Community change in the algal endosymbionts of a scleractinian coral following a natural bleaching event on the Great Barrier Reef

The symbiont community of 460 randomly sampled colonies of Acropora millepora from a reef flat adjacent to Miall Island (Keppel Islands, Great Barrier Reef) were analysed after a natural bleaching event in early 2006. To determine the Symbiodinium community composition, 460 colonies were tagged on the reef flat at Miall Island between September 2004 and March 2005. A combination of single-stranded conformation polymorphism (SSCP) analysis, cloning and DNA sequencing was used for symbiont identification. Symbionts were: the thermally sensitive Symbiodinium type C2, a tolerant Symbiodinium type belonging to clade D, mixtures of C2 and D, and C1. Background types were also recorded.A subset of 79 colonies that survived the bleaching 3 and 6 months (May and August, respectively) after the bleaching event in January/February 2006 were examined for symbiont changes. These colonies were chosen haphazardly from surviving colonies and comprised 58 with predominantly C2-type, 15 with predominantly D-type and 6 with both C2 and D types present.Mortality in the Acropora millepora population was assessed 6 months after the bleaching event in August 2006 by visually estimating the percentage (

2006年初发生自然白化事件后，研究人员对取自大堡礁凯珀尔群岛（Keppel Islands）迈尔岛（Miall Island）附近礁坪的460株随机采样的千孔鹿角珊瑚（Acropora millepora）群体的共生菌群落进行了分析。为明确虫黄藻（Symbiodinium）群落组成，研究人员于2004年9月至2005年3月间，在迈尔岛礁坪对460株珊瑚群体进行了标记。本研究采用单链构象多态性分析（single-stranded conformation polymorphism, SSCP）、克隆技术与DNA测序相结合的方法开展共生菌鉴定工作。本次鉴定得到的虫黄藻类群包括：热敏感型C2类群、隶属于D进化枝的耐受型虫黄藻类群、C2与D的混合类群以及C1类群，同时研究人员还记录了背景类群。针对2006年1-2月白化事件后存活的79株珊瑚群体，研究人员分别在白化后3个月（2006年5月）与6个月（2006年8月）对其共生菌群落变化进行了检测。该79株珊瑚群体均从存活个体中随机选取，其中58株以C2类群为优势类群，15株以D类群为优势类群，剩余6株同时存在C2与D两类群。研究人员于2006年8月，即白化事件发生6个月后，通过目视估算百分比的方式对千孔鹿角珊瑚（Acropora millepora）种群的死亡率进行了评估（