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Conference paper2016Peer reviewed

Disentangling the impacts of multiple stressors along a hydromorphological gradient on stream ecosystem structure and functioning

Truchy, Amelie; Ecke, Frauke; Johnson, Richard K.; Mckie, Brendan; Webb, JA; Costelloe, JF; CasasMulet, R; Lyon, JP; Stewardson, MJ


Hydropower accounts for 60% of Sweden's electrical supply, with hundreds of rivers dammed across the country. However, the impacts of these dams on stream biodiversity and ecosystem processes, such as litter decomposition or algal growth, have been poorly researched. Such processes underpin key ecosystem services delivered from freshwater environments, including provision of food and clean water and the mitigation of pollutants. To address these deficiencies, we assessed physico-chemical, community and functional responses along a hydromorphological gradient. We selected 10 streams from Western Sweden ranging from unregulated to strongly regulated by hydropower dams. The sites were characterised based on land use, water chemistry, riparian vegetation and hydrogeomorphological data, including discharge changes, the extent of ditching and channelization. A PCA on these variables allowed us to extract a first component used as a representative of the stream regulation gradient. Community structural variables include richness and Shannon diversity of four taxonomic groups (diatoms, invertebrates, macrophytes, fish), while functional responses include litter decomposition and algal productivity. Initial analyses indicate relatively strong functional responses along the gradient: variability in litter decomposition and algal growth rates decrease as hydroelectric regulation increase. However, there is little consistency among the taxonomic groups along the gradient: fish richness decreased while macrophyte and invertebrate abundances were the lowest at intermediate level of disturbance. These results would provide an additional dimension in the bioassessment of human impacts on aquatic ecosystems.

Published in

Title: Proceedings of the 11th International Symposium on Ecohydraulics
ISBN: 978-0-7340-5339-8


11th International Symposium on Ecohydraulics