Aquatic Sciences Meeting, Albuquerque 2001
|SS11 Warm Oligotrophic Waters (Environmental Connections)|
|Date: Monday, February 12, 2001, Time: 3:45:00 PM|
|Stambler, N, , Bar-Ilan University, Ramat-Gan, Israel, firstname.lastname@example.org|
|THE UNDERWATER LIGHT FIELD IN THE GULF OF AQABA (EILAT), RED SEA: INFLUENCE OF PHYTOPLANKTON AND NON-LIVING SUBSTANCES (1995-2000).|
|The underwater light field in the Gulf of Elat was characterized on the basis of data collected at station A1, during 1995-2000. The euphotic zone ranged in depth from 125 to 70m. The vertical attenuation coefficient, Kd (PAR) averaged from the surface down to 110m depth, showed a seasonal fluctuation between a summer minimum of 0.04 and a spring maximum of 0.065m-1.|
Kd for the discrete wavelengths between 400-700nm had its minimal value of 0.1 m-1 in the blue (440 nm) and a maximum of 1.0 m-1 for red wavelengths (665 and 694 nm).
Flow cytometry was used to quantify phytoplankton populations. In summer a deep chlorophyll maximum developed at about 80m, characterized by high concentrations of Prochlorococcus, while during the mixing time Eucaryotic, Cyanobacteria and Prochlorococcus were found throughout the water column. During the summer stratification, as a response to the exponential decrease of light in the water column, the phytoplankton showed photoacclimation, evident as a marked increase in cellular chlorophyll with depth.
Since chlorophyll concentrations in the total euphotic zone were low (0.1-0.6 mg/l), their influence on light attenuation was low.
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