Stream drying acceleration in Central Europe: Trends in aquatic and terrestrial communities
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| Year of publication | 2019 |
| Type | Conference abstract |
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| Description | Stream intermittency has expanded in the last 5 years over dominant part of the Czech Republic, where more than 50% streams at 1-4 Strahler order belongs to risk of frequent drying. Cumulative effect of supraseasonal drought can lead to a gradual change not only in aquatic communities but also triggers shifts in terrestrial assemblages which can use dry riverbed as a new type of habitat. Gravel bars can be rapidly colonised by vascular plants growing in surrounding riparian habitats/catchment and emerging from the sediment seedbank. For terrestrial invertebrate specialists can be the bare riverbed suitable refuges in the landscape lacking such habitats due to absence of natural disturbances. Similarly big terrestrial mammals can search for food in dry channels during flow cessation and later use them as preferable migratory corridors. Contrary to the expanding niche for terrestrial organisms, aquatic macroinvertebrates experience progressive reduction of habitats and time span to complete their life cycles. In response to this some taxa strongly reduced populations in previously perennial reaches. For very first time we observed new phenomena of delayed winter flow resumption (2-3 months latter then typically) associated with freezing of dry riverbed. All these new factors can lead due to its very fast onset to unpredictable changes in community structure and functioning (e.g. reduction of leaf packs decomposition by absence of aquatic macroinvertebrate autumn generations). Our research project (supported by grant LTC17017) explore some of these impacts using highly dynamic communities of rapidly changing streams in continental humid climate of Central Europe. |
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