Bicarbonate Transport and Extracellular Carbonic Anhydrase Activity in Bering Sea Phytoplankton Assemblages: Results from Isotope Disequilibrium Experiments

We used a14C isotope disequilibrium technique to provide quantitative estimates of both direct HCO3 -transport and extracellular CA activity in Bering Sea phytoplankton assemblages. The method revealed that direct HCO3 -transport was the dominant mechanism of inorganic C uptake in both coastal and o...

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Bibliographic Details
Published in:Limnology and oceanography 2006-09, Vol.51 (5), p.2111-2121
Main Authors: Martin, Cheryl L., Tortell, Philippe D.
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Biological and medical sciences
Carbon dioxide
Diatoms
Fundamental and applied biological sciences. Psychology
Isotopes
Marine
Market disequilibrium
Oceans
Phytoplankton
Radiocarbon
Sea transportation
Sea water
Sea water ecosystems
Seas
Synecology
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Summary:We used a14C isotope disequilibrium technique to provide quantitative estimates of both direct HCO3 -transport and extracellular CA activity in Bering Sea phytoplankton assemblages. The method revealed that direct HCO3 -transport was the dominant mechanism of inorganic C uptake in both coastal and open ocean waters, accounting for more than half of the total C flux to the phytoplankton. The relative importance of HCO3 -transport was not related to phytoplankton biomass, productivity, or ambient CO2concentrations at individual sampling stations. However, HCO3 -transport and total inorganic C uptake rates decreased in response to elevated CO2in direct manipulation experiments. Kinetic analysis of the14C time-course data revealed low levels of extracellular carbonic anhydrase activity at most stations. This activity was related to phytoplankton taxonomic compositions and/or CO2concentrations, but was relatively unaffected by direct CO2manipulations.
ISSN:0024-3590
1939-5590
DOI:10.4319/lo.2006.51.5.2111