Interactions between macroinvertebrate taxa and complex environmental gradients influencing abundance and distribution in the Umatilla River, Northeastern Oregon

Abstract

Non-parametric multiplicative regression was used to develop regression models for six macroinvertebrate genera present in the Umatilla River in northeastern Oregon. For all taxa, elevation, turbidity, and conductivity were identified as predictors. They described between 25.5% and 63.4% of the variation in the abundance of the six taxa. Sensitivity analysis of the parameters showed the relative importance of the model parameters as predictors of abundance, with conductivity having a broader range of sensitivity values than either elevation or turbidity. Daily average temperature, percentage of algal cover, depth, and width were also shown to be possible predictors of taxa abundance. As all the variables examined in this study are potentially impacted by non-target effects of agriculture in rivers, these results indicated that agriculture disturbance in the adjacent landscape affects the abundance and distribution of benthic indicator taxa.