Future of Great Plains fish species in doubt


The future of many of the fish species resident in the streams of the American western Great Plains region is under threat due to ground water abstraction.

The new research, published in the journal Ecohydrology, warns that suitable habitat for the fish species native to the region is being severely degraded and reduced by the pumping of ground water from the High Plains aquifer, leaving their long term survival chances looking 'bleak'.

The problem stems from the geology of the region which means the aquifers are not replenished seasonally by rain and instead were filled by melting glaciers at the end of the last ice age. This means the water is a finite resource, and one that won't be replaced until the area goes through the next ice age - something unlikely to happen in the next few years.

A research team from Oregon State University spent three years studying the Arikaree River in eastern Colorado, mapping refuge pools left during dry periods and the connectivity between these. The results were then compared with historical data on the area.

Their conclusions were shocking. Even in the most optimistic circumstances in the next 35 years only 57% of the current refuge pools would still be in existence and almost all of these would be contained within an isolated mile long stretch of the river.

This lack of year round habitat could have devastating consequences on the ability of native fish such as Brassy minnows (Hybognathus hankinsoni) and Orange-throat darters (Etheostoma spectabile) to survive dry periods by impeding their life cycles and limiting their ability to recolonise.

The scientists also say that other dry-land streams in the region face the same fate and the damage caused by continued abstraction has implications that will impact the entire Great Plains ecosystem, not just fish. Almost all the water abstracted is used for agriculture.

For more information see the paper; Falke, J. A., Fausch, K. D., Magelky, R., Aldred, A., Durnford, D. S., Riley, L. K. and Oad, R. (2011), The role of groundwater pumping and drought in shaping ecological futures for stream fishes in a dryland river basin of the western Great Plains, USA. Ecohydrology, 4: 682ñ697. doi: 10.1002/eco.158

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