魚類養殖場直下に堆積したヘドロ(有機汚泥)のイトゴカイによる浄化の試み

概要

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We have attempted to promote the decomposition of organic matter deposited on the marine bottom below fish net pen culture by the biological activities of a deposit feeding capitellid polychaete, Capitella sp. 1. The organically enriched sediment was reproduced in the tub in the laboratory by the addition of moist pellets for fish culture on the sediment. We compared the chemical characteristics of the sediments between the experiments with and without Capitella. In these experiments, the Capitella colonies increased rapidly, and the biological activities such as feeding, reworking etc. efficiently decomposed the organic matter added on the sediment. The levels of organic matter of the sediment with Capitella fluctuated stably around the initial level throughout the period of the experiments for 60 days, while the levels in the experiments without Capitella gradually increased. The promotion of organic decomposition of the sediment in the experiments with Capitella also prevented the development of reduced conditions in the sediment. If we can re-establish a dense Capitella population on the bottom below the fish net pen quickly in the environmental recovery process from autumn to winter by releasing artificially cultured colonies of the worms, the potential of organic decomposition on the bottom will be significantly enhanced.