The effect of an interstate highway on macroinvertebrate production in headwater streams

The effects of the Maine Turnpike (> 50 million vehicles y(-1)) on macroinvertebrate assemblage structure, macroinvertebrate production, and stored and suspended organic matter were examined in five 1(st) and 2(nd) order low-gradient streams in southern Maine. Streams were sampled upstream and downstream of roadway crossings. Differences in habitat structure, water and sediment chemistry, and biotic communities were evident among streams. However, the variability in these attributes among streams was greater than within-stream differences attributable to the presence of the roadway. Total secondary production showed little sensitivity to stresses related to the roadway, but was related to water chemistry, substrate particle size, discharge, and stored organic matter. Habitat characteristics, such as the type of stored organic matter, related to high production differed between streams with coarse versus fine substrates. Production in the study streams was comparable to estimates from other small streams on the coastal plain of the eastern United States (3.5-15.3 gAFDM m(-2) y(-1)). This study demonstrates that structure and function of headwater stream ecosystems may be maintained in the presence of a major roadway.