SEDIMENT ROUGHNESS AND MOISTURE AS KEY FACTORS FOR STREAM BENTHIC MACROINVERTEBRATES RESISTANCE DURING THE DROUGHT PERIOD
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| Year of publication | 2017 |
| Type | Conference abstract |
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| Description | Hydrological regime of many small streams is significantly altered by human activities or climate change, which can result in a complete dry-out mostly during the summer season. While some of the taxa do not survive, other can resist the disturbance within wet streambed. Macroinvertebrate taxa that are able to penetrate into wet substrate or have specific adaptations for resistance in wet stream bed can survive on a site impacted by drought. The key factors affecting taxa survival is substrate roughness and its moisture. Desiccation resistance of selected (model) macroinvertebrate taxa (Gammarus fossarum, Ephemera danica, Baetis sp., Pisidium sp. and Oligochaeta (mixture of Limnodrilus/Tubifex sp.) was tested in a laboratory experiment. The main aim of the study was to test the ability of the taxa to penetrate the substrate and the length of their possible survival there. We used three substrate types with different grain size (2-4 mm, 7-10 mm and 20-32 mm), under 7 cm layer of the substrate there was 3 cm layer of permanently watered sand that simulated aquatic refugium (hyporheal). We made five subsequent controls during a period of 32 days from the beginning of the experiment. Soil moisture, air temperature and humidity were measured during the experiment. Aquatic Oligochaetes and Pisidium sp. showed the best ability to get into wet substrate and survive there for a long period. On the contrary, Baetis sp. could not survive even in wet refugium. G. fossarum and E. danica revealed various abilities depending on the substrate type. |
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