三亚鹿回头石珊瑚物种多样性的空间分布

Spatial pattern of coral diversity in Luhuitou fringing reef,Sanya

对三亚鹿回头珊瑚岸礁沿垂直岸线的5条断面上84个调查样方观测照相和室内判读分析,鹿回头岸段石珊瑚共有13科24属69种,珊瑚分布不均,少数种类优势明显。石珊瑚优势种为澄黄滨珊瑚,其重要值百分比为36.62%;优势属为滨珊瑚属(43.85%)和鹿角珊瑚属(22.88%)。各断面间多样性格局差异明显,并存在明显的垂直分带现象:东北部第1、2断面石珊瑚种类分布较为均匀,多样性指数值高于中南部第3、4、5断面;礁坪为珊瑚稀疏生长带,种类较少且滨珊瑚为绝对优势属(重要值百分比>50%);礁坡为珊瑚密集生长带,种类较多以鹿角珊瑚最占优势(28.33%),滨珊瑚仅次之(26.71%)。近年来该岸段珊瑚礁衰退趋势明显,不合理的破坏性人类活动是重要原因。石珊瑚多样性的空间差异除因礁坪礁坡不同的自然环境外,主要与受到不同类型和强度的人类活动有关。礁坪大潮低潮时暴露,环境恶劣,且受人类采挖、践踏活动影响较频繁和明显;礁坡环境适宜,人类活动影响也相对微弱。养殖、捕捞和近岸排污等人类活动在岸段中南部较为突出,对珊瑚多样性的影响比东北部明显。在尊重珊瑚礁发育的自然规律基础上不断加大力度制止养殖、不合理捕捞和近岸排污等破坏性人类活动,才能更好地科学保护和管理该岸段珊瑚礁。

84 quadrats from 5 vertical transects on Luhuitou fringing reef are investigated in detail using video-quadrat and indoor-interpretation methods. The results show that ： （ 1 ） The reef consists of 69 species of hermatypic corals belonging to 24 genera and 13 families which are unevenly distributed in abundance. （2） Among all the corals, Porites lutea is the most dominant species with importance value percentages up to 36. 62% ; Porites and Acropora are dominant genera, with importance value percentages as 43.85% and 22.88% , respectively. （3） There exist distinct spatial differences in coral communities： both the coral covers and coral diversity indexes in the northeastern transects are higher than those in the central and southern transects. （4） Coral communities also show remarkable zonal characteristics, with less coral species occurring in reef flat than in reef slope. The importance value percentage of the sole dominant coral genus, Porites, is over 50% , while in the reef slope, the importance value percentages are 28.33% for the first dominant genus Acropora and 26.71% for the second dominant genus Porites. Our further analysis suggests that the spatial and zonal differences of coral diversity pattern are correlated with both natural environmental changes and human activities. The shallow water reef flat frequently exposes at low tide and receives more anthropogenic influences （ including dredging and trampling） than the deep water reef slope. Thus, the coral community in the reef flat is not as well developed as that in reef slope. The relatively poor coral covers and coral diversity indexes in the central and southern transects are closely related to heavy human activities around these sites, such as aquaculture, fishing and coastal sewage. Therefore, the impact of human activities must be taken into account when developing strategies for the protection of this coral reef.