K Van der Gucht

Body size and dispersal mode as key traits determining metacommunity structure of aquatic organisms

Relationships between traits of organisms and the structure of their metacommunities have so far mainly been explored with meta-analyses. We compared metacommunities of a wide variety of aquatic organism groups (12 groups, ranging from bacteria to fish) in the same set of 99 ponds to minimise biases inherent to meta-analyses. In the category of passive dispersers, large-bodied groups showed stronger spatial patterning than small-bodied groups suggesting an increasing impact of dispersal limitation with increasing body size. Metacommunities of organisms with the ability to fly (i.e. insect groups) showed a weaker imprint of dispersal limitation than passive dispersers with similar body size. In contrast, dispersal movements of vertebrate groups (fish and amphibians) seemed to be mainly confined to local connectivity patterns. Our results reveal that body size and dispersal mode are important drivers of metacommunity structure and these traits should therefore be considered when developing a predictive framework for metacommunity dynamics.

MULTI-GROUP BIODIVERSITY IN SHALLOW LAKES ALONG GRADIENTS OF PHOSPHORUS AND WATER PLANT COVER

This study aimed at unraveling the structure underlying the taxon-richness matrix of shallow lakes. We assessed taxon richness of a large variety of food-web com- ponents at different trophic levels (bacteria, ciliates, phytoplankton, zooplankton, fish, macro-invertebrates, and water plants) in 98 shallow lakes from three European geographic regions: Denmark (DK), Belgium/The Netherlands (BNL), and southern Spain (SP). Lakes were selected along four mutually independent gradients of total phosphorus (TP), vege- tation cover (SUBMCOV), lake area (AREA), and connectedness (CONN). Principal-com- ponents analysis (PCA) indicated that taxon diversity at the ecosystem level is a multidi- mensional phenomenon. Different PCA axes showed associations with richness in different subsets of organism groups, and differences between eigenvalues were low. Redundancy analysis showed a unique significant contribution to total richness variation of SUBMCOV in all three regions, of TP in DK and SP, and of AREA in DK and BNL. In DK, several organism groups tended to show curvilinear responses to TP, but only one was significantly hump shaped. We postulate that the unimodal richness responses to TP that are frequently reported in the literature for many organism groups may be partly mediated by the unimodal response of macrophyte vegetation to lake productivity.

Biodiversity in European Shallow Lakes: a Multilevel-Multifactorial Field Study

This chapter is based on the premise that the precipitous decline in freshwa- ter wetlands and species can only be arrested through conservation and sus- tainable management at a large scale, based on water (usually river) basins. A number of approaches to large-scale freshwater wetlands conservation are presented and assessed to draw conclusions on future conservation priori- ties.

Two new Biscogniauxia species from Papua New Guinea

Biscogniauxia mucigera sp. nov. and B. waitpela sp. nov. are described and illustrated from specimens collected in Papua New Guinea. Biscogniauxia mucigera was found associated with the anamorphic state on dead branches. The anamorph of B. mucigera is also described from culture.

A new variety and combination for Hypoxylon citriforme

Hypoxylon citriforme , formerly placed in Hypoxylon sect. Applanata , is combined in Biscogniauxia. Biscogniauxia citriforme var. macrospora var. nov. is described and illustrated from specimens found in Papua New Guinea.