Seston and organic matter

Abstract

Studies carried out during 2000–2010 allowed us to estimate the temporal and spatial dynamics of structural and functional characteristics of seston and organic matter in Lake Kinneret: seston mass (total suspended solids, TSS), and particulate, 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 longterm stability of seston dynamics.