Natural‐Channel‐Design Restorations That Changed Geomorphology Have Little Effect on Macroinvertebrate Communities in Headwater Streams

Abstract

Stream restorations that increase geomorphic stability can improve habitat quality, which should benefit selected species and local aquatic ecosystems. This assumption is often used to define primary restoration goals; yet, biological responses to restoration are rarely monitored or evaluated methodically. Macroinvertebrate communities were inventoried at 6 study reaches within 5 Catskill Mountain streams between 2002 and 2006 to characterize their responses to natural-channel-design (NCD) restoration. Although bank stability increased significantly at most restored reaches, analyses of variation showed that NCD restorations had no significant effect on 15 of 16 macroinvertebrate community metrics. Multidimensional scaling ordination indicated that communities from all reach types within a stream were much more similar to each other within any given year than they were in the same reaches across years or within any type of reach across streams. These findings indicate that source populations and watershed-scale factors were more important to macroinvertebrate community characteristics than were changes in channel geomorphology associated with NCD restoration. Furthermore, the response of macroinvertebrates to restoration cannot always be used to infer the response of other stream biota to restoration. Thus, a broad perspective is needed to characterize and evaluate the full range of effects that restoration can have on stream ecosystems.

The role of benthic microhabitats in determining the effects of hydromorphological river restoration on macroinvertebrates

“…These findings partly reflect the lack of robust scientific assessments of restoration measures, but even where such assessments have been carried out, changes in invertebrate diversity and community composition have often been minimal (e.g. Louhi et al, 2011;Ernst et al, 2012).…”

Short-Term Impacts of Remeandering Restoration Efforts on Fish Community Structure in a Fourth-Order Stream

“…Further, habitat variables may have influenced other biotic interactions (e.g., filamentous algae blooms, predator-prey interactions, competitive interactions, macroinvertebrate assemblages, and food availability). For example, loss of canopy cover is not uncommon with channel modification restoration practices (this study, [11,36,37]) and can lead to increased in-stream temperatures and primary productivity [11,38]; all factors that could impact fish communities. Extensive filamentous algae blooms were observed in this system in the new channel and downstream areas (to a lesser degree) following restoration [39] and may have influenced fish community composition and structure.…”

Using a Geospatial Model to Relate Fluvial Geomorphology to Macroinvertebrate Habitat in a Prairie River—Part 1: Genus-Level Relationships with Geomorphic Typologies

“…Since geomorphology drives sediment and contaminant transport, geomorphic typology maps could be a valuable tool to strategically locate new monitoring stations. Macroinvertebrates are established as indicators of environmental health, because they often respond more quickly than other groups, like fish, to ecosystem degradation and contaminants [17,18]. Understanding how geomorphology influences macroinvertebrates can be applied further up the food chain as well, as energy and contaminants move bottom up.…”