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サンゴ幼生の着床を目的としたモルタル製着床具の開発

片倉 徳男^＊１・高山 百合子^＊１・古田 敦史^＊２

亜熱帯海域において重要な生態系を形成するサンゴは，オニヒトデ等による食害，異常な高水温，沿岸域の開発行為等による枯死に伴う現存量の減少が問題となっている。いくつかの移植方法が開発され，この一つに有性生殖法がある。有性生殖法ではサンゴの幼生を付着させる着床具が必要だが，現在，用いられている着床具はいずれもセラミックス製である。そこで有性生殖法を広めるために容易に調達が可能なモルタル製の着床具を開発し，その実用性を評価した。開発した着床具をサンゴ幼生の発生が見込まれる亜熱帯海域に設置し，着床するサンゴ幼生の量を評価した。600個の着床具を亜熱帯海域の沿岸域に設置し設置から約8か月後に，120個を回収した。この結果，23個の稚サンゴの着床を確認し，開発した着床具の有効性を実証した。今後は稚サンゴを安定した基盤に再移植し，移設先での成長速度の評価を実施する予定である。

＊１ 技術センター 土木技術研究所 水域・環境研究室
＊２ 技術センター 知的財産部 特許室

Development of New Artificial Coral Settlement Device for The Implantation of Coral Larvae

Norio KATAKURA^*1, Yuriko TAKAYAMA^*1 and Atsushi FURUTA^*2

The coral reef is important ecosystem of the subtropical sea area. However, the coral reef is decreasing by feeding damage due to the acanthaster, abnormal high water temperature and human development activity. Some methods to restore the coral were developed. One is coral sexual reproduction. An artificial coral settlement device is necessary for the coral sexual reproduction. Most of artificial coral settlement device are made in ceramics. But in the case of ceramics, manufacturing facility is limited. The materials without a restriction in terms of manufacturing are necessary to popularize the coral sexual reproduction. Therefore a new artificial coral settlement device made in mortar was developed. The procurement of mortar is easier than ceramics. This new coral settlement device has the prevailability that is higher than the conventional coral settlement device. 600 of coral settlement devices were installed in the subtropical sea area and evaluated the settlement coral larvae. 120 pieces of coral settlement devices were picked up after eight month. As a result, 23 coral larvae were observed. This result shows the basic performance of new artificial coral settlement device. New artificial settlement device which are growing of coral will transplant to the stable base in future. And a growth rate of the coral is evaluated.