Figure 3.

Parameters sampled from the surface and bottom layers, along the eutrophic gradient; from Qishon estuary system (E3 to E1) to the coastal reference station (Sh). Water samples were analyzed for; Chlorophyll a as phytoplankton proxy (A), TEP concentrations (B), Microscopic visualization of a representative bio-aggregate (C), heterotrophic bacterial abundance (D), bacterial production (E), and β-glucosidase activity (F). Bars represent the average of three independent sampling dates with corresponding standard deviation. To visualize bio-aggregates water were sampled from a representative station (E1). Bacterial clusters were stained with SYTO 9 (bright green) and captured with epifluorescent microscopy. Bright field microscopy was used to visualize transparent exopolymers particles (TEP) stained with alcian blue (as light blue), and algal cells (as dark green). Images were superimposed using Image J software (http://rsbweb.nih.gov). Chlorophyll a pigment was not detected by autoflorescence within the bacterial clusters.