The ecology of ciliated protozoa in an alkaline-saline lake, lake Nakuru, Kenya

Abstract

Abundance, biomass and production of planktonic ciliates in Lake Nakuru were estimated between June, 1993 to January, 1994. Lake Nakuru had high abundances of a cyanobacterium (Spirulina platensisy, flagellates, algae and bacteria (1.98x1<1 cells. ml"), which provided food for ciliates and other consumers. Small ciliates with < 50 Jtm ESD (e.g., Cyclidium) accounted for 78% of total ciliate abundance and were bacterivores while large ones (> 100 Jtm ESD) were omnivores (e.g., Frontonia) or fed on bacteria, flagellates and diatoms '(e.g., Paramecium). Other ciliates were carnivores (e.g., Sphaerophrya). Rotifers were predators of ciliates, but some ciliates fed on rotifers. Ciliate abundances. ranged from l.04xHf to 1.42x107 cells.l' (mean 1.15x106 cells.l"). Ciliate biomass ranged from 1.69x107 to 5.0xlO11 pgc.r' (mean 1.82xlOlo pgC.l-1) and mean production was 6.44xl<1- pgC.l-1.d-l. The variation of ciliate abundance, biomass and production with month-site, chlorophyll a, bacterial numbers, rotifer abundance, arid physico-chemical variables is discussed