Incidence of phytoplankton and environmental conditions on the bacterial ammonium uptake in a subtropical coastal lagoon

Submitted: 2 July 2013
Accepted: 27 September 2013
Published: 13 March 2014
Abstract Views: 2818
PDF: 850
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We analyzed the coupling between bacterioplankton and phytoplankton in Laguna de Rocha through an experimental approach. A freshwater zone of high turbidity and macrophytes growth and a brackish zone of higher light penetration and lower macrophytes biomass characterize this coastal lagoon. It has been shown that dissolved inorganic nitrogen, especially NH4+, has decreased to undetectable levels during the last decade. One hypothesis for this trend is the rapid removal by phytoplankton and bacterioplankton uptake. In an attempt to test this, we performed incubations using lagoon water from both zones split in two treatments (pre-filtered by 1.2 µm and unfiltered water) and amended with 15N-NH4+. After 4 h incubation we found that in both zones bacterioplankton showed significantly higher NH4+ uptake rates when incubated together with phytoplankton and that uptake rates of both microbial communities were higher in freshwater incubations. These results suggest that bacterial NH4+ uptake would be coupled to phytoplankton-derived exudates and hence that depletion of dissolved NH4+ in this system could be linked to rapid microbial uptake. The degree of this coupling would vary according to hydrological dynamics in this ecosystem.



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Supporting Agencies

Germán Pérez, Instituto de Investigaciones Biológicas Clemente Estable

Depto. Microbiología

Investigador Asistente

Laura Farías, Universidad de Concepción

Departamento de Oceanografía

Profesor Asistente

Camila Fernandez, UPMC Univ. Paris 06 and CNRS, UMR 7621
Researcher CNRS, Laboratory of Microbial Oceanography
Daniel Conde, Universidad de la República

Sección Limnología,  Facultad de Ciencias

Claudia Piccini, Instituto de Investigaciones Biológicas Clemente Estable

Departamento de Microbiología

How to Cite

Pérez, Germán, Laura Farías, Camila Fernandez, Daniel Conde, and Claudia Piccini. 2014. “Incidence of Phytoplankton and Environmental Conditions on the Bacterial Ammonium Uptake in a Subtropical Coastal Lagoon”. Journal of Limnology 73 (1).

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