Microscale Vertical Profiles of N2 Fixation, Photosynthesis, O2, Chlorophyll a, and Light in a Cyanobacterial Assemblage

摘要: Profiles of 15N2 fixation, O2 production (gross photosynthesis), concentration, chlorophyll a and photon fluence rates were measured with 50-μm resolution in colonies the heterocyst-forming cyanobacterium Nostoc parmelioides. Microelectrode measurements made after 20 h incubation under gas. Colonies frozen, sections prepared by using freezing microtome analyzed for 15N enrichment concentration. exhibited steep spatial gradients gross photosynthesis, irradiance, highest values generally occurring at surface. irradiance all showed positive correlations, but concentrations varied independently photosynthesis irradiance. Forty-four percent variation incorporation was explained (a correlation) when expressed per unit biomass (chlorophyll a).