PARENT SESSION
Symposium 16: Incorporating trophic diversity into the biodiversity-ecosystem functioning debate: Lessons from aquatic ecosystems
Organized by: P McIntyre, K France, JE Duffy, and AS Flecker
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 517 A, Level 5, Palais des congrès de Montréal
Consumer and prey diversity effects on trophic interactions: case studies from closed and open systems.
Hillebrand, Helmut*,1, Gamfeldt, Lars2, Jonsson, Per2, Matthiessen, Birte3, 1 Botanical Institute, Cologne, Germany2 Tjärnö Marine Biological Laboratory, Strömstad, Sweden3 Leibniz-Institute for Marine Science, Kiel, Germany
ABSTRACT- The loss of species especially on the consumer level has been shown to affect ecosystem processes, but most experiments to date have only analyzed effects of diversity reduction in experiments closed for immigration and emigration. We manipulated the presence and richness of benthic invertebrate grazers in an outdoor experiment with closed and with connected local habitats, respectively. Opening the system for dispersal strongly altered the effect of grazer richness on algal biomass production and grazing rates. In the closed systems, we found significant net biodiversity effects indicating that algal biomass production decreased and grazing rate increased with grazer richness. In the connected systems, strong immigration and emigration dynamics were observed and initial grazer richness had no effect on grazing rate or algal biomass. Species identity effects were generally strong and partially overrode the diversity effects. Also algal nutrient retention was affected by grazer identity and richness. We conclude that diversity effects profoundly differ in open and closed systems.
Key words: diversity effects, marine coastal communties, metacommunity dynamics