CO2 influence on oxygen dynamics and net primary production of the microphytobenthos : an experimental approach

• Production of organic matter by phototrophs requires inorganic carbon,which in aquatic systems is taken up from the water column, sediment oratmosphere. Observations on a microphytobenthic mat overlaid with 2 mm of waterand atmospheric air showed a tight balance between consumption and production ofoxygen and, therefore, a bimodal pattern in the Net Primary Production (NPP).Enrichment of the air with CO2 led to an enhancement of the NPP of a community,while the removal of all CO2 from the air resulted in no NPP and a linear O2 gradientfrom the overlying water to the lower part of the mat. The distribution and rates ofgross photosynthetic oxygen production, measured as the oxygen decline within oneto twos after light-dark shifts, showed little response to CO2 depletion, suggesting thatthe photosynthetic electron flow was primarily redirected from CO2 fixation tophotorespiration. In nature, the observed control of NPP by atmospheric CO2concentration should be most pronounced in shallow-water and intertidal systems,and the productivity in these ecosystems may therefore be steadily increasing alongwith the increase in atmospheric CO2 concentration. 

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Naturgeografi (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Physical Geography (hsv//eng)

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