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Nitrogen and phosphorus limitation of oceanic microbial growth during spring in the Gulf of Aqaba

Suggett, DJ and Stambler, N and Prášil, O and Kolber, Z and Quigg, A and Vázquez-Dominguez, E and Zohary, T and Berman, T and Iluz, D and Levitan, O and Lawson, T and Meeder, E and Lazar, B and Bar-Zeev, E and Medova, H and Berman-Frank, I (2009) Nitrogen and phosphorus limitation of oceanic microbial growth during spring in the Gulf of Aqaba. In: UNSPECIFIED, ? - ?.

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Abstract

Bioassay experiments were performed to identify how growth of key groups within the microbial community was simultaneously limited by nutrient (nitrogen and phosphorus) availability during spring in the Gulf of Aqaba's oceanic waters. Measurements of chlorophyll a (chl a) concentration and fast repetition rate (FRR) fluorescence generally demonstrated that growth of obligate phototrophic phytoplankton was co-limited by N and P and growth of facultative aerobic anoxygenic photoheterotropic (AAP) bacteria was limited by N. Phytoplankton exhibited an increase in chl a biomass over 24 to 48 h upon relief of nutrient limitation. This response coincided with an increase in photosystem II (PSII) photochemical efficiency (F v /F m), but was preceded (within 24 h) by a decrease in effective absorption crosssection (σPSII) and electron turnover time (τ). A similar response for τ and bacterio-chl a was observed for the AAPs. Consistent with the up-regulation of PSII activity with FRR fluorescence were observations of newly synthesized PSII reaction centers via low temperature (77K) fluorescence spectroscopy for addition of N (and N + P). Flow cytometry revealed that the chl a and thus FRR fluorescence responses were partly driven by the picophytoplankton (æ10 μm) community, and in particular Synechococcus. Productivity of obligate heterotrophic bacteria exhibited the greatest increase in response to a natural (deep water) treatment, but only a small increase in response to N and P addition, demonstrating the importance of additional substrates (most likely dissolved organic carbon) in moderating the heterotrophs. These data support previous observations that the microbial community response (autotrophy relative to heterotrophy) is critically dependent upon the nature of transient nutrient enrichment. © Inter-Research 2009.

Item Type: Conference or Workshop Item (UNSPECIFIED)
Additional Information: Published proceedings: Aquatic Microbial Ecology
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Jim Jamieson
Date Deposited: 06 Oct 2011 11:57
Last Modified: 16 Sep 2019 17:15
URI: http://repository.essex.ac.uk/id/eprint/847

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