Habitat variation at different scales and biotic linkages in lotic systems: consequences for monitorization

Abstract

The Water Framework Directive (WFD) requires the hydromorphological assessment of water bodies, thereby acknowledging the importance of these features in supporting biological quality elements and providing a more complete ecological characterization of surface water bodies. Using a dataset covering mainland Portugal (about 300 sites spread along the different river types) and based on the River Habitat Survey (RHS) field methodology, our aim was to test the spatial variation and the relative role of an array of multi-scale habitat descriptors, in order to: (a) to analyse their geographical variation; (b) to identify the principal variables that express human disturbance; and (c) to assess how three different aquatic communities (invertebrates, fish, and macrophytes) were related to those environmental descriptors. We found that hydromorphological variables described by RHS varied significantly over large geographical scales and were more strongly associated with the principal catchments rather than river type (derived from climatic, geological, and typological factors). RHSderived descriptors were of greater importance in assessing disturbance and were closely related to land use and vegetation on the banks and along the river corridor, despite the considerable geographical variation. Habitat variables were more clearly associated with macrophytes and fish than with the benthic macroinvertebrates, a facet of sampling design, since the scale of biological survey for the former two biological groups approaches the scale used to characterize the surrounding environment. An array of environmental variables, ranging from instream features to bankside and river corridor land use features, was associated with each community, making it difficult to discern any common underlying pattern. Based upon our findings, we propose that hydraulic variables should be included in hydromorphological assessment to improve both the performance of physical indicators and the correspondence with the demands of the WFD.

The links between morphological parameters and benthic invertebrate assemblages, and general implications for hydromorphological river management

“…As observed before, habitat features on local scales might be influenced by regional parameters (typology), and hence, the real effect on aquatic assemblages might be obscured (Richards et al ., ; Cortes et al ., ). The issue of hierarchical interaction of multiscale factors has been of special concern for studies relating natural characteristics and human alterations to river communities, with authors emphasizing the importance of larger scales (Roth et al ., ; Lammert and Allan, ) or of smaller scales (Ormerod et al ., ; Richards et al ., ; Heino et al ., ).…”

“…A large number of studies demonstrate that benthic invertebrate assemblages are influenced by the quality of habitat features (Lammert and Allan, 1999;Rios and Bailey, 2006;Lorion and Kennedy, 2009;Syrovátka et al, 2009) and are also good indicators of morphological degradation (Erba et al, 2006;Feld and Hering, 2007;Larsen and Ormerod, 2010). However, the relationship between benthic invertebrate assemblages and single morphological features included in applied assessment methods was rarely analysed; and most studies considered only RHS features (Erba et al, 2006;Hughes et al, 2008;Cortes et al, 2009;Dunbar et al, 2010). Indices of the SIHM method were used as a stressor gradient in the development of the Slovenian ecological status assessment and classification method using benthic invertebrates (Urbanič, 2014) and showed good explanatory power.…”

Benchmarking habitat quality: observations using River Habitat Survey on near‐natural streams and rivers in northern and western Europe

“…Extending the scope of assessment to the river bank and riparian zone compounds the level of complexity and amplifies the uncertainties in underlying assumptions (Wiens, 2002). With few exceptions (Wilkinson et al, 1998;Hannah et al, 2007;Cortes et al, 2009) these complexities have generally hindered a cross-disciplinary approach. This has been exacerbated by the conflicting requirements for rapid, costeffective data collection needed for national surveillance and reporting purposes (Lazorchak et al, 1998;Kaufmann et al, 1999;Starr and McCandless, 2001;Rankin, 2006) and more detailed specialist understanding of fluvial morphology to inform prescriptive management of individual river reaches Fryirs, 2000, 2005;Newson, 2010).…”

“…Applications of RHS include national reporting on the state of river habitats (Raven et al, 1998b), characterization of river catchments (Newson et al, 1998) and environmental impact assessment (Raven et al, 2000). RHS and derivative versions have also been used to investigate the relationships between habitat features and associated biota, including benthic macroinvertebrates (Erba et al, 2006;Szoszkiewicz et al, 2006;Cortes et al, 2008;Buffagni et al, 2009a,b;Dunbar et al, 2010a,b) river birds (Vaughan et al, 2007), riparian bats (Langton et al, 2010), and various river and riparian plants and animals (Cortes et al, 2009;Hughes et al, 2009). It has also been used to investigate the influence of catchment land use , the impact of flood defence works (Harvey and Wallerstein, 2009) and the effectiveness of riparian restoration (Clews et al, 2010).…”

Predictive Models for Freshwater Biological Assessment: Statistical Approaches, Biological Elements and the Iberian Peninsula Experience: A Review

“…However, the typological and ecoregions approaches have been criticized as ecoregions do not cover the variability among catchments within a region or local characteristics, and stream types may be redundant, fail in explaining variations in aquatic biological communities or inappropriate for all biological elements (e.g., GERRITSEN et al, 2000;LOGAN and FURSE, 2002;WELLS et al, 2002;HAWKINS et al, 2000a;HAWKINS and VINSON, 2000;SÁNCHEZ-MONTOYA et al, 2007;CORTES et al, 2009). A posteriori classifications do not have to deal with these issues as they are biologically based.…”