| Abstract | 1. Species assemblages of diatoms, rotifers, chydorids, planktonic crustaceans and chironomids were studied in 235 alpine lakes in the Alps, Pyrenees, Tatras (Western Carpathians), Retezat (Southern Carpathians) and Rila Mountains (Balkans).
2. For all taxonomic groups we found a hierarchical structure in the community assemblage using distinct scales of lake clustering (number of k-means groups) based on species composition similarity (Hellinger distance). We determined the optimal partition in assemblage types (i.e. number of lake clusters) for each taxonomic group by maximising the sum of the taxon indicative value (IndVal) and performed discriminant analyses, using environmental variables not conditioned by geographical patterns. Relevant environmental variables differed among and within taxonomic groups. Therefore the assemblages respond to a complex environmental mosaic, with the exception of diatom assemblages, which followed an acidbase gradient.
3. The significant environmental variables could be grouped into four general factors: lake size, tropho-dynamic status, acidbase balance and ice-cover duration (i.e., altitudinal gradient). Lake size was significant for the highest number of assemblage types; however, the most significant factor differed among taxonomic groups: acidbase balance for diatoms, lake size for rotifers, ice-cover duration for chydorids and planktonic crustaceans and tropho-dynamic status for chironomids. No single environmental typology accounted for the assemblage structure of all taxonomic groups.
4. However, defining ecological thresholds as values within environmental gradients at which the rate of change in assemblages is accelerated relative to points distant from that threshold, we were able to find specific threshold values for each of the four main general environmental factors identified, which were relevant across several taxonomic groups: 3 ha for lake area; 0.6 mg L)1 for dissolved organic carbon; 190 days for ice-cover duration and 200 leq L)1 for acid neutralising capacity. Above and below these values ecosystem organisation change substantially. They have direct applications in establishing lake typologies for environmental quality and biodiversity conservation programmes, and in improving predictions about global change impacts. |
| Authors | Catalan J., Barbieri M.G., Bartumeus F., Bitusik P., Botev I., Brancelj A., Cogalniceanu D., Manca M., Marchetto A., Ognjanova-Rumenova N., Pla S., Rieradevall M., Sorvari S., Stefkova E., Stuchlik E., Ventura M. |
| Text | 53134 2009 10.1111/j.1365 2427.2009.02286.x ISI Web of Science WOS 000271710100005 chironomids chydorids crustaceans diatoms metacommunities Ecological thresholds in European alpine lakes Catalan J., Barbieri M.G., Bartumeus F., Bitusik P., Botev I., Brancelj A., Cogalniceanu D., Manca M., Marchetto A., Ognjanova Rumenova N., Pla S., Rieradevall M., Sorvari S., Stefkova E., Stuchlik E., Ventura M. 1 Limnology Group, CEAB, CSIC, Blanes, Catalonia, Spain 2 Laboratorio Studi Ambientali, Lugano, Switzerland 3 Department of Ecology Evolutionary Biology Princeton Environmental Institute, Princeton University, Princeton, NJ, U.S.A. 4 Faculty of Science and Research Institute, Matthias Belius University, Banska Bystrica, Slovakia 5 Department of Hydrobiology, Institute of Zoology, Bulgarian Academy of Sciences, Sofia, Bulgaria 6 National Institute of Biology, Ljubljana, Slovenia 7 University Ovidius Constanta, Constanta, Romania 8 Department of Palaeontology Stratigraphy, Institute of Geology, Bulgarian Academy of Sciences, Sofia, Bulgaria 9 Department of Ecology, University of Barcelona, Barcelona, Spain 10 Department of Biological Environmental Sciences, University of Helsinki, Helsinki, Finland 11 Department of Hydrobiology, Institute of Zoology, Slovak Academy of Sciences, Bratislava, Slovakia 12 Institute for Environmental Studies, Faculty of Science, Charles University in Prague, Czech Republic 13 National Environmental Research Institute, Aarhus University, Silkeborg, Denmark 1. Species assemblages of diatoms, rotifers, chydorids, planktonic crustaceans and chironomids were studied in 235 alpine lakes in the Alps, Pyrenees, Tatras Western Carpathians , Retezat Southern Carpathians and Rila Mountains Balkans . 2. For all taxonomic groups we found a hierarchical structure in the community assemblage using distinct scales of lake clustering number of k means groups based on species composition similarity Hellinger distance . We determined the optimal partition in assemblage types i.e. number of lake clusters for each taxonomic group by maximising the sum of the taxon indicative value IndVal and performed discriminant analyses, using environmental variables not conditioned by geographical patterns. Relevant environmental variables differed among and within taxonomic groups. Therefore the assemblages respond to a complex environmental mosaic, with the exception of diatom assemblages, which followed an acidbase gradient. 3. The significant environmental variables could be grouped into four general factors lake size, tropho dynamic status, acidbase balance and ice cover duration i.e., altitudinal gradient . Lake size was significant for the highest number of assemblage types; however, the most significant factor differed among taxonomic groups acidbase balance for diatoms, lake size for rotifers, ice cover duration for chydorids and planktonic crustaceans and tropho dynamic status for chironomids. No single environmental typology accounted for the assemblage structure of all taxonomic groups. 4. However, defining ecological thresholds as values within environmental gradients at which the rate of change in assemblages is accelerated relative to points distant from that threshold, we were able to find specific threshold values for each of the four main general environmental factors identified, which were relevant across several taxonomic groups 3 ha for lake area; 0.6 mg L 1 for dissolved organic carbon; 190 days for ice cover duration and 200 leq L 1 for acid neutralising capacity. Above and below these values ecosystem organisation change substantially. They have direct applications in establishing lake typologies for environmental quality and biodiversity conservation programmes, and in improving predictions about global change impacts. 54 Published version Parole chiave chironomids, chydorids, crustaceans, diatoms, metacommunities, mountain lakes, rotifers, zooplankton articolo pubblicato 05_Fresh_biol_2009_Marina.pdf Articolo in rivista Blackwell Scientific Publications. 0046 5070 Freshwater biology Print Freshwater biology Print Freshw. biol. Print aldo.marchetto MARCHETTO ALDO marinamarcella.manca MANCA MARINA MARCELLA TA.P04.016.004 Ecologia teorica e applicata degli ecosistemi acquatici |
