Abiotic stream types and species assemblages: Is there any simple linkage? Czech streams and benthic macroinvertebrates as an example
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| Year of publication | 2004 |
| Type | Conference abstract |
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| Description | Ecological status assessment of water bodies according to the European Water Framework Directive (WFD) is generally based on the comparison of a reference and observed status. There are two basic approaches to define the reference conditions for a particular water body: a site-specific and a type-specific. For the latter, required by the Directive, it is necessary to create a typology of water bodies. The Directive offers two ways (system A, system B) of their inherence based on abiotic descriptors. Within the assessment based on biological elements, various metrics derived from the species assemblage composition are used. The type-specific approach is associated with a multimetric system, i.e. sets of metrics for selected stressors and specific water body types (AQEM consortium 2002). The site-specific approach, which is independent on typology and deals with abiotic conditions (descriptors) of a particular site or stretch, is associated with predictive models like the British RIVPACS (WRIGHT et al. 1993) or analogous the Czech PERLA (KOKEŠ et al. 2001). More or less detailed knowledge of biotic and abiotic conditions of pristine or near natural sites is necessary for both approaches. Due to the fact that the metrics are generally derived from taxonomic composition of the species assemblages, a correspondence between types and these assemblages is essential for the truthfulness of the type-specific approach. Therefore, the selection of abiotic descriptors should be done very carefully. The correspondence among species assemblages of reference sites and abiotic types was tested on Czech streams and benthic macroinvertebrates. |
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