Freshwater Red Tide Research Articles

Effect of naturally collected bacteria on growth of Uroglena americana, a freshwater red tide Chrysophyceae.

It was demonstrated that the presence of bacteria was essential for the growth of U. americana, a freshwater red tide Chrysophyceae, in a laboratory culture system. The effect on the algal growth of bacteria collected from Lake Biwa during the bloom was studied. All of the bacteria tested supported the algal growth; and the growth extent of the alga was dependent on the species of associated bacteria. The algal growth was also promoted with the addition of nonsterilized natural lake water. The possible role of bacteria for the algal growth in nature was discussed.

A Freshwater Red Tide on a Water Reservoir

A long-lived, heavy freshwater red tide of Pyridinium occurred in a newly built water supply reservoir, between late February and late May, 1972 and 1973, starting and spreading from the entrance region. The densities of the alga reached at least 9.3 x 104 cells per ml and at least 2, 700 μg chlorophyll- a per liter at a wind drift. The red tide is attributed to the increase of solar radiation, the hardness of water and the sewage drains from towns and croplands. The water mass containing a dense algal bloom was an excellent receiver of the solar radiation. This flagellate acted as an accumulater of nutrients at the entrance region of the reservoir.