Physiological ecology on formation and maintenance of marine forest

最近温暖和营养紧张的海洋条件导致世界许多地区的海洋森林普遍丧失。通过一些养殖研究和野外试验，探讨了养分有效性在海洋森林形成和维持中的意义。在培养研究中，研究了高水温和低营养浓度对岩藻马尾藻和马尾藻生长和存活的影响。这些物种在低营养浓度下能在5-30℃内生长，但不能在35℃内存活。我们以前报道过，在30℃和低营养浓度的条件下，海带的幼孢子体在12天内枯萎。这些结果表明，与海带相比，岩藻具有较高的高温和营养胁迫耐受性。在大田试验中，在日本北部北海道西海岸的结壳床上连续供应液体肥料，并将11月份移栽的海带与不施肥的海带的生长情况进行了比较。施肥的海带一直生长到1月份，但没有施肥的海带消失了。这些结果表明，养分的有效性对海洋森林的形成具有重要的作用。进一步研究海带和岩藻的营养需求是发展海洋施肥造林技术的需要。

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.