西沙群岛永兴岛礁坡石珊瑚覆盖率的空间变化  

Spatial variations of stony coral cover on the reef slope of Yongxing Island,Xisha Islands

作　　者：施祺[1] 严宏强[1] 张会领[1] 赵美霞[1] 

机构地区：[1]中国科学院边缘海地质重点实验室,中国科学院南海海洋研究所,广东广州510301

出　　处：《热带海洋学报》2011年第2期10-17,共8页Journal of Tropical Oceanography

基　　金：海洋公益性行业科研专项(200705026);国家自然科学基金项目(40830852、41025007、40906043);国家重点基础研究发展计划项目(2007CB815905);中国科学院知识创新工程重要方向项目(KZCX2-YW-318)

摘　　要：连续影像样方调查方法较常用的截线样条法具有空间分辨率高的特点。采用该方法于2008年7月在西沙群岛永兴岛礁坡开展了5条垂直岸线断面和2条平行岸线断面的石珊瑚覆盖率调查。调查发现,永兴岛珊瑚覆盖率存在显著的空间差异,北、西北和东部断面珊瑚分布相对较多,覆盖率较高;西和西南部断面珊瑚分布稀少,覆盖率低。其中北、西北和东部断面沿礁坡方向珊瑚分布明显减少,礁坡中上部30—50m以上、水深5—6m以浅的区域,珊瑚覆盖率高;而礁坡中下部50m以下、水深约6m以深区域,珊瑚分布少,覆盖率低。此外,北和西北部断面还发现由棘冠海星Acanthaster planci和黑皮海绵Terpios hoshinota分别造成的珊瑚白化和珊瑚黑死现象,一定程度上降低了珊瑚覆盖率。永兴岛珊瑚覆盖率的下降以及空间变化格局的形成主要与30年以来日益增加的人类活动和珊瑚礁区过度开发有关。A method of successive image quadrat has characteristics of high spatial resolution,comparing with a conventional method of line intercept transect.This study investigated stony coral covers of five transects perpendicular to the coastline and two transects parallel to the coastline over the reef slope of Yongxing Island,one of the Xisha Islands,in July 2008 using the successive image quadrat method.The results reveal an evident spatial difference of cover rate of the reef slope,which was distributed widely with high cover rates along the transects over the northern,northwestern,and eastern slopes and scattered rarely with low cover rates along the transects over the western and southwestern slopes.Along the transects over the northern,northwestern,and eastern slopes corals reduced obviously along the slopes,showing relatively high abundance with high cover rate in the areas of upper slopes over 30？50 m and shallower than 5？6 m and less abundance with low cover rate in the areas of lower slope below 50 m and deeper than 6 m.Moreover,coral bleaching caused by Acanthaster planci and coral black disease caused by Terpios hoshinota were found along the transects of the northern and northwestern slopes,which reduced the coral cover rates by a certain amount.The decline of coral cover and formation of spatial variation pattern on Yongxing Island are related primarily to the increasing human impact and the excessive exploitation of the reef.

关 键 词：覆盖率 石珊瑚 白化 黑死 永兴岛 

分 类 号：P735[天文地球—海洋生物学]