FROM CELLULAR TRAITS TO POPULATION DYNAMICS: INTRASPECIFIC VARIATION IN THE EFFECTS OF CO2 AND NITROGEN ON A TOXIC CYANOBACTERIUM

Eutrophication and elevated pCO₂ impact aquatic ecosystem functioning in a multitude of ways, including proliferation of harmful cyanobacterial blooms. These alterations in biogeochemical cycles impact harmful cyanobacteria, which manifests as shifts in a range of their traits like growth, nutrient uptake, and toxin production. As such, we can use a trait-based approach to mechanistically understand the cellular processes underlying the success of toxic cyanobacterial species along environmental gradients. In this study, we assessed how changes in CO₂ levels combined with low and high nitrogen (N) availabilities affected growth, nitrogen uptake, cellular elemental stoichiometry, and toxin production in three toxic strains of Microcystis aeruginosa. Our findings showed interactive effects between CO₂ and N on growth, stoichiometry, and toxin production consistently across strains. Regarding nitrogen growth affinities, the three strains showed differential responses, which likely will have implications for population dynamics across increasing CO₂ levels. So far, our findings show stoichiometrically predictable responses in key traits, notably toxin synthesis, which will support our understanding of the future combined effects of CO₂ and nitrogen variation on cyanobacterial growth, population dynamics, and bloom toxicity.

Primary Presenter: Savannah Sarkis, Netherlands Institute of Ecology (NIOO-KNAW) (s.sarkis@nioo.knaw.nl)

Authors:

Savannah Sarkis, Netherlands Institute of Ecology (NIOO-KNAW)  (s.sarkis@nioo.knaw.nl)

Jing Liu, Netherlands Institute of Ecology (NIOO-KNAW)  (j.liu@nioo.knaw.nl)

Uwe John, Alfred Wegener Institute for Polar and Marine Research (AWI)  (uwe.john@awi.de)

Jef Huisman, University of Amsterdam  (j.huisman@uva.nl)

Dedmer Van de Waal, Netherlands Institute of Ecology (NIOO-KNAW)  (d.vandewaal@nioo.knaw.nl)