473 Chapter 26 Seston and Organic Matter Arkadi Parparov, Tamar Zohary, Tom Berman and Gideon Gal T. Zohary et al. (eds.), Lake Kinneret, Ecology and Management, Aquatic Ecology Series 6, DOI 10.1007/978-94-017-8944-8_26, © Springer Science+Business Media Dordrecht 2014 A. Parparov () · T. Zohary · T. Berman · G. Gal The Yigal Allon Kinneret Limnological Laboratory, Israel Oceanographic & Limnological Research, P.O. Box 447, 14950, Migdal, Israel e-mail: parpar@ocean.org.il T. Zohary e-mail: tamarz@ocean.org.il G. Gal e-mail: gal@ocean.org.il Abstract Studies carried out during 2000–2010 allowed us to estimate the tempo- ral and spatial dynamics of structural and functional characteristics of seston and organic matter in Lake Kinneret: seston mass (total suspended solids, TSS), and par- ticulate, dissolved, and total organic carbon (POC, DOC, and TOC = POC + DOC). Similar characteristics were determined for the Jordan River. On average, TSS, POC, DOC/POC, and TOC declined with water depth, indicating relative increase of seston decomposition. Phytoplankton was the largest component of the living part of seston in Lake Kinneret, comprising on average 24.7 % of the seston dry weight. During intense dinoflagellate blooms, phytoplankton comprised up to 90 % of the seston mass. Despite significant variability of the living compartments and drastic changes in the phytoplankton structure, the nonliving component was, on average, the largest component of Lake Kinneret seston, comprising about 60 % of seston mass. Metabolic activity associated with seston dominated by specific algal taxa was also estimated. The potential ecosystem importance of transparent exopolymer particles (TEP), a previously unrecognized, major component of the seston, is described. Major fluxes within the seston cycle were estimated directly, allowing the compilation of a seston budget. Sources and sinks of seston appeared to be approximately balanced which is in good agreement with the observed long- term stability of seston dynamics. Keywords Organic carbon · Total suspended solids · Seston · Community respiration