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Tuesday, May 27, 2008
318
Seasonal effects on periphyton and water chemistry in an arid-land river
Nathan Daves-Brody, Rebecca J. Bixby, and Ayesha S. Burdett. Department of Biology, Museum of Southwest Biology, University of New Mexico, MSC-3 2020, 1 University of New Mexico, Albuquerque, NM 87131
The Rio Grande is a heavily managed arid-land river. In general, the system is nutrient-limited although anthropogenic sources (e.g., wastewater effluent) contribute inputs. Seasonal changes in water flows are concomitant with changes in water temperature, turbidity and light availability. These factors can influence periphyton biomass and community composition. Additionally, seasonal variability often results in prolonged drying events with habitat maintained in isolated pools. We sampled quarterly at sites along the middle Rio Grande in central New Mexico. These sites were selected based on location relative to wastewater treatment effluent discharge and influences of irrigation returns. We analyzed water chemistry and periphyton parameters including chlorophyll a and species assemblages. Nutrients and specific conductivity change seasonally and vary with river velocity. Results suggest that turbidity and light limitation are major factors in limiting periphyton biomass. Seasonally, diatom communities were dominated by alkaline taxa (e.g., Cocconeis placentula, Epithemia sorex), which was surprising, given pH levels ~8.0-8.5. Understanding seasonal dynamics of periphyton, which serves as a food source for higher trophic levels, is important given the variability of arid-land rivers and paucity of periphyton studies in this region.
Web Page: turbidity, nutrients, irrigation
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See more of The Nabs 56th Annual Meeting (25-28 May, 2008)
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See more of The Nabs 56th Annual Meeting (25-28 May, 2008)