Title Techniques for the restoration of Sargassum beds on barren grounds
Authers Kousuke YATSUYA
Keywords Sargassum, drifting seaweed, seaweed aquaculture, seedling production, trap
Citation Bull. Fish. Res. Agen. No.32, 69-73, 2010
Abstract
On barren grounds formed after deforestation, supply of propagules is often limited due to the long distance from existing seaweed beds. However, drifting thalli of Sargassum can reproduce and introduce embryos even on barren grounds. In order to investigate whether drifting Sargassum can effectively supply embryos, the abundance and fecundity were investigated in thalli entangled around floating ropes of a set net in western Wakasa Bay, in the Sea of Japan. Biomass of the entangled drifting Sargassum was the highest in late May. Drifting thalli of Sargassum patens and S. macrocarpum were found to release comparable numbers of embryos to those growing in seaweed beds. The following year, an artificial reef was deployed in the same area, and floating ropes were installed above the artificial reef to entrap drifting Sargassum. Six month later, the percent cover of Sargassum on the top of the artificial reef was higher around the floating ropes, suggesting that this setup facilitated the effective supply of Sargassum embryos. In addition, novel techniques to culture Sargassum seedlings were developed. The seedlings can be cultured freely in a transparent aquarium with strong bubbling. It is easy to adjust the density of seedlings in accordance with their size, avoiding density-dependent mortality and growth suppression. We also developed two techniques to fix seedlings to some setups or to the seabed. These techniques using seedling production and aquaculture can be applied for the recovery of Sargassum beds on barren grounds.
URI http://www.fra.affrc.go.jp/bulletin/bull/bull32/69-73.pdf