Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, Japan.
Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, Japan.
Ecology. 2017 Jun;98(6):1524-1534. doi: 10.1002/ecy.1800. Epub 2017 Apr 26.
Larval dispersal significantly contributes to the geographic distribution, population dynamics, and evolutionary processes of animals endemic to deep-sea hydrothermal vents. Little is known as to the extent that their larvae migrate vertically to shallower waters and experience stronger currents and richer food supplies. Here, we first provide evidence from early life-history traits and population genetics for the surface dispersal of a vent species. Planktotrophic larvae of a red blood limpet, Shinkailepas myojinensis (Gastropoda: Neritimorpha: Phenacolepadidae), were cultured to observe their swimming behavior and to evaluate the effects of temperature on survival and growth. In addition, the population structure was analyzed based on 1.2-kbp mitochondrial DNA sequences from 77 specimens that cover the geographic and bathymetric distributions of the species (northwest Pacific, 442-1,227 m in depth). Hatched larvae constantly swam upward at 16.6-44.2 mm/min depending on temperature. Vertical migration from hydrothermal vents to the surface, calculated to take ~4-43 d, is attainable given their lengthy survival time without feeding. Fed larvae best survived and grew at 25°C (followed by 20°C), which approximates the sea surface temperature in the geographic range of the species. Little or no growth was observed at the temperature of the vent habitat where adult limpets occur (≤15°C). Population genetic analyses showed no differentiation among localities that are <1,350 km apart. The larvae of S. myojinensis most likely migrate to the surface water, where high phytoplankton biomass and strong currents enable their growth and long distance dispersal over many months. Sea surface temperature may represent a critical factor in determining the geographic distribution of many vent endemic species with a planktotrophic early development, and in turn the faunal composition of individual vent sites and regions.
幼虫扩散对深海热液喷口特有动物的地理分布、种群动态和进化过程有重要贡献。目前还不太清楚它们的幼虫是否会垂直迁移到较浅的水域，并经历更强的海流和更丰富的食物供应。在这里，我们首次从早期生活史特征和种群遗传学的角度为一种喷口物种的表面扩散提供了证据。一种红色血笠贝（Gastropoda: Neritimorpha: Phenacolepadidae）的浮游幼虫被培养以观察它们的游泳行为，并评估温度对生存和生长的影响。此外，基于覆盖物种地理和水深分布（西北太平洋，442-1227 米深处）的 77 个样本的 1.2-kbp 线粒体 DNA 序列，分析了种群结构。孵化后的幼虫根据温度以 16.6-44.2mm/min 的速度持续向上游动。从热液喷口到表面的垂直迁移，计算需要~4-43d，如果它们在没有食物的情况下有足够长的生存时间，是可行的。喂养的幼虫在 25°C（其次是 20°C）下最佳生存和生长，这与该物种地理分布范围内的海面温度相近。在成年笠贝栖息的喷口栖息地的温度下（≤15°C），几乎没有或没有观察到生长。种群遗传分析显示，相距<1350km 的地点之间没有分化。S. myojinensis 的幼虫很可能迁移到海面，那里高浮游植物生物量和强海流使它们能够生长并在数月内进行长距离扩散。海面温度可能是决定具有浮游幼虫早期发育的许多喷口特有物种地理分布的关键因素，进而决定单个喷口点和区域的动物组成。
