PARENT SESSION
Poster Session 19: Biodiversity
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

GGenetic diversity drives ecosystem functions in marine monodominant macrophyte stands.

Ehlers, Anneli¹, Worm, Boris², Reusch, Thorsten³, ¹ Leibniz-Institut für Meereswissenschaften, Kiel, Germany² Biology Department, Halifax, NS, Canada³ Max-Planck-Institut für Limnologie, Plön, Germany

ABSTRACT- Marine macrophyte stands often consist of only one or a few species, but are differentiated into numerous genotypes (clones). We tested whether genetic diversity is important for ecosystem productivity and resilience in a marine macrophyte system. Here we present results of two mesocosm-experiments conducted with one-, three- and six- genotype mixtures of eelgrass Zostera marina. In the first experiment, fertilizer was added to the water column to simulate increasing eutrophication. In the second experiment, half of the tanks were heated experimentally, simulating a climatic warming event. In both experiments, strong differences in performance and morphology among six eelgrass-genotypes were found. Both stressors showed a strong negative impact on the performance of plants. The results of the fertilization experiment showed an interaction between the highest diversity level and eutrophication, indicating higher ecological resistance of genetically diverse plots. Results from the second experiment conducted under increased water temperatures showed increased belowground eelgrass biomass and shoot density with increasing genotypic diversity. Our results demonstrate marked differentiation between genotypes of a monodominant macrophyte system and some positive effects of genotypic diversity on seagrass productivity and resistance to environmental stress.

Key words: genetic diversity, ecosystem functioning, seagrass, ecological resilience