Geosmin Production by Cyanobacteria (Blue‐green Algae) in Fish Ponds at Auburn, Alabama

Abstract Studies on production of geosmin, the compound responsible for earthy‐muddy flavor in water and fish, were carried out at the Auburn University Fisheries Research Station. Water was collected from ponds during 44 cyanobacterial bloom periods from April to September. Geosmin (trans‐1, 10‐dimethyl‐trans‐9‐decalol) was detected at levels averaging 4.77 μg/L when Anabaena species with straight trichomes were predominant. Lower geosmin concentrations were associated with blooms of Anabaena species with coiled trichomes, Microcystis aeruginosa, and Aphanizomenon flos‐aquae, and averaged 0.24, 0.12, and 0.07 μg/L, respectively. Study of four Anabaena blooms over a period of 4–8 weeks showed that changes in geosmin were correlated significantly with changes in trichome abundance. Geosmin disappeared from the water in seven days when Anabaena died. Comparison of geosmin concentrations in raw and filtered water showed that, on average, 90% of the geosmin could be associated with the particulate fraction. Dissolved geosmin concentrations ranged from 0.07–0.85 μg/L.