Undaria pinnatifida Habitat Loss in Relation to Sea Urchin Grazing and Water Flow Conditions, and Their Restoration Effort in Ogatsu Bay, Japan
スポンサーリンク
概要
- 論文の詳細を見る
This study investigated the mechanism of the loss of Undaria pinnatifida beds in Ogatsu Bay, Japan. Wave heights at the outside of the bay were 1 to 2 m over the course of study. In the outer areas of the bay with high water velocities, more than 14.5 ± 3.4 cm sec -1, U. pinnatifida grew densely and sea urchins were scarce. However, in some outer areas with lower velocities, less than 7.8 ± 2.3 cm sec -1, U. pinnatifida grew sparsely where the aggregation of sea urchin was found. In contrast, in the inner areas of the bay with calm water having velocities of 2.4 to 4.6 cm sec-1, the density of sea urchin was high and the U. pinnatifida beds disappeared. These results indicated high water velocities in the outer bay areas prevent the grazing by sea urchins. Disappearance of U. pinnatifida in the inner bay areas seemed to be caused by the high grazing pressure of sea urchins in calm water velocity conditions.We also performed a U. pinnatifida restoration effort to reduce the effects of the grazing pressure by sea urchins in the barren grounds in the inner areas of the bay. Artificial buoyed reefs were designed to prevent the migration of sea urchins by being detached from the bottom and allowed the recovery of U. pinnatifida and other non-encrusting macroalgae. Although there were some losses of transplanted U. pinnatifida partly caused by the withering after the reproductive maturation period, Saccharina japonica and other macroalgae were naturally recruited and increased due to the inhibition of migration by sea urchins using the buoyed reefs. In contrast, the formation of barren community remained at the area grounded to the bottom allowing the migration of urchin in the inner bay. Overall, our restoration efforts using the artificial buoyed reef, although not ideal, resulted in the success of the recovery of macrolagal habitats in the sea urchin - dominated barren grounds by the reduction of grazing pressure of sea urchins.
論文 | ランダム
- 焦点は「永世中立とのかねあい」--国連加盟に動き出したスイス(特派員ノ-ト)
- 遭難続出日本人のアルプス登山--事故起こすガイドなしパ-ティ-(特派員ノ-ト)
- カネかけず実質的に--欧州バカンス今年の傾向(特派員ノ-ト)
- スイス イメ-ジ壊す現実も (海外生活の悲喜劇(特派員ルポ))
- 保守的な社会に不満ぶつける--スイスで年中行事化した若者のデモ騒ぎ(特派員ノ-ト)