Euro-limpacs Deliverables

ABSTRACT - DELIVERABLE 94

Report on indicator species or groups bound to key habitats in the investigated catchments

Running waters are characterised by strong hydrological and geo−morphological gradients which relate to highly dynamic processes of three types: hydrological (flooding, desiccation, surface and groundwater interactions) geo−morphological (channel bed degradation and aggradations, bank erosion etc.) and hydraulic processes (including high shear stress during spates, stagnation in dead−zones during low flows). A further key factor ruling the composition of aquatic organisms is thought to be water temperature. All the tangled parameters are addressed in EUROLIMPACS and will be covered by work package 2.
Within this work package 2 Subtask 2.2 deals with habitat preferences of indicator species on the habitat scale. Subtask 2.2 is closely related to Subtask 1.1 (Climate−hydromorphology interactions through changes in land−use and discharge: review of information relating selected study catchment across Europe and Subtask 2.1 (review of existing information on key taxa and functional groups relevant to the eight study catchments). Subtask 2.1 supplemented the results of subtask 1.1 which was finished at the end of first year of project duration. Regarding climatic/discharge scenarios and in view of the information from the report for subtask 1.1 an increase in temperature, a decrease in summer and an increase in autumn−winter precipitations and an increase of extreme daily precipitation is expected. Consequently, discharge will show a more dynamic regime, due to increases in extreme daily precipitation and in severity of droughts (Opatrilova et al. 2005).
The alternative key hypotheses are:
(i) that global change may cause hydro−morphological deterioration through intensification of land−use or through a more variable discharge regime that results in habitat modifications and losses; and alternatively,
(ii) that global change may cause significant improvement if, for example, human disturbances are withdrawn from floodplains due to more frequent flood events or as a result of floods that generate a near−natural habitat structure.

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