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Aquatic Microbial Ecology

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AME 56:217-225 (2009)  -  DOI:

Transparent exopolymer particles (TEP) link phytoplankton and bacterial production in the Gulf of Aqaba

Edo Bar-Zeev1,*, Ilana Berman-Frank1, Noga Stambler1,2, Evaristo Vázquez Domínguez3, Tamar Zohary4, Elisa Capuzzo5, Efrat Meeder6,7, David J. Suggett8, David Iluz1,2, Gal Dishon1, Tom Berman4

1The Mina & Everard Goodman Faculty of Life Sciences, Bar Ilan University, Ramat Gan 52900, Israel
2Department of Geography and Environment, Bar-Ilan University, Ramat-Gan 52900, Israel
3CSIC, Institut de Ciències del Mar, Passeig Marítim de la Barceloneta, 39-43, 08003 Barcelona, Spain
4Israel Oceanographic and Limnological Research, The Yigal Allon Kinneret Limnological Laboratory, Tiberias 14102, Israel
5School of Life Sciences, Napier University, Edinburgh EH10 5DT, UK
6The Interuniversity Institute for Marine Sciences Coral Beach, POB 469, 88103 Eilat, Israel
7Institute of Earth Sciences, The Hebrew University Edmond J. Safra Campus, Jerusalem 91904, Israel
8Department of Biological Sciences, University of Essex, Colchester CO4 3SQ, UK

ABSTRACT: Variations in transparent exopolymer particles (TEP), bacterial biomass production (BP) and primary productivity (PP) were followed over 52 h at a deep water station in the Gulf of Aqaba (Eilat, Israel) during the spring, in April 2008. About 20 h after the start of the study, there was a short (~15 h) but intense storm event that probably caused a nutrient pulse and, subsequently, a brief outgrowth of diatoms in the euphotic layer. Concentrations of TEP and BP ranged from 23 to 228 µg gum xanthan equivalents l–1 and from 0.2 to 0.6 µg C l–1 h–1, respectively. Concentrations of TEP and BP were measured in unfiltered and in GF/C (1.2 µm)-prefiltered samples. Most of the TEP (59 ± 21% of total TEP, mean ± SD) were in the smaller (GF/C-filtered) size fraction (0.4–1.2 µm); however, after the crash of the diatom bloom, the majority of TEP were in the >1.2 µm size fraction. In the GF/C-filtered fraction, BP averaged 59 ± 12% and 93 ± 5% of total BP in the upper water column and from 300 m, respectively. Significant correlations were observed between TEP and BP, suggesting that active heterotrophic bacteria may have been associated with these particles. During the 3 d of our study, PP and BP in the euphotic zone averaged 480 and 225 mg C m–2 d–1, respectively, suggesting that about half or more of the primary produced carbon was metabolized by heterotrophic bacteria in the upper water column. Coincident with strong mixing caused by the storm, TEP concentrations decreased in the surface water and increased at depth. We suggest that TEP acted to link carbon flux between the primary producers and heterotrophic bacteria, and that the downward movement of TEP from the upper water layers may be an important process in transferring organic carbon to deeper waters of the Gulf of Aquaba. Sinking TEP could provide not only organic carbon substrates for associated bacteria but also form ‘hot spots’ of elevated microbial metabolism and nutrient cycling throughout the water column.

KEY WORDS: Transparent exopolymer particles · TEP · Bacterial productivity · Primary productivity · Carbon cycling · Size fractionation · Gulf of Aqaba

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Cite this article as: Bar-Zeev E, Berman-Frank I, Stambler N, Vázquez Domínguez E and others (2009) Transparent exopolymer particles (TEP) link phytoplankton and bacterial production in the Gulf of Aqaba. Aquat Microb Ecol 56:217-225.

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