枸杞岛铜藻空间分布格局初探

Spatial distribution pattern of Sargassum horneri around Gouqi Island,Shengsi,China

为了查清铜藻空间分布格局与影响因子之间的关系,采用水下采样方法对不同生境条件下铜藻分布和生长情况进行了调查,并从大小两个尺度(站点间和站点内)分析了铜藻空间分布与影响因子之间的关系。结果发现,在站点尺度上,铜藻多集中分布于隐蔽的内湾处,分布密度和株高显著高于暴波站点(P<0.05),暴波站点的波浪和水流运动大小以及浊度显著高于隐蔽站点(P<0.05),说明暴波强度是影响铜藻水平分布和生长的主要因子之一;在站点内,铜藻垂直分布特征明显,潮间带低潮区铜藻分布密度和株高显著高于潮下带(P<0.05),且分布在潮间带低潮区的藻苗平均株高最高;铜藻分布密度和株高与附着基粗糙度、坡度、坡向表现出一定的相关性,但经相关性分析表明,水深与铜藻分布密度最相关(r=-0.337,P=0.001),粗糙度次之(r=0.175,P=0.092),与坡度和坡向相关性不高,说明了与水深相关的光照条件可能是影响铜藻垂直分布和生长的另一个主要因子。研究表明,附着基物理特征不是影响铜藻分布的主导因子,由波浪和水流运动引起的沉积物再悬浮影响到铜藻所需的光照条件,进而影响到铜藻的分布与生长,以此推断出沉积物可能是影响铜藻空间分布格局的主导因子。

This research surveys distribution and growing state of Sargassum horneri in different habitats by using underwater quadrat sampling method,and also studies the relationship,in both large and small scales（among sites and inside site）,between the spatial distribution of S.horneri and influencing factors,thus provides references to protect and recover seaweed field.It has been found that among sites,many of S.horneri grow in sheltered bay,where plant distribution density and plant length are obviously higher than those in stations of wave exposure（P0.05）,while wave,water motion,and turbidity in sites of wave exposure are inversely more remarkable than those in sheltered sites（P0.05）,which suggests that water motion becomes a limiting factor on the horizontal distribution and growing of S.horneri.Within site,the vertical distribution of S.horneri has distinctive characteristics.Distribution density and plant length of S.horneri at the bottom of intertidal zone are obviously higher than those in subtidal zone（P0.05）.Study result also shows that,in small scale,the distribution density and plant length of S.horneri have some degree of correlation with the roughness,slope gradient and slope aspect of attachment substances.However,correlation analysis manifests that water depth has the highest correlation with the distribution density and plant length of S.horneri（r=-0.337,P=0.001）,and roughness has the second highest correlation（r=0.175,P=0.092）,while slope gradient and slope aspect merely have small correlation.So,it indicates that light condition maybe becomes the other limiting factor on the vertical distribution and growth of S.horneri.Study finally finds that physical characters of attachment substances are not the vital factors in affecting the distribution of S.horneri.We can infer that sediment is the key factor in affecting spatial distribution pattern of S.horneri,as a result of wave and water motion which cause resuspension of sediment to influence the light condition which S.horneri needs.