Palaeoecological reconstruction of the late Oligocene Maar Lake of Enspel, Germany using lacustrine organic walled algae

Abstract

The fine laminated black pelites of fossil Lake Enspel (Upper Oligocene, Westerwald, W-Germany) have been analysed using palynological methods. With the help of lacustrine organic walled algae it was possible to reconstruct some aspects of the ecology of the palaeolake. Two organic walled primary producers have been recognized (Botryococcus and the freshwater dinoflagellate Cleistosphaeridium lacustre). During holomictic periods of the lake, freshwater dinoflagellates and Botryococcus coexisted. In more meromictic phases, however, Botryococcus and Cleistosphaeridium lacustre act as competitors. During times of oligotrophic and acidic water conditions with less or nearly no nutrient input into the lake, Botryococcus was prevailing. In times with more eutrophic and alkaline water chemistry caused by increasing nutrient input into the palaeolake, Cleistosphaeridium lacustre was predominant. Subordinate algal cysts of Zygnemataceae together with pollen of shore plants (Typha, Sparganium) indicate areas of shallow water or even a swampy shoreland of unknown size around Lake Enspel during some time periods.