Dry stream channels as attractive habitats for multiple biotic groups
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| Year of publication | 2024 |
| Type | Appeared in Conference without Proceedings |
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| Description | Current trajectories of climate change are manifested in the river networks of Central Europe by dramatic shifts from a perennial to an intermittent flow regime. Decrease of annual discharge is also associated with remarkable seasonal shifts in the flow duration, when first dry episodes can occur even in early spring (April-May) and could last until the cold season in winter (December-January) with the flow absence over half a year. Such prolonged dry episodes offer an extended time-window for stream colonisation by many terrestrial groups, which originally use habitats surrounding river channels. Newly occurred biotope of dry riverbed could provide attractive environment (e.g., exposed sandy and gravel bars), that is not available in regulated rivers and anthropogenically modified floodplain. Effects of stream drying on aquatic biota were more intensively studied in the last decade also in temperate Central Europe; however, interactions between terrestrial and aquatic groups are still poorly examined. Nevertheless, we can expect multiple impacts of invading terrestrial fauna and flora on aquatic biota during the dry phase (e.g., predation in pools and dry bottom, streambed ploughing, colonisation by terrestrial plants etc.). Additionally, some of these effects could persist and consequently affect aquatic communities after the flow resumption. We show some examples of exploitation of dry channels by terrestrial groups, which could affect aquatic biota such as macroinvertebrates and fish (e.g., predation by terrestrial invertebrates and large vertebrates as wild boars or piscivorous birds). Moreover, some terrestrial invertebrates and plants including endangered taxa could recognise dry riverbed as attractive habitat, which enable them successful reproduction and expansion of populations. Such long-time dry reaches with sufficient light exposition are also rapidly colonised by terrestrial vascular plants, which could later offer food resources and shelter for aquatic macroinvertebrates in the early stages of recolonization after rewetting. Contrary to our expectations, we also recorded few examples of an active movement of strictly aquatic stages or macroinvertebrates, which migrate not only within dry channels, but also actively immigrate to terrestrial riparian habitats several meters outside the channel. These findings shed a new light on the role of currently spreading habitats of intermittent streams, which emphasize an urgent need of their examination during progressing climate changes in the temperate zone of Central Europe. Research was supported by the projects H2020 DRYVER (869226) and TACR project SS06010258. |
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