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Biological Condition Index Development for the Truckee River: Periphyton Assemblage

Prepared By
Clinton J. Davis and Christian H. Fritsen
Desert Research Institute
2215 Raggio Parkway
Reno NV, 89512

Prepared For
Nevada Division of Environmental Protection
February 6, 2006

The objectives of the current activities were to determine if sufficient data was available to derive preliminary periphyton-based metrics that could be used in a periphyton-based indices of ecological condition for the Lower Truckee River, which could in turn be used to derive more comprehensive indices of biological integrity (IBI) based on fish, macroinvertebrates and periphyton populations. Derivation of metrics and indices was made possible through the use of relatively recent (2000 to 2004) seasonal periphyton data that was collected from 11 to 15 locations from California-Nevada border to Pyramid Lake. Although, the levels of taxonomic information from the different data sets were not always comparable, several candidate metrics and indices encompassing information from both the species level and the genera level were identified, calculated and evaluated.

Notable among the metrics most amenable for a Truckee River Periphyton Index were the Siltation Index, Shannon Diversity Index, Eutraphentic Index, Diatom Generic Richness, % Achnanthes minutissima, Chlorophyll a and Ash Free Dry Weight. These metrics covered several aspects of the periphyton community characteristics (richness, composition, tolerance, and habit) that are desired attributes to be accounted for in multimetric indices.

Application of a periphyton-based multimetric index to the mainstem of the Truckee River indicates a general upstream to downstream trend for decreasing ecological condition. However, these results are based on a limited amount of periphyton data and also need to be evaluated in combination with Index’s for fishes and macroinvertebrates in order to gain a more complete picture of the “condition” of the lower Truckee River.

NDEPPeriphytonReport2006.doc594.5 KB