河口干潟における底生動物と有機物分解活性

抄録

TOMINAGA, Akira and Yasushi KURIHARA (Biological Institute, Faculty of Science, Tohoku University). 1987. Study on the microbial organic decomposition in the tidal flat at river mouth with reference to the occurrence of benthic invertebrate animals. Benthos Research (Bull. Jap. Assoc. benthology), 32 : 1-11.
The microbial activities for decomposition of organic matters in the river mouth were highest in mud of the tidal flat, but low in the brackish reed marsh and bottom mud of the riverbank which was always submerged in the water. The C/N ratio in the tidal flat was lower than those in the riverbank bottom mud and brackish reed marsh, indicating that the quality of sedimentary organic matters in the tidal flat was different from the other places.
Surface of the bottom mud in the tidal flat, on the other hand, is covered sometimes with microalgal mat including Euglena as the dominant species. Therefore, a black box (2.5 x 2.5 x 1.0 m) was installed on a part of the tidal flat in order to avoid the effects of algal mat on the activities of microbial decomposition and benthic animals, and the microbial activities for decomposition of organic matters and the fauna of benthic animals in the darkened condition were compared with the control. No differences were found on the organic matters-decomposing activities between the darkened and control conditions, except for denitrification. In the darkened condition, compared to the control, the denitrification activity was obviously high and the benthic animals including polychaetes were found also in high numbers of individuals. These results indicated that the organic matters-decomposing activities excepting the denitrification were not affected by the benthic animals and microalgal mat and the denitrification activity was enhanced by the presence of polychaetes.