The presence of trees and other vegetation encourages rain to filter into the soil before gradually flowing downhill to streams and rivers. Replacing soil and plants by hard surfaces (such as roofs and roads) encourages rain runoff to run much more rapidly to the nearest stream or river, especially if it travels through an impermeable stormwater drain or pipe. In turn, this promotes bank and channel erosion and reduces flow in the channel between storms. It also carries a wide range of pollutants into waterways, including grease and oil from roads, litter, and toxic metals from many sources, including metal roofing (zinc), tires (zinc and cadmium) and wear of other car parts (chromium, nickel and copper). This suite of noxious impacts has been aptly characterised as “urban stream syndrome” (Walsh et al. 2005).
The platypus is correctly described as being sensitive to urban development (Serena and Pettigrove 2005). Furthermore, based on sophisticated modelling, adult females disappear more quickly from urban water courses than males, presumably because a female platypus’s home range must be productive enough to support both her and her develping offspring (Martin et al. 2014).
If you live in an urban area, you can help to reduce impacts of urban development on your local waterways in the following ways:
- Install one or more rain tanks to collect water from your house and/or shed roof.
- If possible, use permeable materials (such as loose gravel or porous paving) when developing low maintenance surfaces in your garden.
- Ensure that any areas of bare soil in your garden are covered by gravel or organic mulches so they don’t erode.
- If possible, encourage rain that falls on concrete or hard paving to flow towards a garden bed or lawn (rather than to the street or a concrete drain).
Photos: APC
LITERATURE CITED
Coleman RA, En Chee Y, Bond NR, Weeks A, Griffiths J, Serena M, Williams GA and Walsh CJ (2022) Understanding and managing the interactive impacts of growth in urban land use and climate change on freshwater biota: a case study using the platypus (Ornithorhynchus anatinus). Global Change Biology 28, 1287-1300.
Martin EH, Walsh CJ, Serena M and Webb JA (2014) Urban stormwater runoff limits distribution of platypus. Austral Ecology 39, 337-345.
Serena M and Pettigrove V (2005) Relationship of sediment toxicants and water quality to the distribution of platypus population in urban streams. Freshwater Science 24, 679-689.
Walsh CJ, Roy AH, Feminella JW, Cottingham PD, Groffman PM and Morgan PR (2005) The urban stream syndrome: current knowledge and the search for a cure. Freshwater Science 24, 706-723.