渔山列岛海藻场空间分布格局及成因分析

Spatial Distribution Pattern of Seaweed Bed and Its Relationship with Environmental Factors around Yushan Archipelago

为探明渔山列岛海域海藻场的空间分布格局,解析海藻场退化机制,提出海藻场生态修复策略,于2015年6月,采用水下样方法对北渔山岛海藻场的分布特征进行了调查,并比较分析了海藻场在水平和垂直分布上的差异。研究结果显示:(1)北渔山岛海藻场的支撑物种为瓦氏马尾藻和铜藻,且瓦氏马尾藻的平均密度达到了250 ind/m^2,远高于铜藻的密度,是海藻场中的优势种,反映了渔山列岛的生态保护效果较好,瓦氏马尾藻海藻场生态系统相对稳定。(2)在水平分布上,瓦氏马尾藻在岛礁东南向分布稀少、而在西北向分布密集,这与岛礁不同方位受风浪影响的强度有关;在垂直分布上,瓦氏马尾藻垂直分布范围较宽,且最大分布水深为6.35 m,这也是在我国瓦氏马尾藻目前记录到的最大分布水深,而2~4 m的水深范围成为瓦氏马尾藻最适宜的栖息水深,但平均株高仅0.38 m,且生物量较低,说明近岸岛礁海域的瓦氏马尾藻藻场也处于濒临灭绝的边缘。研究结果表明,多年生瓦氏马尾藻的营养繁殖方式比一年生铜藻的有性繁殖方式更能适应现今的海洋生态环境,而一旦瓦氏马尾藻资源在外界干扰下受损将很难恢复,因此,我们可通过人工移植多年生瓦氏马尾藻的方法修复近岸海域的海藻场资源。

In order to find out the spatial distribution pattern of seaweed bed, and analytic degradation mechanism of seaweed bed, and put forward ecological restoration strategy of seaweed bed, we investigated the distribution of seaweed bed around Yushan Archipelago in the East China Sea, and trying to figure out the distribution of different macroalgae. Our result showed that：（ l ） Sargassum vachellianum and S. horneri were the main species in Norh Yushan Island seaweed bed. Moreever, the average density of S. vachellianum reached to 250 ind/m2, which was much higher than S. horneri. So S. vachellianum became the dominant species, which suggested that the environment here was good and the seaweed bed of S. vachellianum had a stable ecosystem.（2） On the horizontal distribution, the density of S. vachellianum was at i t ＇s highest in Northwest and lowest at Southeast, which was related to the exposure wave; on the vertical distribution, S. vachellianum, had a wider depth range, and the depth was as deep as 6.35 m, which was also the recorded maximal depth up to now in China. And at the depth of 2-4 m, S. vachellianum, had the best suitable habitat, but the average length of S. vachellianum at this depth was 0.38 m, and the biomass was low, which suggested that S. vachellianum, was on the brink of extinction. These findings implied that perennial S. vachellianum^ vegetative propagation, was more adaptable to present marine ecological environment than annual S. horneri sexual propagation. But S. vachel-lianum was hard to restore once externally disturbed. Therefore, we can restore S. vachellianum on the nearshore seaweed bed by artificially transplanting.