Paleoenvironmental studies undertaken in the past few years on lacustrine sediments indicate highly complex organic records. Indeed, the organic sources in lacustrine environments are numerous and early diagenetic transformations further complicate the molecular signal. This diagenetic filter can sometimes mask environmental information (by degradation of organic source biomarkers) as well as revealing it by purification of the signal (information on condition of sedimentary organic matter (SOM) incorporation). The preliminary calibration between primary producers and organic matter in sediments is essential in order to understand the processes prevailing in deposition and preservation of sedimentary organic material.