Role of invertebrate dispersal pathways in intermittent streams recolonisation after rewatering – an in situ experimental study
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| Year of publication | 2024 |
| Type | Conference abstract |
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| Description | The dispersal abilities of aquatic organisms and their recolonisation abilities are generally underexplored in major biotic groups. This deficiency is a principal obstacle to understanding dispersal as a regional process structuring ecological communities, especially in spatiotemporally dynamic intermittent streams. Freshwater invertebrates are commonly spread inhabitants of inland aquatic systems, characterised as frequent, widespread dispersers able to reflect environmental conditions and their changes with a fast response at the species, population or community level. Stream intermittency represents a hydrological disturbance acting as an environmental filter providing intense selection pressure on instream biota – it significantly regulates population and community structure and dynamics particularly in current period of accelerated climate change. We tried to experimentally examine different recolonisation pathways used by benthic macroinvertebrates in terms of both taxonomic and functional community composition and evaluate their potential for successful community recovery after the drying period, expressed in total abundance and biomass. We considered four possible recolonisation pathways (i.e., downstream, upstream, hyporheic and aerial) with corresponding experimental units installed in situ, where only one of the mentioned recolonisation ways was allowed. Each treatment was represented by three replicates composed of wired boxes filled with an artificial gravel substrate exposed in a stream for two weeks. Significant differences among treatments were evident in the alpha-diversity indices; Shannon's diversity index was lowest in the hyporheic treatment, whereas the taxa richness and total abundance were lowest in the aerial treatment. Total biomass was highest in the hyporheic treatment, despite its lowest biodiversity. Two invertebrate groups, chironomids and crustaceans, dominated all the treatment types. The analysis of species traits showed different metacommunity structures in each treatment. Hyporheic treatments were frequently populated by inhabitants preferring sandy and gravel substrates, or species typical for a hyporheic zone. Species with flexible life cycles predominantly colonised aerial treatments. In upstream treatments dominated species from lower stream zones or species typical for standing waters, whereas species from upper stream sections were less frequent. While downstream drift was the most favourable pathway regarding biodiversity, the hyporheic pathway was the most important recolonisation way considering biomass. According to our study, the aerial and upstream recolonisation pathways have only a marginal contribution to community recovery after rewatering in a short-term horizon. The project was supported by the H2020 project DRYvER (869226). |
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