New method for retrospective bioindication of stream drying up based on the analysis of taxonomical and functional composition of aquatic macroinvertebrates
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| Year of publication | 2016 |
| Type | Conference abstract |
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| Description | Flow abruption or complete drying up of small streams (up to 4th Strahler order) has become more frequent in the temperate zone in the last decades as a consequence of climate change together with human alterations of hydrological regime. The novel method developed for Czech streams during the BIODROUGHT project (biodrought.eu) enables retrospective bioindication of dry episodes in stream history using benthic macroinvertebrates. The method comprises the calculation of biological metrics related to drought duration and the spatial extent of affected stretch to evaluate the magnitude of stream impairment by drought during the preceding vegetation season. The dry episode is defined as the abruption of flow continuity and three stream types were distinguished: permanent,vulnerable and intermittent. Multihabitat kick samples were taken from 20 streams (arranged in 10 pairs consisting from permanent and intermittent stream) in spring and autumn seasons (2012-14). Based on literature review, 35 species traits related to species resistance or resilience to drought were chosen. More than 350 indicators of stream permanency or intermittency were identified using ISA. Representation of drought sensitive groups (e.g. aquatic insects like EPT taxa) and changes in the taxonomical composition of the whole community were analysed. Season specific approach was used in the study (spring and autumn data were analysed separately) and LDA was employed to select the best combination of metrics to distinguish between the three stream types. Based on the LDA results, we defined discriminant function describing the gradient from permanent to intermittent streams, which can be used to classify each sample to one of the three distinguished stream types with defined probability. The developed method is suitable for the recognition of drought impact in stream history but also for the evaluation of measures aimed at the reduction of negative impacts of drought on water courses. |