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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 3085

Sudo Ryuichi, Ohtake Hisao, Aiba Shuichi, and Mori Tadahiro; Some ecological observation on the Decomposition of periphytic Algae and Aquatic plants. Water Research 12:179-184, 1978

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Stigeoclonium tenue, Chlamydomonas sp. and Chlorella sp., which are dominant periphytic algae in a shallow river (Tama-gawa, running through the Metropolitan area of Tokyo) were subjected to dark- and aerobic-decomposition test using Selenastrum capricornutum as control. The decomposition of aquatic plants, Potamogeton crispus and Potamogeton pusillus which become dominant in the river mid- and downstream during summer was also studied. Successions of protozoa and smaller metazoa were noted from the decomposition tests. Regardless of the species of algae and aquatic plants studied the decomposition rate could be simulated as the 1st-order reaction if the refratory fraction, f of each organism was used as the datum of assessment. The value of f was rougly from 0.2 to 0.4, also irrespective of the organism examined. The rate constat, k thus assessed extended from 0.08 to 0.2 day-1 at 20 degrees C. Phosphorus and nitrogenous compounds regenerated into liquid (decomposer) amounted at 50th day of decomposition test to a level of 50 to 75% of that retained initially with the cells. Thus far, the seriousness of secondary pollution due to decomposition of periphytic algae and aquatic plants was pointed out. Lastly, the significance of removing nutrients from effluent of the wasterwater treament was demonstrated.