WASHINGTON'When the River Runs Dry' is a familiar song in Australia. Some rivers in the arid center of the continent flow only after a stiff monsoon season, and smaller tributaries all over the country commonly shrink to puddled potholes and dry river beds during the dry season. But rivers also run dry in more temperate climes. Much of the upper reaches and feeder streams of the great rivers of North America, and even the mighty Amazon, dry out seasonally.
Dry rivers are more than mere desiccated shells of their robustly flowing incarnations, says Australian ecologist Alisha Steward and colleagues. In the May issue of ESA's journal Frontiers in Ecology and the Environment, they contend that dry river ecology is under-researched and under-appreciated.
"I was drawn to dry stream ecology from working on river health monitoring and assessment programs," said Steward, a PhD student at Griffith University in Brisbane, Queensland. "Many potential river monitoring sites turned out to be dry and couldn't be sampled. It was very annoying! It started to get me thinking that 'dry' wasn't necessarily bad or unnatural - some rivers were naturally dry at particular times of the year."
Dry river beds have qualities and inhabitants distinct from their adjacent riversides, as well as from their wet-phase communities, says Steward. They are places of isolation and re-connection: when rivers flow, aquatic animals, plants and microorganisms, organic material, and nutrients flow as well.
Temporary rivers are conduits for biota even when dry, sometimes guiding animals through human-dominated landscapes that lack other continuous habitat. They demand great resilience of their permanent inhabitants, which must be able to survive the swings from immersion to dry land to wet again. Plants, algae, insects, fungi, and even fish have adapted to ride out the dry spells, sometimes seeming to resurrect themselves miraculously from the dust. In the mo
|Contact: Liza Lester|
Ecological Society of America