MATERIALS AND METHODS

Water samples for TEP analysis were monthly collected at DYFAMED site, using 30 liters Niskin bottle at the depth of chlorophyll maximum (DCM) layer previously determined by a fluorimeter coupled on a CTD "Seabird" (SBE 25) probe. All samples for TEP were prepared fresh, on board, within 2 hours following the samplings. 
TEP were studied following the method of Passow et al. (1994). Several seawater aliquots (5ml, 10ml, and 15ml) were gently filtered through 0,2 (m Nuclepore( filters under a constant and low pressure. TEP retained on the filter were stained with 500 (l of a solution of 0.06% acetic acid (pH 2.5) and 0.02% Alcian blue 8GX (Hopkin & William, Chadwell Health, England). After the staining procedure, TEP was transferred to a microscope slide using "Filter-Transfer-Freeze" technique (Hewes & Holm-Hansen 1983). 
TEP were observed through an Axiophot-Zeiss microscope. Pictures were captured with a CCD colour video camera (COHU 2252-1040, 752x582 pixels resolution, 0.08 lux minimum sensitivity). TEP were counted using Image Pro Plus 4 software. A minimum of 200 TEP were counted and sized at 3 successive magnifications (125x, 250x, 500x, i.e. a total of 600 TEP), in order to better cover the entire size spectra (Mari & Burd 1998). The equivalent spherical diameter (ESD) of each TEP was calculated from measurement of its cross-sectional area by mean of a semi-automatic image-analysis system. Counts were classified according to their ESD into logarithmic size classes between 1 and 100 (m. 
The number of TEP per ml were normalised by the length of the considered size class (µm). TEP volume concentration corresponds to volume of TEP per ml normalised by the length of the considered size class (µm). 

References
Hewes CD, Holm-Hansen O (1983) A method for recovering nanoplankton from filters for identification with the microscope: The filter-transfer-freeze (FTF) tecnhique. Limnol Oceanogr 28 (2) : 389-394
Mari X, Burd A (1998) Seasonal size spectra of transparent exopolymeric particles (TEP) in a coastal sea and comparison with those predicted using coagulation theory. Mar Ecol Prog Ser 163 : 63-76
Passow U, Alldredge AL (1994) Distribution, size and bacterial colonization of transparent exopolymer particles (TEP) in the ocean. Mar Ecol Prog Ser 113 : 185-198

Materials and Methods

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