涠洲岛珊瑚礁特点、演变及保护与修复对策的思考

涠洲岛珊瑚礁最早形成于约7 000年前的末次海侵,是中国大陆沿海成礁珊瑚分布最北缘的典型边缘珊瑚礁(Marginal Coral Reefs),与区域内其他珊瑚礁缺少生态关联,其特征不同于热带珊瑚礁,即块状珊瑚占优势。20多年来,涠洲岛珊瑚礁持续退化,枝状珊瑚大量死亡,石珊瑚盖度急剧降低,反映珊瑚礁良好状况的指标生物如鹦嘴鱼、蝴蝶鱼等的数量大幅减少。近10年来,珊瑚虽未出现异常死亡现象,但珊瑚自然修复不明显,表明珊瑚补充不足。功能性植食性鱼类的缺乏,显示珊瑚礁恢复力不足。涠洲岛珊瑚礁国家级海洋公园的建立,体现了保护涠洲岛珊瑚礁的政治意愿。只有恢复鹦嘴鱼等功能性植食性鱼类的数量,才能恢复和增强珊瑚礁固有恢复力,进而促进涠洲岛珊瑚礁的自然恢复。人为修复可采取移植珊瑚断枝的方式,并以实现生态、经济和社会增益为目标,构建能应对人为干预且能持续演化的珊瑚礁。

Reflections on the Characteristics,Evolution and Protection and Rehabilitation Strategies of the Coral Reefs at Weizhou Island

The coral reefs at Weizhou Island were first formed in the last marine transgression about 7 000 years ago.It is a typical marginal coral reefs that occurred at the most northern edge of coral reef distribution area along the coast of Mainland China.It lacks coral ecological connectivity with other coral reefs in the region,and its characteristics are different from tropical coral reefs.That is,mass corals dominate.For more than 20 years,coral reefs at Weizhou Island have continued to degenerate with mass mortality of branching corals,and the coverage of stony corals has dropped sharply.The number of indicator organisms that reflects the good condition of the coral reefs,such as parrotfish and butterfly fish,has remarkably reduced.Although there was no abnormal mortality of corals at Weizhou Island in the last ten years,the natural rehabilitation of coral reefs were not obvious,indicating insufficient coral replenishment.The lack of functional herbivorous fishes indicated that the resilience of coral reefs was weak.The establishment of Weizhou Island Coral Reefs National Maine Park reflected the political will of conserving the coral reefs at Weizhou Island.Only by restoring the number of functional herbivorous fish such as parrotfish,can the inherent resilience of coral reefs be restored and enhanced,thereby promoting the natural recovery of coral reefs at Weizhou Island.Artificial rehabilitation can take the method of coral fragment transplantation,and build a coral reef that can respond to human interference and continuous evolution of corals with the goal of achieving ecological,economic and social benefits.