The importance of physical habitat assessment for evaluating river health

Abstract

Summary 1. Physical habitat is the living space of instream biota; it is a spatially and temporally dynamic entity determined by the interaction of the structural features of the channel and the hydrological regime. 2. This paper reviews the need for physical habitat assessment and the range of physical habitat assessment methods that have been developed in recent years. These methods are needed for assessing improvements made by fishery enhancement and river restoration procedures, and as an intrinsic element of setting environmental flows using instream flow methods. Consequently, the assessment methods must be able to evaluate physical habitat over a range of scales varying from the broad river segment scale (up to hundreds of kilometres) down to the microhabitat level (a few centimetres). 3. Rapid assessment methods involve reconnaissance level surveys (such as the habitat mapping approach) identifying, mapping and measuring key habitat features over long stretches of river in a relatively short space of time. More complex appraisals, such as the Physical Habitat Simulation System (PHABSIM), require more detailed information on microhabitat variations with flow. 4. Key research issues relating to physical habitat evaluation lie in deciding which levels of detail are appropriate for worthwhile yet cost‐effective assessment, and in determining those features that are biologically important and hence can be considered habitat features rather than simple geomorphic features. 5. The development of new technologies particularly relating to survey methods should help improve the speed and level of detail attainable by physical habitat assessments. These methods will provide the necessary information required for the development of the two‐and three‐dimensional physical and hydraulic habitat models. 6. A better understanding of the ways in which the spatial and temporal dynamics of physical habitat determine stream health, and how these elements can be incorporated into assessment methods, remains a key research goal.

Aquatic Habitat Modeling in Running Waters

“…Physical habitat units on the mesoscale (hydromorphological units) are addressed at an intermediate level between microhabitats and reach-scale habitat characteristics and hence are most commonly termed as mesohabitats (Maddock 1999; see also case studies River Ybbs and MEM below). Although, various hydromorphological studies have yet to find consistent numbers of distinctly mesohabitat types for the aquatic environment (e.g., Bain and Knight 1996), variable descriptions of abiotic parameters exist to determine the different habitats on the mesoscale and have served mainly to distinguish between pool, riffle, and run habitats.…”

“…7.4). This was then combined with a historical flow time series to produce a physical habitat time series and hence a physical habitat duration curve (Maddock 1999). …”

“…Fig. 7.4 Concept of a case study on microhabitat scale, which combines abiotic and biotic information (after Maddock 1999). The overall physical habitat simulation shows the integration of (1) hydraulic measurement and modeling and (2) biotic habitat suitability criteria to define the (3) flow versus habitat relationship, which is combined with (4) flow time series to produce (5) habitat time series (example of WUA for brown trout older than 2 years), whereas examples for brown trout life stages habitat use are given in 2a for water depth, in 2b for flow velocity, and in 2c as a CHAID tree method selecting specific fish habitat preferences…”

Domínio Das Ilhas Fluviais: Um Segmento Relativamente Conservado No Degradado Rio Paraíba Do Sul

“…Given the absence of scientific literature, a literature review of the consolidated research of authors such as Power & Dietrich, (2002); Thorp & Casper (2002); Thorp et al (2006) ;Rice, (2001) ;Karr, (1999); Maddock, I. (1999); Ward (1989); Nakamura et al, (1987), Mazoni (2012); Albretch (2012) and Iglesias -Rios (2012), was done in order to understand the functional structure of the Domain of the River Islands and emphasize the effects of confluences along the drainage system.…”

“…Em face da ausência de literatura científica um levantamento bibliográfico extraído através de pesquisas consolidadas de autores tais como Power & Dietrich, (2002); Thorp & Casper (2002); Thorp et al (2006) ;Rice, (2001) ;Karr, (1999); Maddock, I. (1999); Ward (1989);Nakamura et al, (1987), foi realizado e dirigido para determinar o funcionamento estrutural do domínio das Ilhas Fluviais e enfatizar os efeitos das confluências ao longo da rede de drenagem.…”