Data from: Patterns and persistence of larval retention and connectivity in a marine fish metapopulation

Connectivity, the demographic linking of local populations through the dispersal of individuals, is one of the most poorly understood processes in population dynamics, yet has profound implications for conservation and harvest strategies. For marine species with pelagic larvae, direct estimation of connectivity remains logistically challenging and has mostly been limited to single snapshots in time. Here, we document seasonal and interannual patterns of larval dispersal in a metapopulation of the coral reef fish Amphiprion polymnus. A 3-year record of larval trajectories within and among nine discrete local populations from an area of approximately 35 km was established by determining the natal origin of settled juveniles through DNA parentage analysis. We found that spatial patterns of both self-recruitment and connectivity were remarkably consistent over time, with a low level of self-recruitment at the scale of individual sites. Connectivity among sites was common and multidirectional in all years and was not significantly influenced by seasonal variability of predominant surface current directions. However, approximately 75% of the sampled juveniles could not be assigned to parents within the study area, indicating high levels of immigrations from sources outside the study area. The data support predictions that the magnitude and temporal stability of larval connectivity decreases significantly with increasing distance between subpopulations, but increases with the size of subpopulations. Given the considerable effort needed to directly measure larval exchange, the consistent patterns suggest snapshot parentage analyses can provide useful dispersal estimates to inform spatial management decisions.

种群连通性（Connectivity）指通过个体扩散实现的局域种群间的人口统计学联系，是种群动态学中认知程度最低的过程之一，却对物种保护与捕捞策略有着深远影响。对于具有浮游幼体的海洋物种而言，直接估算种群连通性仍面临诸多后勤难题，且大多仅能获取单一时间点的快照式数据。本研究针对珊瑚礁鱼类三带双锯鱼（Amphiprion polymnus）的集合种群（metapopulation），记录了其幼体扩散的季节与年际变化模式。本研究通过DNA亲权分析（DNA parentage analysis）确定定居幼体的出生地来源，构建了覆盖约35平方公里区域内9个独立局域种群内部及相互间的幼体扩散轨迹的3年观测记录。研究发现，自我补充与种群连通性的空间格局在时间尺度上表现出显著一致性，单个样地尺度下的自我补充水平较低。各站点间的种群连通性在所有年份中普遍存在且呈多向性，且未受表层海流主导方向季节波动的显著影响。但约75%的采样幼体无法匹配到研究区域内的亲本，表明有大量幼体从研究区域外的种群迁入。本研究数据验证了相关预测：幼体连通性的强度与时间稳定性会随亚种群间距离的增加而显著降低，但会随亚种群规模的扩大而提升。考虑到直接测量幼体交换需要投入大量工作量，这些一致的格局表明，快照式亲权分析可提供有效的扩散估算数据，为空间管理决策提供依据。