2nd International Workshop on Conservation Biology

The structural and functional role of river bed sediments and gravel bars: implications for conservation ecology

Not scheduled

UP FAMNIT, Koper, Slovenia

Speaker

Dr Nataša Mori (Research Associate)

Description

The riverscape in its natural state is composed of a variety of habitats due to geomorphological features, ranging from wetted river bed sediments, to occasionally flooded gravel bars and islands. Especially in floodplain areas, the riverscape heterogeneity substantially increases. This contribution reviews the importance of those habitats for river ecosystem functionality and emphasise the major issues that should be addresses within future scientific research, and also within river management and conservation planning in Slovenia. The wetted river bed sediments are important habitats for diverse surface and groundwater invertebrate species. In the river reaches, connected with alluvial aquifers, the presence of groundwater species is expected to be high. The sampling of the rivers within Sava catchment confirmed those expectations (Mori et al., 2012). There is a strong need for classification of such habitats on the basis of biodiversity indices and a need for prioritisation of the most important areas. Secondly, the important part of decomposition and mineralization is taking place in the river sediments by biofilm and invertebrates during water flow through the interstitial spaces. In the Soča River, the floodplain islands were the areas with the highest sediment respiration activity demonstrating the importance of those habitats for nutrient cycling in the rivers. Similarly, biofilm from the river bed sediments was more active in deeper layers in comparison to the surface indicating that majority of nutrient processing is taking place within the river sediments. In conclusion, the river channel in near pristine conditions, with well developed sediment layer, and a mosaic of gravel bars and islands support high biodiversity and maintain nutrient cycling processes. However, the management of river corridors usually prioritize flood protection by introducing river channelization and do not consider the ecological importance of river bed sediments and gravel bars. Mori, N., Simčič, T., Žibrat, U., and Brancelj, A. (2012) The role of river flow dynamics and food availability in structuring hyporheic microcrustacean assemblages: a reach scale study, Fundamental and Applied Limnology/Archive fur Hydrobiologie 180, 335-349.