Temporary rivers: linking ecohydrology, ecological quality and reconciliation ecology

Abstract

Temporary streams and rivers, also referred to as intermittent, are defined as waterways that cease to flow at some points in space and time along their course. They are shaped by alternating wet and dry periods over annual and inter-annual cycles, making them one of the most dynamic freshwater ecosystems. These distinctive systems represent a substantial proportion of the total number, length and discharge of the global river network and are expected to become more widespread and face increasing pressures in many regions as a result of human activities and climate change. This collection of papers arose from the Conference on ‘Ecohydrology and Ecological Quality in Temporary Rivers’ held at the University of Evora, Portugal, 12–14 September 2012. The primary objectives of the meeting were to bring together researchers and expertise from a range of temporary ecosystems, from small temporary Mediterranean and Californian streams to intermittent rivers from semi-arid and arid zones. A common thread through the discussions was the assessment of ecological conditions within these dynamic ecosystems. To undertake a ’condition assessment’ is challenging because of the need to differentiate between biotic responses to anthropogenic pressures and natural variability associated with the hydro-climatology and disturbance regime typical of these systems, that is, drought, drying and flooding. The management of degraded intermittent streams and rivers presents many new challenges, not least how to reconcile ecological and societal goals for emerging ‘novel’ ecosystems. Reconciliation ecology presents a realistic way of managing novel ecosystems given their value and desirable ecological services to society, rather than trying to restore to an original ecological state that may not be sustainable or economically possible.