涠洲岛珊瑚健康及其影响因子分析

根据2007年秋至2008年春间,涠洲岛6条主剖面15条断面的珊瑚和底质覆盖率、珊瑚补充量、死亡指数的一次两阶段的调查数据和同期4个季度月的水环境调查数据,结合以往的研究成果,初步分析了涠洲岛珊瑚健康状况及其影响因子。结果表明,调查断面珊瑚死亡指数平均为40.90%,珊瑚死亡发生于本次调查的两年前;珊瑚有恢复的迹象,但珊瑚补充量小,珊瑚补充量与活珊瑚+死珊瑚覆盖率显著相关(r=0.520,P<0.05);除汞、铅、锌和油类外,涠洲岛珊瑚礁海区水体的理化、生物因子符合一类海水水质标准,大体上呈微营养水平,春季的水体营养指数明显高于其他季节。涠洲岛珊瑚死亡率高和恢复慢,表明珊瑚处于退化中的亚健康状态。

Preliminary Analysis on the Coral Health and Its Influential Factors in Weizhou Island

Preliminary analysis on the coral health and its influential factors in Weizhou Island was carried out with the data, which included the coverage of corals and substrate, coral recruitment, mortality index and seawater qualities, derived from a coral survey that conducted along fifteen transects of six profiles in Weizhou Island from the Autumn of 2007 to the Spring of 2008 and the results of previous study.The results showed that average mortality index (MI) of corals at the survey transects was 40.90%, and basically the dead corals died two years ago before the survey time.Coral recruitment was observed, but the recruitment rate was low and significantly correlated with the coral (live and dead) cover.All physical, chemical and biological factors in the seawater of Weizhou Island, except for Hg, Pb, Zn, and oil, fell within the seawater quality criteria of category 1.The seawater of Weizhou Island was slightly nutritious, judged upon the nutrition quality index, which was significantly higher in spring than in other seasons.Mass mortalities and slow recovery of corals at Weizhou Island indicated that the corals are sub-healthy and in the trend of degradation.