有機物負荷に対するマイクロコズムの応答

抄録

Experiments to see the relationship between the community responses to organic loading and successional age of the community were performed in aquatic microcosms consisting of bacteria, Chlorella, blue-green alga, ciliate protozoa, rotifer and aquatic oligochaete. Invertebrates in the microcosm declined to extinction when organic loading was added at a young stage, while invertebrates in the mature stage hardly became extinct after loading. Algae in the sediment, which increased as succession proceeded, contributed to the stabilization of invertebrate populations. Invertebrates in the microcosms loaded at a young stage were found to be extinct by a temporary rise of the un-ionized ammonia concentration, which was caused by the accumulation of total ammonia (due to the small amount of algae in the sediment) and by high pH. On the other hand, the mature microcosm showed high stability because a large amount of algae and low pH inhibited the increase of un-ionized ammonia subsequent to loading.