AME 56:81-91 (2009)  -  DOI: https://doi.org/10.3354/ame01314

Determining the availability of phosphate and glucose for bacteria in P-limited mesocosms of NW Mediterranean surface waters

Tsuneo Tanaka1,4,*, T. Frede Thingstad1, Josep M. Gasol2, Clara Cardelús2, Jan Jezbera3, M. Montserrat Sala2, Karel Šimek3, Fernando Unrein3

1Marine Microbiology Research Group, Department of Biology, University of Bergen, Jahnebakken 5, PO Box 7800, 5020 Bergen, Norway
2Institut de Ciències del Mar (CSIC), Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain
3Biological Centre of the Academy of Sciences of the Czech Republic, v.v.i., Institute of Hydrobiology, Na Sádkách 7, 37005 České Budějovice, Czech Republic
4Present address: Aix-Marseille University, CNRS, LOPB-UMR 6535, OSU/COM, Campus de Luminy-Case 901, 13288 Marseille CEDEX 09, France

ABSTRACT: Availability of phosphate for phytoplankton and bacteria and of glucose for bacteria was studied in mesocosms using NW Mediterranean coastal water with added phosphate, glucose, or a combination of both. We observed an initial increase of bacterial production in all mesocosms, a continuous increase of particulate P only in the P-enriched mesocosms, and a greater accumulation of dissolved organic C in the glucose-enriched mesocosms compared to those enriched by both glucose and P. This suggests that the water used was initially P-starved with a certain pool of degradable organic C available for bacteria. Specific phosphate affinities indicated a P limitation for the bacterial community in all mesocosms. Specific glucose affinities were different between the mesocosms but much lower than the theoretical maximum predicted from the diffusion-limited model. This suggests that the glucose pool was not a strong controlling factor of bacterial growth. In the P-enriched mesocosms, it is indicated that the extent of P limitation shifted from highest to lowest, while the available pool of glucose steadily decreased during the experiment. The explanation suggested for these observations is that phosphate regeneration was enhanced in the plankton food web, by which bacterial carbon demand became higher than the degradable organic C produced in the P-enriched mesocosms.


KEY WORDS: Specific affinity · Nutrients · P limitation · Degradable organic carbon · Mesocosm · Blanes Bay · NW Mediterranean


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Cite this article as: Tanaka T, Thingstad TF, Gasol JM, Cardelús C and others (2009) Determining the availability of phosphate and glucose for bacteria in P-limited mesocosms of NW Mediterranean surface waters. Aquat Microb Ecol 56:81-91. https://doi.org/10.3354/ame01314

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