The effects of nutrient additions on particulate and dissolved primary production and metabolic state in surface waters of three Mediterranean eddies
| Type | Article | ||||||||
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| Date | 2011 | ||||||||
| Language | English | ||||||||
| Author(s) | Lagaria A.1, 2, Psarra S.1, Lefevre D.3, Van Wambeke France3, Courties C.4, 5, Pujo-Pay M.6, 7, Oriol L.6, 7, Tanaka T.8, Christaki U.2 | ||||||||
| Affiliation(s) | 1 : Hellen Ctr Marine Res, Inst Oceanog, Iraklion 71003, Crete, Greece. 2 : INSU CNRS Univ Lille Nord France, Lab Oceanol & Geosci, ULCO, UMR8187, F-62930 Wimereux, France. 3 : INSU CNRS Univ Mediterranee, Ctr Oceanol Marseille, LMGEM, Lab Microbiol Geochim & Ecol Marines,UMR6117, F-13288 Marseille 9, France. 4 : INSU CNRS, Observ Oceanol Banyuls, UMS2348, F-66650 Banyuls Sur Mer, France. 5 : Univ Paris 06, Observ Oceanol Banyuls, UMS2348, F-66650 Banyuls Sur Mer, France. 6 : INSU CNRS Observ Oceanol, Lab Oceanog Microbienne, UMR7621, F-66650 Banyuls Sur Mer, France. 7 : Univ Paris 06, Lab Oceanog Microbienne, UMR7621, Observ Oceanol, F-66650 Banyuls Sur Mer, France. 8 : INSU CNRS Univ Mediterranee, Lab Oceanog Phys & Biogeochim, LOPB, Ctr Oceanol Marseille,UMR6535, F-13288 Marseille 9, France. |
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| Source | Biogeosciences (1726-4170) (Copernicus Gesellschaft Mbh), 2011 , Vol. 8 , N. 9 , P. 2595-2607 | ||||||||
| DOI | 10.5194/bg-8-2595-2011 | ||||||||
| WOS© Times Cited | 22 | ||||||||
| Abstract | We examined the effects of nutrient additions on rates of (14)C-based particulate and dissolved primary production as well as O(2)-based metabolic rates in surface waters (8 m) of three anticyclonic eddies, located in the Western, Central and Eastern Mediterranean. Ship-board microcosm experiments employing additions of inorganic nitrogen (+N) and phosphorus (+P), alone and in combination (+NP), were conducted in June/July 2008 during the BOUM (Biogeochemistry from the Oligotrophic to the Ultra-oligotrophic Mediterranean) cruise. In all three experiments, particulate primary production was significantly stimulated by the additions of nitrogen (+N, +NP) while no effect was observed with the addition of phosphorus alone (+P). Percent extracellular release of photosynthate (PER) displayed the lowest values (4-8%) in the +NP treatment. Among the three treatments (+N, +P, +NP), the +NP had the strongest effect on oxygen metabolic rates, leading to positive values of net community production (NCP>0). These changes of NCP were mainly due to enhanced gross primary production (GPP) rather than reduced dark community respiration rates (DCR). In all three sites, in +NP treatment autotrophic production (whether expressed as GPP or PP(total)) was sufficient to fulfil the estimated carbon requirements of heterotrophic prokaryotes, while addition of nitrogen alone (+N) had a weaker effect on GPP, resulting in metabolically balanced systems. At the three sites, in treatments with N (+N, +NP), phytoplankton and heterotrophic prokaryote production were positively correlated. Heterotrophic conditions were observed in the Control and +P treatment at the central and eastern sites, and autotrophic production was not sufficient to supply estimated bacterial carbon demand, evidence of a decoupling of phytoplankton production and consumption by heterotrophic prokaryotes. | ||||||||
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