HOW BIODIVERSITY MODULATES BLOOM FORMATION: EVIDENCE FROM NATURAL PHYTOPLANKTON COMMUNITIES

Phytoplankton communities in freshwater systems are characterized by their capacity to form rapid, transient biomass increases, known as blooms, in response to shifting abiotic and biotic conditions. The ability of potential bloom species to monopolize resources depends on their life-history traits, their ecophysiological alignment with environmental conditions, and interactions shaped by community diversity. Diversity can influence bloom dynamics through two opposing mechanisms: selection effects, where high diversity increases the likelihood that a highly competitive species dominates, and complementarity effects, where diverse assemblages partition resources more efficiently, reducing the chance that any single species achieves bloom-level dominance. Grazing pressure further modulates these processes by altering resource monopolization and biomass accumulation. We examined potential bloom formations in natural phytoplankton communities spanning a broad diversity gradient and shaped by long-term environmental history. Communities of naturally different diversity were collected from multiple freshwater lakes and subjected to a mesocosm experiment manipulating grazing and nutrient supply. We quantified community- and species-level bloom metrics across the diversity gradient and compared these results to previous laboratory experiments using artificial communities.  

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Maria Stockenreiter, Ludwig-Maximilians-Universität München (stockenreiter@biologie.uni-muenchen.de)

Authors:

Sophia Kopp, Ludwig-Maximilians-Universität München  (Sophia.Kopp@campus.lmu.de)

Kenza Wahbi-Fusier, European Institute for Marine Studies  (kenza.wahbifusier@univ-brest.fr)

Philippe Pondaven, European Institute for Marine Studies  (philippe.pondaven@univ-brest.fr)

Sabine Wollrab, Leibniz-Institute of Freshwater Ecology and Inland Fisheries  (sabine.wollrab@igb-berlin.de)

Patch Thongthaisong, Leibniz-Institute of Freshwater Ecology and Inland Fisheries  (patch.thongthaisong@igb-berlin.de)

Herwig Stibor, Ludwig-Maximilians-Universität München  (stibor@bio.lmu.de)