Rapid Geomorphic and Habitat Stream Assessment Techniques Inform Restoration Differently Based on Levels of Stream Disturbance

Abstract

Visual‐based rapid assessment techniques provide an efficient method for characterizing the restoration potential of streams, with many focusing on channel stability and instream habitat features. Few studies, however, have compared these techniques to see if they result in differing restoration priorities. Three rapid assessment techniques were contrasted at three wild trout streams in western New York with different amounts of channel disturbance. Two methods focused only on geomorphic stability, whereas the third addressed physical habitat condition. Habitat assessment scores were not correlated with scores for either geomorphic assessment method and they varied more between channels with different degrees of disturbance. A model based on dynamic equilibrium concepts best explains the variation among the streams and techniques because it accounts for a stream's capacity to maintain ecological integrity despite some inherent instability. Geomorphic indices can serve as effective proxies for biological indices in highly disturbed systems. Yet, this may not be the case in less disturbed systems, where geomorphic indices cannot differentiate channel adjustments that impact biota from those that do not. Dynamically stable streams can include both stable and unstable reaches locally as characterized by geomorphic methods and translating these results into restoration priorities may not be appropriate if interpretations are limited to the reach scale.

Aplicação e análise comparativa de três protocolos de avaliação rápida para caracterização da paisagem fluvial

“…O uso dos protocolos oferece uma visão geral da qualidade ambiental, que pode ser utilizada pelos gestores de recursos hídricos como instrumentos complementares (Rodrigues e Castro, 2008). Além disso, também são empregados: como instrumentos de educação ambiental (Guimarães et al, 2012); na formação profissional (Callisto et al, 2002); na caracterização hidromorfológica na escala de trecho de rio (Fernández et al, 2011); no monitoramento ambiental (Pardo et al, 2002) e na perspectiva de recuperação de rios (Habberfield et al, 2014). Isso ilustra a gama de aplicação e a utilidade da ferramenta.…”

“…O resultado do uso dos protocolos pode fazer parte dos estudos ecológicos dos cursos d'água (Barbour et al, 1999) e de estratégias de monitoramento (Rodrigues e Castro, 2008), bem como estar presente no contexto de recuperação de rios (Habberfield et al, 2014), pois a aplicação dos mesmos é bastante efetiva no conhecimento do sistema fluvial de modo amplo. Nesse sentido, os protocolos se tornam instrumentos úteis, de baixo custo e relativa facilidade de aplicação, sendo tais aspectos também amplamente reconhecidos (Barbour et al, 1999;Callisto et al, 2001;Rodrigues e Castro, 2008).…”

Metabolic Variance: A Metric to Detect Shifts in Stream Ecosystem Function as a Result of Stream Restoration

“…The instability here is not necessarily due to a change in discharge, but rather related to the sediment load and sediment size, as the left bank is made of highly erodible back‐fill (Habberfield et al. ). In this case, calculating only the P / R ratio could be misleading as to the underlying ecosystem function (Figure ).…”

“…Riparian conditions were similar in all reaches except for the left bank of Reach 1. Additional details on each reach can be found in Habberfield et al (2014). For all four reaches, DO and temperature were monitored continuously through multiple diurnal cycles (see Table 1 for number of days observed in each reach) within a multiple week period in the summer months June and July over two seasons (2011 and 2012).…”

“…The significant difference in metabolic function in Reach 1 compared to the other remaining reaches suggests that stream metabolism is sensitive to instability at the reach level. This might be expected, as stream stability is often expressed as bank stability/ instability (per Habberfield et al 2014), influencing the condition of riparian cover and W/D relationships of the stream, and thus potentially affecting light availability to stream reach benthos. The level of variability in the recently restored reach (Reach 4) also suggests that there is a period of transition where instream conditions need to be established and stability restored.…”