ウニ侵入防止フェンス内におけるホソメコンブ群落に適する底面波浪平均流速とウニ類除去時期

抄録

The investigation was conducted in 'Isoyake area' Oshoro Bay, Otaru City, Hokkaido, during October 1999 to April 2000. Four experimental sites were established to observe the efficiency of benthic velocity for afforestation of the kelp bed. All sites were enclosed by fence to control the grazing pressure of the sea urchin. Biomass of the kelp increased with the mean benthic velocity while angulations and corrugation decreased with the velocity. For the afforestation of the kelp, it was prefer the yelocity was more than about 0.3m/s. To examine the optimum timing of fence establishment, settlement of zoospore and survival of gametophyte of the kelp were investigated. New substratum was embedded regularly at inside of the fence. Monthly collection was carried out both of stomach contents of the sea urchin and natural substratum at outside of the fence. The contents and the substratum were cultured under laboratory condition. Occurrence of the kelp was restricted to the new substratum, which was embedded before early November, the stomach contents, which were collected before early December, and the natural substratum, which was collected before middle December. For afforestation of the kelp, we should remove the sea urchin before early November.