AME 56:205-215 (2009)  -  DOI:

Short-term variability in primary productivity during a wind-driven diatom bloom in the Gulf of Eilat (Aqaba)

David Iluz1,*, Gal Dishon1, Elisa Capuzzo2, Efrat Meeder3, Rosa Astoreca4, Vivian Montecino5, Petr Znachor6, Dilek Ediger7, John Marra8

1The Mina & Everard Goodman Faculty of Life Sciences, and The Department of Geography and Environment, Bar-Ilan University, Ramat-Gan 52900, Israel
2School of Life Sciences, Napier University, Edinburgh, UK
3Interuniversity Institute for Marine Sciences, Eilat, and the Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
4Ecologie des Systèmes Aquatiques, Faculté des Sciences, Université Libre de Bruxelles, Belgium
5Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
6Laboratory of Phytoplankton Ecology, Institute of Hydrobiology, Biology Centre ASCR, Czech Republic
7Chemistry and Environment Institute, Gebze-Kocaeli, Turkey
8Brooklyn College of the City University of New York, Brooklyn, New York, USA

ABSTRACT: In the northern Gulf of Eilat (Aqaba), sharp increases in the biomass of diatoms and rates of primary production occurred in April 2008. Within 24 h, diatom abundance rose from 8 × 103 to 228 × 103 cells l–1, and photosynthetic rates concomitantly doubled from 15 to 35 µg C l–1 d–1. Water transparency declined, as indicated by the vertical diffusion attenuation coefficient Kd for photosynthetically active radiation (PAR), which increased from 0.076 to 0.090 m–1 and decreased the euphotic depth from 60 to 45 m. During this time, a significant increase in silica deposition by the diatoms was also detected. We attribute the mentioned changes in environmental characteristics to wind-generated surface currents. Strong winds (up to 10 m s–1) during the measurements enriched the surface layers with unusually high nutrient concentrations within <1 d. Hence, primary production rates were observed at a relatively eutrophic nearshore station (MP) and pelagic station (A1, 10 km towards the center of the Gulf). They were compared with rates measured on the subsequent day. Values measured were twice as high as those at the pelagic station during the previous calm day. Routine monitoring programs with monthly or semi-weekly sampling are thus likely to miss brief but significant injections of nutrients, leading to the underestimation of seasonal and annual primary production. Our results demonstrate the impacts of transient events on the function and annual yield of aquatic ecosystems.

KEY WORDS: Primary production · Wind speed · Upwelling · Phytoplankton · Diatom blooms · Phytoplankton absorption

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Cite this article as: Iluz D, Dishon G, Capuzzo E, Meeder E and others (2009) Short-term variability in primary productivity during a wind-driven diatom bloom in the Gulf of Eilat (Aqaba). Aquat Microb Ecol 56:205-215.

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