Physiological ecology on formation and maintenance of marine forest

最近温暖和营养紧张的海洋状况导致世界许多地区海洋森林的广泛损失。通过培养研究和野外试验，探讨了养分有效性对海洋森林形成和维持的重要意义。在培养研究中，研究了高水温和低营养浓度对岩藻类藻类马尾藻（Sargassum yesoense）和S. confusum生长和存活的联合影响。在5 ~ 30℃条件下，这些低营养浓度的植物生长良好，但在35℃条件下不能存活。我们曾报道过在30℃和低营养浓度条件下，海带Ecklonia cava幼芽孢体在12天内枯萎。这些结果表明，岩藻类与海带相比具有耐高温和耐营养胁迫的能力。在田间试验中，在日本北部北海道西海岸的一处海带床上连续施用液肥，对11月移栽的海带Saccharina japonica与不施肥移栽的海带的生长情况进行比较。施肥的海带生长到1月，未施肥的海带消失。这些结果表明，养分有效性对海洋森林的形成具有重要作用。进一步研究海带和岩藻类的营养需求，对发展海洋施肥造林技术是必要的。

Recent warm and nutrient-stressed oceanographic condition resulted in widespread losses of marine forest in many part of the world. The significance of nutrient availability on formation and maintenance of marine forest was investigated by some culture studies and a field experiment. In the culture studies, the combined effect of high water temperature and low nutrient concentration on growth and survival in fucoid algae Sargassum yesoense and S. confusum was examined. These species in low nutrient concentration grew in 5-30℃, but could not survive in 35℃. We previously reported that the young sporophyte of the kelp Ecklonia cava withered within 12 days in 30℃ and low nutrient concentration. These results suggest that the fucoids have high-temperature and nutient-stressed tolerance compared with the kelp. In the field experiment, liquid fertilizer was continuously provided into a crustose collarine bed in western coast of Hokkaido, nothern Japan, and the growth of the kelp Saccharina japonica transplanted in November was compared with that transplanted to another site without fertilizing. The kelp with fertilizing grew until January, but the kelp without fertilizing disappeared. These results suggest that the nutrient availability has a significant role for the formation of marine forest. Further studies of the nutrient requirement of kelp and fucoids are necessary to develop the marine afforestation technique by fertilizing.