No country for old perennial streams alias Czech drying through the looking glass
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| Year of publication | 2018 |
| Type | Conference abstract |
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| Description | Intermittent streams have been overlooked by limnologists for decades although rising water scarcity induced by climate change accompanied by anthropogenic alterations of catchments, drying impacts on stream biota are now studied more extensively. Supra-seasonal drought in last 5 years strongly altered flow regime in many Czech streams. Thus, in some south-eastern regions it is not easy to find small flowing stream after summer heat waves, if it is not fed by wastewater treatment plant. Some stream channels become a terrestrial ecosystem for prevalent part of a year and they are colonised by terrestrial biota, however specific part of aquatic community is able to survive in moist riverbed sediment. Resistance of such macroinvertebrates is related to humidity but also to substrate structure (permeability), channel morphology and overall diversity of habitats. By way of contrast, the dry riverbed is new and relatively unique bare habitat for terrestrial invertebrates, which is often missing in many Czech heavily modified rivers. Furthermore, dry channels can be attractive for terrestrial vertebrates either immediately after dry phase onset as source of food or later as easily passable migratory corridor. Residual pools, especially those fed by groundwater, can be an important refuge (especially for fish) and may host specific aquatic macroinvertebrate community, which differs remarkably from communities occurring during the flow phase. Autumn (in last years even winter) flow resumption is delayed to cold part of season when recolonization runs slowly. Thus, repeated extensive stream drying gradually selects the most drying resistant and resilient taxa, which leads towards the whole community transformation. These processes can be further accelerated by impact of anthropogenic pollution associated with hydromorphological degradation and land-use alteration. For ecologist it is very challenging to study these phenomena and suggest suitable catchment management which enables long term survival of this specific biodiversity. Research was supported by INTER-COST (LTC17017) project and based also on results of BIODROUGHT project (www.biodrought.eu). |
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