Stratigraphy of specific algal and bacterial carotenoids in the sediments of Lake Varese (N. Italy)

A study on the succession of some phytoplankton populations in the very eutrophic Lake Varese over the past 80–100 years, was based on thin-layer chromatography of four group-specific carotenoids (echinenone, lutein, myxoxanthophyll and oscillaxanthin). The development of diatoms was traced by microscope counts of their frustules. In addition, the carotenoid okenone, peculiar to some Chromatium species, was identified and related to lake trophic conditions (the Chromatium species are obligate anaerobic bacteria, and use H₂S).