Abstract Salinity in the climate sensitive tropical endorheic crater lake Oloidien (Great African Rift Valley, Kenya) decreased from hyposaline to subsaline conditions during the period 2010–2015. The change in salinity was accompanied by a pronounced change in planktonic life forms—from blooms of the cyanobacterium Arthrospira supporting tens of thousands of Lesser Flamingos to highly diverse communities of cyanobacteria and algae which do not sustain the consumer birds. Besides the wel...