Document: MAT-3-75-16

The potential effects of floodplain restoration on habitat availability and ecosystem structure and function in the upper Colorado River basin.

TOWNSEND, M.J.*, T.A.CROWL, J.L.GOURLEY and R.H.PHILLIPS

Utah State University, Logan, UT 84322 ¹

Abstract:
Inundated floodplains adjacent to large rivers are potentially important habitats for many species of fish, including the endangered razorback sucker (Xyrauchen texanus), and may be critical components of overall riverine structure and function. Availability of these kinds of habitats has been severely reduced in the Colorado River basin by artificial levees, irrigation requirements, and dam operations. In 1996, we began a large scale floodplain restoration program on the Green River (Utah, USA). The project is designed to restore floodplain habitat availability as well as the myriad of ecosystem processes associated with such habitats such as increasing primary and secondary production and the flux of nutrients and carbon into the riverine environment. Our results from the past three years suggest that enhanced flood plains do represent important sources of zooplankton to the main channel and ultimately, to the fish that inhabit the riverine environment. Most importantly, floodplains represent an important source-sink dynamic with regard to detrital processing and the detrital food web. Many of the restored sites actually represent a net loss of detrital material and dissolved nutrients from the riverine system; however, these flood plains are sources of organic carbon to the river in the form of zooplankton and dissolved organic carbon, both derived from in-flood plain phytoplankton production. This behavior dramatically changes the structure and dominant pathway of energy flow in the river food web.

Keywords: detrital processing, floodplains, flood-pulse, large-river ecology

This abstract is being presented at: 10:30 AM in session:
RIPARIAN ECOLOGY