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Communication at the NABS Annual meeting, Keystone, 2000
(235) CONSISTANT INCONSISTANCIES:THE CASE AGAINST BIOLOGICAL STANDARDS BASED ON RBP'S IN THE ARID WEST.
T.L. Harris. Metro Wastewater Reclamation District, 6450 York, Denver, Colorado 80229
RBP protocols are based series of metrics. These metrics assess the unaltered aquatic community based on richness, composition, tolerance, or trophic measures. Metrics used for measuring perturbation in much of the United States do not work in disturbed, western streams. Using RBP protocols on Arid West streams provides inconsistent results. In the Arid West all lotic systems are altered. Community richness is often a measure presence of water, not lack of stressors. Community composition of warm-water high desert streams is a reflection of which species can colonize quickest, or survive the heat, rather than a reflection of non-natural perturbations. Tolerant organisms dominate stable communities, intolerant organism can't survive. Trophic measures, provide little insight, when allochthonous production is nearly nonexistant and food source availability is flow dependent. Arid West lotic systems historically were very harsh environments, subject to natural catastrophes. Extreme environments, uncertain flow regimes and poor habitat lead to a depauperate fauna in many streams. In much to the Arid West today, non-natural flow regimes, new habitats with non-native species, now provide for healthy and stable assemblages of tolerant benthic organisms with limited taxonomic diversity. Measurement of these communities health using traditional RBP's could lead to lead to faulty criteria and poorly defined standards.
Presented at 9:30 AM on Thursday, June 1, 2000 in Application of Biocriteria / Standards to Highly Stressed Rivers and Streams
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