Controlling for hydrologic connectivity to assess the importance of catchment- and reach-scale factors on macroinvertebrate community structure

• Published in: Hydrobiologia Vol. 763; no. 1; pp. 285 - 299
• Main Authors: Hale, Alison N., Noble, Grace, Piper, Kaitlin, Garmire, Keith, Tonsor, Stephen J.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.01.2016; Springer Nature B.V
• Subjects: Aquatic ecosystems; Biodiversity; Biomedical and Life Sciences; Catchment scale; Catchments; Community ecology; Community structure; Creeks & streams; Ecology; Freshwater & Marine Ecology; Habitat fragmentation; Habitats; Land use; Life Sciences; Macroinvertebrates; Natural resource management; Pasture; Primary Research Paper; Zoology; USA, Pennsylvania; Spatial autocorrelation; Hydrologic connectivity; Benthic macroinvertebrates; Total Biological Score; Land use; Pennsylvania
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-015-2385-z

Understanding landscape influences on stream ecosystems is a challenging task due to the spatial complexity and connectedness of stream networks. Here, we control for longitudinal connectivity to provide a robust test of the relative importance of reach- and catchment-scale factors in determining macroinvertebrate community structure in southwestern Pennsylvania streams. We determined that sites separated by ≤510 m along the stream network had significantly correlated macroinvertebrate community scores. After controlling for this spatial autocorrelation, a partial least squares regression identified two factors that together accounted for 32% of the variation in community scores. In this model, two reach-scale factors—habitat assessment score and stream pH—were the most important factors for predicting a stream’s macroinvertebrate community score. However, landscape diversity was also important. Landscape diversity is a catchment-scale factor that was highly correlated with percent pasture/hay and measures of habitat fragmentation. Our results provide support for the idea that stream communities in undisturbed areas are heavily influenced by reach-scale characteristics. Furthermore, our results indicate that Pennsylvania natural resource managers should consider habitat score and stream pH after accounting for spatial autocorrelation when identifying restoration targets for impacted streams.