中文摘要：

对三亚鹿回头珊瑚岸礁5条断面进行实地潜水调查并室内判读海底录像,得到该岸段2005年和2006年的礁坡活珊瑚覆盖率分别为14.79%和12.16%。与历史资料（1960年、1978年、1983年和1990年测值分别为80%—90%、60%、60%和35%,1998年约为41.5%,2002年为23.4%,2004年为20%）对比分析显示,近50年来该岸段活珊瑚覆盖率显著下降,珊瑚礁总体呈衰退趋势。研究表明,人类活动是造成三亚鹿回头珊瑚礁衰退并影响将来发展的重要因素：过度和破坏性捕捞以及大规模采挖礁块等活动直接导致了该岸段珊瑚礁在七八十年代出现的巨大衰退;海上珍珠贝、麒麟菜等养殖活动是造成近期破坏的主要原因;正在影响该岸段珊瑚礁覆盖率仍持续下降的主要原因是沿岸对虾或鲍育苗养殖;三亚河和近海工程建设、航运活动带来的泥沙和污染物以及正向鹿回头扩展的潜水旅游活动已成为不可忽视的威胁。所以,保护该岸段珊瑚礁,需要在了解该岸礁活珊瑚覆盖率动态变化的基础上认清保护管理的紧迫性,并针对不同区域珊瑚群落的具体特征和影响因素制定合理、有效的管理措施。

英文摘要：

Five transects in Luhuitou Fringing Reef,Sanya,Hainan,China,were studied by scuba observation and laboratory interpretation from video transects and photo quadrats in 2005 and 2006;the mean live coral cover was 15% and 12% respectively.The live coral cover has been remarkably decreased.Prosperous coral communities were flourish in the past,in coverage of as high as 80%—90% in 1960s.Live coral cover was 60% in 1978 and 1983,and 35% in 1990,indicating a considerable degradation.It increased to 42% in 1998,but reduced again to 23% in 2002 and 20% in 2004,in downtrend at the investigation period.The human activities were the main factors on the reduction of live coral cover.Overfishing,destructive fishing activities,and large-scale reef rock quarrying in 1970s to 1980s directly resulted in the huge decline,maricultures of pearl oyster and Eucheuma led to recent reef destruction,and a dozen of breeding farms for prawn or abalone in Luhuitou coastal region may also be responsible for the degradation at present.Besides,sediment and pollutant from land,coastal engineering,and diving-oriented tourism has become another potential threat.Therefore,in order to protect the coral reef ecology,dynamic real-time long-term monitoring on live coral cover shall be implemented with reasonable and effective management measures.