Comparability of Benthic Macroinvertebrate Sampling Methods in Montana Streams

There are several benthic macroinvertebrate sampling techniques currently being used by the Montana Department of Environmental Quality (DEQ) that evaluate instream water resource quality. A traveling kick or a jab with a D-frame net collects most samples. DEQ monitors a smaller proportion of sites using Hess Samplers. Also used in the state are the sampling methods of the U.S. EPA Environmental Monitoring and Assessment Program (EMAP) and Regional Environmental Monitoring and Assessment Program (REMAP). Both EMAP and REMAP use a D-frame net, distributing sampling effort throughout the target reach along a series of transects. The purpose of this study is to evaluate the effects of these four different sampling techniques on the samples gathered, in particular, on taxonomic diversity and metric values. This evaluation will help DEQ accomplish its ultimate goal: to implement consistent statewide sampling protocols. We developed a suite of both quantitative and qualitative performance characteristics (precision, accuracy, bias) for each of the methods, and directly compared them among the protocols. The level of comparability among methods was characterized and the acceptability of each method for use by Montana DEQ was determined.