In order to meet the need of increasing yield and reasonable management of marine resources, artificial mass production of aquatic seeds and saplings are required. Accordingly, a great number of microalgae are required to be supplied stably to the seeds and saplings concerned. An experimental facility was developed for achieving a high-density cultivation of microalgae as feed for the seeds and saplings in early growth stages of bivalves, echinoderms and crustaceans. The experimental facility developed an optical radiant environment with culture-solution tank (capacity: 200 l) covered entirely with luminaries, which were composed of compactly single-capped three-band fluorescent lamps 55 W controlled by a dimmer. This set-up was able to produce a high lighting efficiency and a high uniformity ratio of photosynthetic photon flux density (PPFD, more than 300 μmol m^-2s^-1). The facility also had a water-bath to keep culture-solution at a constant temperature and an aeration control for aerating solution, as well as for washing and sterilizing tank based on high work efficiency. This experimental facility could readily become a practical way of achieving a stable supply of microalgae needed for the management of marine resources.

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Pond bottom sediment had been used extensively as a soil dressing on farms until a substitution of chemical fertilizer has been widespread since the world war II. However, recently, pond bottom sediment is hardly utilized as fertilizer. As the result, deterioration of water quality and decrease of reservoir volume have been caused by the excessive sedimentation of pond bottom sediment. The authors propose that pond bottom sediment is utilized as a replanting basis. A replanting basis is made from burning the pond bottom sediment by a high temperature. The physical property of the soil was compared with the burnt product and general replanting basis (Kanuma soil and Akadama soil, etc.) in order to examine the application of the replanting basis. As the result, it was proven that the physical property of the burn product changed into the equivalent one of the general replanting basis. Then, the pot test was carried out in the bermuda-grass using the burnt product. As a result of the pot test, it has been promoted the growth of the bermuda-grass and it has been excelled in the superiority of the utilization as a replanting basis.

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Closed habitation experiments are to be carried out using Closed Ecosystem Experiment Facilities (CEEF) from 2005 to 2009. Three and six one-week habitations are to be conducted in 2005 and 2006, respectively. The duration of the habitation is to be elongated to two and four months in 2007 and 2009, respectively. Preliminary study and testing have been conducted in order to start the closed habitation experiments. In 2004 as the last year of the preliminary test phase for the 2005-2009 experiments, periodical harvesting from staggered cultivation of 23 crops including rice, soybean, peanut, and sugar beet was continued during 103 days. In order to balance with metabolisms of humans and animals, it is necessary to stabilize production of edible and inedible biomass, CO₂ uptake and O₂ production of crops. Although biomass production decreased rapidly during the first five weeks of the 103-days, it was relatively stable during the last ten weeks. Average major foodstuffs in the harvested edible biomass met the requirement of two habitants (named as eco-nauts) although several minor ingredients were insufficient. CO₂ uptake and O₂ production of the crops (150 m²) were determined to be 99.9 mol day^-1 and 104.8 mol day^-1, respectively, based on biomass and ingredient analysis. Total CO₂ and O₂ exchanges of two Shiba goats and two eco-nauts were 63 and 66% of those of the crops, respectively. Flows of carbon and oxygen in the material circulation system including crops, eco-nauts, Shiba goats and physical/chemical part were calculated using these data. The analysis showed that waste processing systems of Closed Plant Experiment Facility and Closed Animal and Habitation Experiment Facility (CAHEF) will proceed solid waste of 307 g day^-1 (10.8 mol C day^-1) and 651 g day^-1 (25.8 mol C day^-1), respectively, and that the CO₂ separator of the CAHEF will separate 89.1 mol CO₂ day^-1. The result obtained in this study confirmed that the crops would serve sufficient biomass and O₂ to eco-nauts and Shiba goats in habitation experiments. CO₂ expired by eco-nauts and Shiba goats also will be served to the crops. However, it will be later than 2008 that all of the CO₂ produced by waste processing returns to the crops, because the completion of integration of waste decomposition systems of the CEEF is planned in 2007. A part of CO₂ will be served from outer source to compensate the lack of CO₂ from the waste processing, and surplus O₂ will be released because of lack of O₂ consumption by the waste processing, by 2007. A result of a rough estimation of water flow in the CEEF conducted based on preliminary experimental data was also shown.

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