Otago University Researchers Lauded for World Leading Freshwater Study

Otago University students and staff have set up a world leading system for testing freshwater in a "real" rather than laboratory situation.

The ExStream system set up at the Kauru River in Otago. Via: Stuff.nz

On Otago's Kauru River, the researchers can test for a variety of indicators to see how freshwater ecosystems respond to multiple agricultural stresses, including high and low flows, the presence of pesticides, nitrogen, and phosphate.

They have also designed it to study what happens to the water under a climate warming scenario - a world first.

The researchers won the "stories" section of the New Zealand River Awards for their ExStream project, which has now been established in Germany, Ireland, China and Japan.

Researchers know that agriculture and forestry lead to nutrient enrichment from run-off, with sedimentation smothering stream beds.

They also know that water abstracted for irrigation results in changed water quantity. As stresses happen simultaneously, it's difficult to work out which one causes the effects and – importantly – how to prioritise mitigation.

Kauru River was chosen to conduct field work because its water quality was relatively good. This project wasn't about improving Kauru River water quality specifically, but was about how to conduct the research needed to find out the answers to real problems; and applying findings to rivers elsewhere.

The ExStream is open to the air and exposed to the same weather and light conditions that the river experiences, which means a much more realistic experimental set-up than one in a laboratory. Substrates in the mesocosms reflect natural substrates seen in rivers.

Stream variables can be manipulated, including water flow, grades and amounts of fine sediment, incoming water temperature, nutrients plus commonly used agricultural chemicals. The technology allows measurement of these impacts on algal and invertebrate communities and ecosystem function, such as leaf decomposition.

Read full article: Stuff.nz

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Taxonomy

• Ecosystem Management
• River Studies
• Ecosystem Management
• Freshwater
• River Restoration
• River Engineering
• Pollution