摘要：Evidence from research in most countries of the world has shown that Cyanobacteria blooms could exhibit acute and chronic toxicity to man and animals alike. Despite the availability of records from other countries of the world, there is no information on the occurrence of these toxins in Northern Nigeria. This study reports the findings of a survey for the occurrence of microcystins in aquatic ecosystems in Zaria Northern Nigeria, using Enzyme Linked Immunosorbent Assay (ELISA) based methods. Five out of the 15 aquatic systems surveyed had microcystins concentrations higher than the acceptable limits (1 μg L-1) for portable drinking water. A total of eight Cyanobacteria species were recorded in this survey namely: Anabaena sp., Microcystis sp., Spirulina sp., Merismopedium sp., Gloetrichia sp., Cylindrospermopsis sp. and Anabaenopsis sp. In all the water bodies surveyed Anabaena sp. and Microcystis sp. had the highest frequency of occurrence and biomass (No. of cells per litre of water).
