The effect of CO2 on the photosynthetic physiology of phytoplankton in the Gulf of Alaska

• DOI: 10.4319/lo.2010.55.5.2011
• Publication Date: 2010-08-08T09:31:21Z
• Authors: Brian M. Hopkinson; Yan Xu; Dalin Shi; Patrick J. McGinn; François M. M. Morel
• Keywords: Microcosm; Photosynthetic efficiency

In the high‐nutrient, low‐chlorophyll waters of Gulf Alaska, microcosm manipulation experiments were used to assess effect CO 2 on growth and primary production under iron‐limited iron‐replete conditions. As expected, iron had a strong photosynthesis. A modest variable stimulation biomass by (high : 77–122 Pa; low 11‐17 Pa) was observed both conditions, though near limit precision our measurements in slow‐growing low‐iron experiments. Physiological acclimations responsible for changes assessed. Under at high appeared result from an increase photosynthetic efficiency, which we attribute energy savings down‐regulation carbon concentrating mechanisms. some cases, iron‐rich proteins (PsbA, PsaC, cytochrome b 6 ) down‐regulated elevated controls. there rate This unexpectedly supported reductions cellular loss, most likely decreased respiration. We speculate that this may be due acclimation pH rather than . The variability responses among did not appear caused differences phytoplankton community structure reflect sensitivity net response antagonistic effects several parameters co‐vary with