永兴岛及七连屿造礁石珊瑚近10年变化分析

Analysis of the change of hermatypic corals in Yongxing Island and Qilianyu Island in nearly a decade

根据2007—2016年珊瑚礁监测数据,永兴岛及七连屿共调查到造礁石珊瑚11科113种,常见种有鹿角杯形珊瑚Pocillopora damicornis、疣状杯形珊瑚Pocillopora Verrucosa、粗野鹿角珊瑚Acropora humilis、澄黄滨珊瑚Porites lutea、丛生盔形珊瑚Galaxea fascicularis、梳状菊花珊瑚Goniastrea pectinata及锯齿刺星珊瑚Cyphastrea serailia等。研究区域内造礁石珊瑚种类近10年(2007—2016年)来下降明显,其中永兴岛从39种下降到18种,下降率为53.85%;北岛从23种下降到17种,下降率为26.09%;赵述岛从46种下降到12种,下降率为73.91%;西沙洲从51种下降到15种,下降率为70.59%。群体形态群落中皮壳状种类数最为稳定,分枝类下降了59.26%;叶片状下降了75.00%;圆盘状下降了87.50%;团块状下降了57.14%。通过对研究区域造礁石珊瑚种类组成及群落形态等方面的变化分析可见,人为活动、长棘海星、珊瑚病害、台风及全球升温等因素逐渐影响到西沙海域的珊瑚礁生态系统。

According to monitoring data of coral reefs from 2007 to 2016,there are 11 families and 113 species of hermatypic corals in Yongxing Islands and Qilianyu Islands,in which Pocillopora damicornis,P.verrucosa,Acropora humilis,Porites lutea,Galaxea fascicularis,Goniastrea pectinata and Cyphastrea serailia were common species.In nearly a decade（2007-2016）,species number of hermatypic corals significantly declined in survey area,and 53.85%reduction in species number from 39 to 19 was recorded in Yongxing Island,26.09%reduction from 23 to 17 in Bei Island,73.91%reduction from 46 to 12 in Zhaoshu Island,and 70.59%reduction from 51 to19 in Xishazhou Island.Analysis showed that the crusting hermatypic corals were stable in species number in nearly a decade,but other type of hermatypic corals showed a sharp decrease,59.26%for branching corals,75.0%for those with thin plate,87.50%for free-living Fungiidae corals and 57.14%for massive corals.The coral ecosystem in the Xisha Sea was gradually affected by anthropogenic activities,outbreak of crown-of-thorns starfish,coral disease,typhoons and global warming,based on the analysis of the changes of coral species composition and community forms in the study area.