The Real Bounty: Marine Biodiversity in the Pitcairn Islands

In 2012 we conducted an integrated ecological assessment of the marine environment of the Pitcairn Islands, which are four of the most remote islands in the world. The islands and atolls (Ducie, Henderson, Oeno, and Pitcairn) are situated in the central South Pacific, halfway between New Zealand and South America. We surveyed algae, corals, mobile invertebrates, and fishes at 97 sites between 5 and 30 m depth, and found 51 new records for algae, 23 for corals, and 15 for fishes. The structure of the ecological communities was correlated with age, isolation, and geomorphology of the four islands. Coral and algal assemblages were significantly different among islands with Ducie having the highest coral cover (56%) and Pitcairn dominated by erect macroalgae (42%). Fish biomass was dominated by top predators at Ducie (62% of total fish biomass) and at Henderson (35%). Herbivorous fishes dominated at Pitcairn, while Oeno showed a balanced fish trophic structure. We found high levels of regional endemism in the fish assemblages across the islands (45%), with the highest level observed at Ducie (56% by number). We conducted the first surveys of the deep habitats around the Pitcairn Islands using drop-cameras at 21 sites from depths of 78 to 1,585 m. We observed 57 fish species from the drop-cams, including rare species such as the false catshark (Pseudotriakis microdon) and several new undescribed species. In addition, we made observations of typically shallow reef sharks and other reef fishes at depths down to 300 m. Our findings highlight the uniqueness and high biodiversity value of the Pitcairn Islands as one of the least impacted in the Pacific, and suggest the need for immediate protection.

于2012年，我们对皮特凯恩群岛的海洋环境进行了全面的生态评估。皮特凯恩群岛是世界上海拔最高的四个偏远岛屿之一。这些岛屿和环礁（包括杜西、亨德森、奥诺和皮特凯恩）位于中南部太平洋，新西兰与南美洲之间的中点。我们在5至30米深度的97个位点对藻类、珊瑚、移动的无脊椎动物和鱼类进行了调查，发现了51种新的藻类记录、23种珊瑚记录和15种鱼类记录。生态群落的结构与其所在岛屿的年龄、隔离程度和地形密切相关。珊瑚和藻类群落在不同岛屿间存在显著差异，杜西岛珊瑚覆盖率最高（达56%），而皮特凯恩岛则以直立的大型藻类为主（占42%）。在杜西岛和亨德森岛，鱼类生物量主要由顶级捕食者构成，分别占总生物量的62%和35%。在皮特凯恩岛，食草鱼类占主导地位，而奥诺岛则显示出平衡的鱼类营养结构。我们在岛屿鱼类群落中发现了高水平的区域特有性（45%），其中杜西岛以数量计的特有性最高（达56%）。我们首次使用投掷式摄像机对皮特凯恩群岛周边的深海栖息地进行调查，共调查了21个位点，深度从78米至1,585米。投掷式摄像机观察到57种鱼类，包括如假猫鲨（Pseudotriakis microdon）等罕见物种以及数种未描述的新物种。此外，我们还观察到在300米深度的浅水礁鲨和其他礁鱼类。我们的研究突显了皮特凯恩群岛的独特性和高生物多样性价值，该群岛在太平洋中受影响最小，并表明了迫切需要对其进行保护。