硇洲岛海域文昌鱼的分布与栖息地底质关系

Relation of Branchiostoma belcheri distribution to the sediments in waters near Naozhou Island

为研究清楚南海硇洲岛海域文昌鱼分布的底质环境条件,利用2006年7月～12月3个季度采集的硇洲岛海域沉积物样品,进行8种孔径的套筛分选,取得不同粒径颗粒的百分比数据.运用沉积物的各种参数,结合文昌鱼的分布数据进行分析,发现硇洲岛海域文昌鱼适宜栖息底质类型为细中砂、中砂和粗中砂.中值粒径MDΦ0.547～2.745φ;四分位离差QDΦ0.536～0.980;四分位偏态SKΦ-0.147～0.101;众值粒径MoΦ0.731～3.152.φ0.2～0.85mm粒级颗粒所占比例≥58%时,文昌鱼密度显著地高.聚类分析和回归分析发现0.2～0.85mm粒级含量和文昌鱼分布密度具有明显的相关性.对比各地文昌鱼栖息底质发现,砂质结构基本一致,但具体类型存在地域差异.

Branchiostoma belcheni and sediment samples were collected in waters near Naozhou Island in South China Sea during a survey from July to December in 2006. Sediment samples were classified with sieves of 8 different mesh sizes, respectively. Percentages of sand granularities were calculated for the sediments. Distributions of Branchiostoma belcheni in relation to sediments was analyzed. It showed that the most proper sediments for Branchiostoma belcheni are FMS, MS and CMS with MDΦ0. 547 to 2. 745Φ, QDΦ0. 536 to 0. 980, SKΦ - 0. 147 to 0. 101, MoΦ0. 731 to 3.152qo, respectively. The density of Branchiostoma beleheni was relatively higher when the proportion of particles in range from 0.2 to 0.85mm was large than 58%. A significant correlation was found existing between the distribution of Branchiostoma belcheni and the total proportion of particles from 0.2 to 0.85mm by hierarchical clustering and regression analysis. It was found that sandy sediments were important for the habitats of Branehiostoma belcheni in different areas, thought the size composition could be different.