Spatial Analysis of the Impacts of Urbanisation on the Health of Ephemeral Streams in Southeast Queensland

Abstract

Aquatic ecosystems are vulnerable to threats from human activity. Numerous studies have shown that urban freshwater stream ecosystems are especially vulnerable to the intensity and complexity of stream health stressors associated with activities in the surrounding urban landscape. Scientists, government organisations and local volunteer groups are well aware of the deteriorating health of urban streams and are working towards understanding and managing the sources of stress on stream health. Improving the health of urban streams has the potential to provide local benefits such as biodiversity protection, enhanced ecosystem health, water purification, access to green space, scenic amenity and improved land values. While several important stressors have been identified in the Urban Stream Syndrome (elevated sediments, nutrients and contaminants, increased hydrologic flashiness and altered riparian and biotic assemblages) further research is required on the most important stressors and the mechanisms by which they impact stream health, especially in systems within dry climates where urban streams experience low flow conditions and flashy natural hydrology. Catchment-scale impervious surface has been identified in previous studies as a major driver of altered urban stream hydrology leading to degraded stream health. However, especially in drier climates, other aspects such as water quality and ecological processes associated with longitudinal and lateral connectivity have been identified as potentially more important stressors on urban stream health.