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，科研团队在伊丽莎白与米德尔顿礁国家自然保护区内的伊丽莎白礁开展了鱼类、底栖生物及海参（bêche-de-mer）调查。本次共布设10个调查站位，覆盖三类受大洋环境影响程度各异的典型生境：隐蔽型泻湖（站位1）、礁渠或近礁渠区域（站位2与8）以及开阔型礁坡（其余7个站位）。礁坡站位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分异特征。
所有站位均开展了海参与蛤类的丰度评估。受潜水作业安全限制，调查水深限定在约9米范围内。
科研团队采用快速视觉评估方案（RAP，Rapid Visual Assessment Protocol）获取底栖群落的物种级数据及粗略丰度估算结果；同时利用视频样带调查，以更高的分类学分辨率获取更严谨的生物类群丰度估算数据。
鱼类群落的物种组成数据及粗略丰度估算，通过计时游泳快速视觉普查法获取；视觉普查样带可针对特定类群提供更精准的密度估算结果，同时为后续监测调查搭建可靠基线。
本次调查还在6-12米水深的泻湖及礁周区域，针对13种海参属（Holothuria，bêche-de-mer）生物、长棘海星（COTS，Crown of Thorns Starfish）及巨蛤（Tridacna gigas、Tridacna derasa）开展了专项调查。其中泻湖区域采用水肺潜水（SCUBA）搜索与浮潜巡游相结合的采样方式，礁周区域则仅采用水肺潜水（SCUBA）搜索采样。沿预设样带开展的水肺潜水搜索，用于统计不同体长等级的长棘海星数量、长棘海星侵害痕迹、食珊瑚螺（Drupella）及其他珊瑚死亡成因（包括珊瑚白化与珊瑚病害）。
科研团队再次采用快速视觉评估方案（RAP）获取底栖群落的物种级数据及粗略丰度估算，并通过视频样带调查以更高分类学分辨率获取更严谨的生物类群丰度估算结果。
本研究作为长期监测计划的一部分，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国家级保护地之一。该保护区距澳大利亚科夫斯港以东约600公里，距豪勋爵岛以北约200公里，总面积达18.8万公顷，包含全球最南端的开阔大洋平台礁群：伊丽莎白礁（约5100公顷）与米德尔顿礁（约3700公顷）。
这两处孤立礁体形成于塔斯曼海北部的火山海山之上，紧邻珊瑚海与塔斯曼海的交界区域，同时受热带与温带洋流的双重影响。该保护区于1987年12月23日正式宣告成立。保护区管理规划明确要求，将该礁群按世界自然保护联盟（IUCN）Ia类严格自然保护区的标准进行管理。此类保护区的核心定位为科学研究场地，以尽可能维持栖息地、生态系统与本土物种的未受干扰状态。此外，该保护区亦是国家海洋保护地代表性体系（NRSMPA，National Representative System of Marine Protected Areas）的重要组成部分。