PARENT SESSION
Contributed Oral Session 73: Aquatic Ecology: Management of Streams and Lakes
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 513 A, Level 5, Palais des congrès de Montréal
Testing differences in the biological community of streams using watershed classifications.
Pyne, Matthew*,1, Rader, Russell1, Winters, David2, 1 Brigham Young University, Provo, UT, USA2 USDA Forest Service, Golden, CO, USA
ABSTRACT- The attributes of the physical environment that influence a species life history can vary depending on scale. Large-scale characteristics of a watershed, such as the drainage density, can influence site-specific characteristics, such as discharge, which in-turn can affect community composition (e.g. invertebrate richness and relative abundance). Region 2 of the USDA Forest Service has developed a technique to cluster watersheds in a region based on large-scale physical characteristics, termed ecological drivers, which they believe should have a significant impact of the flora and fauna of stream ecosystems. We collected algal biomass, macroinvertebrate richness and total macroinvertebrate community dry weight biomass, and brook trout growth rates in sixteen watersheds in the Big Horn Mountains of Wyoming to test the ability of this Forest Service watershed classification scheme to predict variation in the biological properties of streams. These biological data were used to compare three watershed classification models: 1) the FS model, 2) an alternative model created from watershed characteristics obtained from digital elevation models (e.g. watershed vertical relief, maximum elevation, drainage density, etc.), and 3) a null model based on the distance between watersheds. The biological data was also compared to site-specific characteristics (e.g. pH, total dissolved solids, reach type, etc.). Preliminary ANOVA and regression analysis of the algal biomass and first year otolith growth data indicated that the digital elevation and forest service models were statistically significant (p < 0.05) explanatory variables, but both models had low r-squared values (< 5%), and only accounted for a small amount of the variation in these data.
Key words: watersheds, geomorphology, stream community, large-scale