Samples from two flood plain lakes (Umuorodog-wum I and II) and one permanent natural lake (Oguta) of the lower Niger Delta system (Imo State, Nigeria), representing the outcome of a single sampling campaign in January 1993, are analysed taxonomically. Emphasis is given on the diatom flora but also on some other accompanying algae; a list of 172 algal taxa is currently presented for the area. The relative species abundance patterns and autecology data confirm the frequent occurrence of taxa capable of tolerating the wide environmental fluctuations determined by local conditions of climate and water chemistry. Comparisons are made between the studied lakes including one disturbed site. The results on the water chemistry and biology corroborate findings from similar ecosystems in West Africa.