Toxin-producing blooms of the cyanobacterium Microcystis aeruginosa in rainwater ponds in Saudi Arabia

The present study describes for the first time the toxin production by Microcystis aeruginosa blooms in three rainwater ponds in Saudi Arabia. The cell density of M. aeruginosa correlated with chlorophyll-a, temperature and nutrient concentrations. Microcystis blooms produced the hepatotoxin microcystin (MCYST) with concentrations of 0.988-3.04 mg g^-1 dry weight, and a toxin profile consisting mainly of MCYST-RR, -YR and -LR. MCYSTs were also detected in pond waters at levels exceeding the WHO guideline value (11.2-34.6 μg l^-1). The study suggests the monitoring of toxic cyanobacteria in such potable water sources to protect the public from potent toxins.