Channel Vision: Wendy Pyper Outlines a Collaborative Effort to Understand the Rhythm of Life in Lake Eyre Basin

Article excerpt

Changes in the patterns of flow or `hydrology' of a river affect the resident flora and fauna. To understand how hydrology affects ecology, scientists are studying the flow of unregulated rivers in various stages of flood and drought, and the responses of fish, waterbirds, riparian vegetation, microinvertebrates and zooplankton. Information on species richness, abundance, behaviour, health and breeding will then be used to produce models that predict the response of different organisms to different flows. This information is essential for estimating the impacts of hydrological changes on biota, which would occur if the rivers were regulated or exploited for irrigation.

Keywords: Aridflo, biological sampling, fish, river flow, hydrology, biological models, waterbirds, wetlands.

Thirty days is a long time to spend up to your waist in river water. At first, the experience provides welcome relief from the outback sun. But it's not long before the fine suspension of colloidal clay sucks the moisture from your skin.

For scientists studying the bounty of these waters, however, the crocodilian transformation is one they're willing to endure. To ease the ordeal, the Channel country has some of the most spectacular scenery on offer.

`It's a curious combination of great beauty and wilderness, and appalling discomfort,' says freshwater icthyologist, Dr Jim Puckridge.

Puckridge, from Adelaide University's Department of Environmental Biology, is the scientific leader of a project that aims to model the response of flora and fauna to flow patterns in the major rivers that drain the Lake Eyre Basin.

The Environmental flow requirements for Australian arid zone rivers project, also known as ARIDFLO, involves 10 institutions and research organisations, including the South Australian Department for Water Resources, CSIRO, the Australian National University and the Murray Darling Freshwater Research Centre.

Results of the ARIDFLO project will help scientists and natural resource managers to understand the relationships between flow patterns in unregulated arid zone rivers, and the condition of the resident flora and fauna. This understanding will inform community and government debate, and decisions concerning future proposals to regulate the flow of inland rivers, or extract water for irrigation.

`By establishing relationships between the biota and hydrology, we'll be able to predict the impact of water extraction or river regulation,' Puckridge says.

`This research has to be done in the rivers themselves, rather than by extrapolating from what happens in rivers elsewhere, as the Lake Eyre Basin rivers are quite different and the biota is differently adapted.'

Information from the project could also guard against the mistakes that plague other river systems developed without this type of knowledge.

Into the interior

Puckridge has led a band of volunteers, scientists and staff on four expeditions to the arid-zone rivers of South Australia during the past two years.

Along the Neales River, Cooper Creek and the Diamantina River, the team has counted, collected and catalogued fish, invertebrates, zooplankton, waterbirds and riparian vegetation. A Queensland team lead by Vanessa Bailey has repeated this sampling in the upper reaches of the Diamantina River and Cooper Creek.

The field research conducted in April last year coincided with one of the largest floods in the basin since 1990, and a generated a flurry of fish activity. Initially, this was somewhat surprising.

`It has always been assumed that fish breed in summer, but I saw a number of species breeding right through winter as the floods came through,' Puckridge says.

`This demonstrates an unexpected degree of opportunism, but it makes sense. If fish have a chance to breed and produce good offspring, they're not going to wait another 10 years for a summer flood. …