閉鎖循環式水槽におけるアマモZostera marinaの長期育成

抄録

We conducted the experimental long-term cultivation of eelgrass Zostera marina in closed aquarium systems using non-filter and non-exchanging seawater. Eelgrass was cultivated in two types of the closed aquarium systems (2 m³ and 20 m³). The conditions of the cultivation were as follows: water temperature: 15 °C; light source: halogen water lamp; photoperiod: 12-h dark and 12-h light; light intensity (photosynthetic photon flux density, PPFD): 125-200 μmol m^-2 s^-1 in the 2 m³ aquarium and 80-250 μmol m^-2 s^-1 in the 20 m³ aquarium. Dried eelgrass (457g dry weight m^-2) was supplied as fertilizer into the bottom sediments before cultivation experiments. Nutrients seemed to be slowly supplied to eelgrass during the long-term experiment attributed to the slow decomposition of fertilized eelgrass. The growth of eelgrass in the 2 m³ aquarium continued for at least 458 days, a period longer than that of eelgrass in the 20 m³ aquarium (236 days). It indicated that the dry eelgrass buried in the sediment was effective as fertilizer. The experimental eelgrass utilized ammonia the most. Reproductive shoot in the experimental eelgrass appeared from approximately the third month after the transplant, and kept on increasing till the end of the experiment. It indicated that it is possible to conduct a long-term cultivation of eelgrass in a closed system. And the result may contribute to the elucidation of material circulation in seagrass bed.