Fish and benthic community surveys of Elizabeth Reef in the Elizabeth and Middleton Reefs National Nature Reserve (Tasman Sea)

Fish, benthic and bêche-de-mer surveys were carried out on Elizabeth Reef in the Elizabeth and Middleton Reefs National Nature Reserve between the 2nd and 6th December 2003. 10 sites were surveyed, which encompassed three major habitat areas with different levels of exposure to oceanic conditions; sheltered lagoon (site 1), reef channel or near reef channel (sites 2 and 8) and exposed reef slopes (other seven sites). Reef slope sites were distributed evenly around the perimeter of Elizabeth Reef to encompass any local variation in reef communities due to reef orientation. The abundance of bêche-de-mer and clams were also assessed at all sites. Due to diving restrictions, surveys were limited to depths of around 9m.Species level data and crude abundance estimates of the benthic communities were obtained using a rapid visual assessment protocol (RAP). Video transect surveys were used to obtain more rigorous abundance estimates of biota at a finer taxonomic resolution.Species composition data and crude abundance estimates of the fish communities were obtained using a timed swim, rapid visual census method. Visual census transects provided more rigorous density estimates of a select group of species and a solid baseline for future monitoring surveys.Thirteen species of Holothuria (bêche-de-mer), crown of thorns starfish (COTS) and giant clams (Tridacna gigas and Tridacna derasa) were surveyed in the lagoon and on the reef perimeter at depths of 6-12m. The lagoon was sampled using SCUBA searches and snorkel swims and the reef perimeter was sampled using SCUBA searches. SCUBA searches, along transects, were used to provide information on numbers of COTS in defined size classes, COT scars, Drupella (a coral eating snail) and other sources of coral mortality including coral bleaching and coral disease. Species level data and crude abundance estimates of the benthic communities were obtained using a rapid visual assessment protocol (RAP). Video transect surveys were used to obtain more rigorous abundance estimates of biota at a finer taxonomic resolution.
This research was undertaken as part of a monitoring program, which will be used to determine the effectiveness of management practices within the National Nature Reserve.
The Elizabeth and Middleton Reefs Marine National Nature Reserve is one of two protected areas in the Tasman Sea region. The Reserve is located approximately 600 km east of Coffs Harbour and 200 km north of Lord Howe Island. The Reserve covers an area of 188,000 hectares, and includes the southern-most open-ocean platform reefs in the world: Elizabeth Reef (~5,100 ha) and Middleton Reef (~3,700 ha). Formed on volcanic seamounts in the northern Tasman Sea, these isolated reef systems lie close to the boundary between the Coral Sea and the Tasman Sea and are exposed to both tropical and temperate ocean currents. The Reserve was proclaimed on 23 December 1987. The Reserve management plan states that the reefs are to be managed as strict nature reserves - World Conservation Union (IUCN) category Ia. Such reserves are primarily for scientific research to ensure habitats, ecosystems, and native species are preserved in as undisturbed state as possible. The Reserve also forms part of the National Representative System of Marine Protected Areas (NRSMPA).

2003年12月2日至6日，研究团队在伊丽莎白与米德尔顿礁国家自然保护区的伊丽莎白礁开展了鱼类、底栖生物及海参（bêche-de-mer）调查。本次调查共布设10个站点，涵盖3类受大洋环境影响程度各异的主要生境：受庇护泻湖（1号站点）、礁通道或近礁通道（2号、8号站点）以及暴露型礁坡（其余7个站点）。礁坡站点沿伊丽莎白礁周边均匀分布，以覆盖因礁体朝向差异导致的珊瑚礁群落局部变异。所有站点均开展了海参与蛤类的丰度评估。受潜水作业限制，调查水深限定在约9米范围内。
底栖生物群落的物种级数据及粗略丰度估算采用快速视觉评估方案（rapid visual assessment protocol，缩写RAP）完成；采用视频样带调查以获取更高分类分辨率的生物群落实测丰度数据。鱼类群落的物种组成数据及粗略丰度估算采用计时游泳快速视觉普查法获取；视觉普查样带可为特定类群物种提供更精准的密度估算结果，同时为后续监测工作提供可靠基线。
在泻湖及礁周水深6-12米区域，调查了13种海参属（Holothuria）生物、棘冠海星（crown of thorns starfish，缩写COTS）以及巨砗磲（Tridacna gigas）和无鳞砗磲（Tridacna derasa）。泻湖区域采用水肺潜水搜索与浮潜巡游采样，礁周区域采用水肺潜水搜索采样。沿样带开展的水肺搜索用于获取特定体长分级的棘冠海星数量、棘冠海星侵袭疤痕、玫瑰螺属（Drupella，一种珊瑚食性螺类）以及包括珊瑚白化、珊瑚病害在内的其他珊瑚死亡成因数据。
底栖生物群落的物种级数据及粗略丰度估算采用快速视觉评估方案（RAP）完成；采用视频样带调查以获取更高分类分辨率的生物群落实测丰度数据。
本研究作为长期监测计划的一部分开展，旨在评估该国家自然保护区内各项管理措施的实施成效。
伊丽莎白与米德尔顿礁海洋国家自然保护区是塔斯曼海区域的两处保护区之一。该保护区位于科夫斯港以东约600公里、豪勋爵岛以北200公里处，总面积达18.8万公顷，包含全球最南端的开阔大洋台地礁：伊丽莎白礁（约5100公顷）与米德尔顿礁（约3700公顷）。这些孤立的礁体形成于塔斯曼海北部的火山海山之上，毗邻珊瑚海与塔斯曼海的交界地带，同时受热带与温带洋流双重影响。该保护区于1987年12月23日正式设立。
保护区管理规划明确，该礁群将按照世界自然保护联盟（World Conservation Union，IUCN）Ia类严格自然保护区标准进行管理。此类保护区的核心目标为开展科学研究，以尽可能维持栖息地、生态系统及本土物种的未受干扰状态。该保护区同时也是国家海洋保护区代表性系统（National Representative System of Marine Protected Areas，缩写NRSMPA）的组成部分。