Algal Esterase Activity as a Bioindicator of Environmental Degradation in a Freshwater Creek

Activity of esterase in response to exposure to acid mine drainage, sewage, and elevated conductivity from dry land salinity was investigated in two species of algae found in a stream in Australia. The ability of the algal esterases to convert fluorescein diacetate to fluorescein, was measured by measuring the fluorescence of individual cells. One hour of exposure to acid mine drainage increased the percentage of cells in the low esterase activity state by between 60 and 90%. This decreased esterase activity lasted 24 hours. When cells were exposed to highly conductive water for one hour, similar declines in esterase activity were found, but the effects were only temporary. Exposure to sewage of the green algae significantly reduced conversion of fluorescein diacetate to fluorescein after 24 hr. For determination of acid mine drainage, a culture of the blue green algae exposed to water samples for 24 hours was the most sensitive. The bioassay was capable of distinguishing among the pollutants