PARENT SESSION
Contributed Oral Session 74: Biodiversity: Aquatic Systems
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 513 C, Level 5, Palais des congrès de Montréal
Community structure in multiple aquatic organism groups: Patterns of concordance along gradients of water plant cover, total phosphorus, connectedness and lake size.
Declerck, Steven*,1, Jeppesen, Erik2, 6, Vyverman, Wim3, Conde Porcuna, José Maria4, Zwart, Gabriel5, De Meester, Luc1, 1 Laboratory of Aquatic Ecology, KULeuven, 3000 Leuven, Belgium2 National Environmental Research Institute, 8600 Silkeborg, Denmark6 Dept. of Plant Biology, University of Aarhus, 8230 Riskov, Denmark3 Section of Protistology and Aquatic Ecology, Ugent, 9000 Gent, Belgium4 Institute of Water Research, University of Granada, 18071 Granada, Spain5 Centre for Limnology, NIOO-KNAW, 3631 Nieuwersluis, The Netherlands
ABSTRACT- In the framework of the EU project "Biodiversity and Human Impact in Shallow Lakes" (BIOMAN) we sampled a large variety of food web components (bacteria, ciliates, phytoplankton, zooplankton, fish, and macrophytes) in 98 shallow lakes from three geographic regions within Europe (Denmark, Belgium/The Netherlands and the south of Spain). One major objective of the study was to assess the degree of association in community composition between different organism groups across multiple trophic levels of the food web. We also studied the generality of associations between community composition and four key variables: (1) total phosphorus content, (2) vegetation cover, (3) lake size, and (4) degree of connectedness. Because these variables often tend to be correlated (e.g. phosphorus and water plant cover) the selection design of the lakes aimed at keeping the four key variable gradients mutually independent. The relative importance of the variables in explaining community composition of different organism groups differed between geographic regions. In Belgium/The Netherlands and in Denmark submerged vegetation cover and lake size were found to be the most important explanatory variables affecting the highest number of organism groups. In these regions, the explanatory power of TP was rather modest (only two organism groups explained in Belgium) whereas no effects were found for the degree of connectedness. Conversely, in Spain, TP explained community variation in all of the studied organism groups, whereas the importance of vegetation was restricted to bacteria and phytoplankton. In this region, no significant effects were found for area and connectedness. Our results indicate that water plant vegetations are important in structuring the communities of aquatic organisms independently of the amount of nutrients that are available. Furthermore, shallow lake communities from different geographic regions appear to be structured by different factors and mechanisms.
Key words: community ecology, shallow lake, water plants, nutrients