ACCUMULATION OF FRESH-WATER RED TIDE IN A DAM-RESERVOIR

The distribution and biomass of Peridinium bipes f. occultatum were ob served in the autumns of 1991, 1992 and 1994 at the head of the Shoren ji Dam reservoir (Mie prefecture, Japan). Summarizing observations and some other information, we discussed processes related to the accumul ation of Peridinium biomass. In the study area, biomass of Peridinium increased at a similar rate to growth day by day, and roughly 2/3 of t he daily maximum biomass fluctuated in a given day. The horizontal 'im port' and 'export' of Peridinium biomass by flows mainly change the bi omass of red tide at the upstream end of the reservoir. Flow control i n the reservoir, as well as growth control, will also be important in suppressing freshwater red tide. (C) 1998 IAWQ. Published by Elsevier Science Ltd.