The organic water pollution of streams and lakes has been usually discussed from the different view point, i.e. in running waters it has been discussed from the view point of saprobic system, in standing waters from that of trophic system, as is generally known.
Such the difference in measure to determine the degree of water pollution between the two make the composite discussion difficult.
Recently, a numerical index to organic pollution of running waters (Diatom Assemblage Index -DAI
po) has been developped based on epilithic diatom assemblages.
In this research, the applicability of DAI
po to pollution of standing waters was investigated using 100 attached algal community samples collected from dammed lakes, irrigation ponds and fish culture ponds, and 246 diatom taxa occurred at 100 sampling sites were able to be classified into three ecological groups, Saprophilous, Eurysaprobic and Saproxenous based on their tolerance index without a considerable alternation in the ecological group to which the taxon belongs, compared with the former result obtained from running waters.
In attached diatom assemblages of standing waters, relative abundance of taxa belonging to each ecological group varies in proportion to increase of DAI
po value in the same manner as shown in running waters.
From the facts, we may conclude that DAI
po is useful not only to running waters, but also to standing waters, as a common index to organic pollution degree.
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