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Title: River Flow Indexing using benthic macroinvertebrates
Author: Environment Agency South West Region
Document Type: Monograph
Changing weather patterns, possibly linked to global climate change, are currently of major concern, not least because alterations in hydrological regime could lead to significant and sustained shifts in riverine ecology (Arnell. 1996). In the United Kingdom, periods of drought are becoming more frequent (Mawdsley et al. 1994) and general declines in precipitation, coupled with unremitting demands on surface and groundwater resources, are resulting in diminished or disappearing river flows. A number of historic studies have focused on general ecological change associated with drought (eg. Ladle and Bass, 1981) and further work (Extence, 1981; Wright, 1992; Bickerton et al, 1993; Wood and Petts, 1994; Castella et al, 1995) has specifically examined the impact of low flows on lotic macroinvertebrate communities. Many freshwater invertebrates have precise requirements for particular current velocities and flow ranges (Chutter, 1969; Hynes. 1970; Statzner et al., 1988; Brooks, 1990), and certain taxa may, therefore, be ideal indicators of hydrological regime. As well as qualitative responses to flow changes, site specific studies also show that most taxa associated with low flow tend to increase in abundance as flows decline, whereas most species associated with moderate to rapid flows exhibit the opposite response (Moth Iversen et a l, 1978; Extence, 1981; Cowx et al, 1984; Wright and Berrie, 1987; Boulton and Lake, 1992; Wright. 1992; Miller and Golladay, 1996). Alterations in community structure may occur as a direct consequence of varying flow patterns, or indirectly through associated habitat change (Petts and Maddock, 1994; Petts and Bickerton, 1997a). In order to critically examine the effectiveness of the proposed flow index, results from five geographically and geologically distinct rivers in England are presented in detail. Data from a number of other rivers are additionally provided in summary form, and in these cases, study site details are more appropriately placed in the results section. Chalk rivers are now recognised as a key biodiversity habitat in Europe (HMSO, 1995a and 1995b) and most European rivers of this type are found in England, including the Lark and Waithe Beck (Anglian region) and the Kennet (Thames region).
Publisher: Environment Agency
Publication Date: [after 1996]
Publication Place: Lincoln
Subject Keywords: RiversRiver levelEcological factorsClimate changeFlow rateMacroinvertebratesChalk streamsMethodology
Geographic Keywords: England
Extent: 60
Total file downloads: 283

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