reproduce. Wetlands moderate water flow, by absorbing much of the surface water runoff from the land, and then slowly releasing it. Wetlands can reduce peak flows to streams and maintain water levels during dry periods. Thus wetlands help to reduce flooding and to sustain water flow during dry spells. Wetlands also play an important role in water quality and prevent erosion, by trapping sediments, and absorbing excess nutrients and heavy metals. Wetlands add a diversity of species to our communities by providing refuges for wetland wild life and when linked, create natural corridors.
Amphibian species such as salamanders, frogs and toads are an important component of wetland biodiversity. Water is essential to the survival of amphibians. They have aquatic larva that feed on vegetation and decaying organic matter and a terrestrial adult stage that lives on land and in water, and eats insects. Anything that affects the water quality of their aquatic or terrestrial environment, affects amphibians. Amphibians also serve as prey or predators in the ecosystem, and are an important part of the food chain. Due to their dual lives on land and in the water, amphibians are a good indicator species of water quality and a healthy wetland. Any changes in their abundance or distribution indicate changes in the habitats which support them.
Amphibians do not drink, but absorb water and oxygen through their thin skin. To avoid exposure to the drying effects of the sun, they shelter in cool moist habitats under rocks, logs, leaves, mosses and ferns. Adult amphibians may live on land, but must return to the water to breed and in some cases to hibernate. Salamanders mate once per year, they migrate overland to ponds and vernal pools where the males and females court, mate and produce offspring. Vernal pools form in the spring when rain pools in a low area, and provide breeding grounds for migrating salamanders.
The Jefferson salamander is a large 12-18 cm salamander with greyish-black with bluish-white flecks on the legs and lower sides of body and a light grey belly. The species range includes Peel, Halton, and Waterloo counties. Jefferson salamanders breed in temporary and permanent pools, and flooded ditches in wooded areas. These salamanders prefer forest ponds in undisturbed welldrained woodlands, spending their summer underground in tunnels beneath stumps and rocks, emerging to feed in wet weather. During hibernation Jefferson salamanders move further underground in the same burrows under logs or leaf litter. The presence of this species, among others, is particularly noteworthy and is indicative of the quality of the urban habitat.
Sincerely - Heather Passmore, Adopt-a-Pond Coordinator Toronto Zoo.
Tel. (416) 392-5900 Fax (416)
392-5934 - www.torontozoo.com
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