茂名大放鸡海域文昌鱼、蛇尾分布及其与底质粒度特征的关系

Distribution of Branchiostoma belcheri and Amphiura vadicola in Relation to Bottom Grain Size in Dafangji Waters,Maoming

为给茂名市建设文昌鱼省级自然保护区提供基础资料，根据2003年8月～2004年5月间对茂名大放鸡海域的调查结果，对文昌鱼和蛇尾的分布特性进行了研究。结果表明：文昌鱼和蛇尾均呈集群分布，在空间分布上表现为正相关关系，不存在强烈的竞争关系。文昌鱼主要分布在中值粒径Mdφ为0．4～2．2之间砂质中。在0．5≤Mdφ〈1．5范围内，文昌鱼分布密度相对地高，而在Mdφ〈0．5或Mdφ≥1．5范围内，文昌鱼分布密度相对较低。粒径0．36～0．78mm组分〈50％时，文昌鱼分布密度≤50ind／m^2；粒径0．36～0．78mm组分≥50％时，文昌鱼分布密度〉100ind／m^2。蛇尾分布在中值粒径Mdφ为0．2～0．8之间砂质中。粒径0．36～0．78mm组分占10％～50％时，蛇尾分布密度较低，而粒径0．36～0．78mm组分占60％～80％时，蛇尾分布密度较高。

Distribution of Branchiostoma belcheri and Amphiura vadicola is analyzed based on marine biological surveys conducted in Dafangji waters, Maoming during August 2003 to May 2004. Both Branchiostoma belcheri and Amphiura vadicola distribute in clusters. Their inter-species relationship proves to be positive in spatial distribution, and they do not compete strongly. Branchiostoma belcheri is mainly distributed in sand with median diameter φ（Mdφ） from 0.4 to 2.2 and its density is large for Mdφ ranging from 0.5 to 1.5 and small in the remaining intervals of Mdφ. It is greater than 100 ind/m^2 where the granularity of 0.36-0.78 mm group is greater than 50 percent and less than 50 ind/m^2 otherwise. Amphiura vadicola is mainly distributed in sand with Mdφ ranging from 0.2 to 0.8. Its density is dramatically greater where the granularity in 0.36-0.78 mm group lies from 60 to 80 percent than where the granularity of the same group if from 10 to 50 percent.