Data from: Population genetic structure of eelgrass (Zostera marina) on the Korean coast: current status and conservation implications for future management

Seagrasses provide numerous ecosystem services for coastal and estuarine environments, such as nursery functions, erosion protection, pollution filtration, and carbon sequestration. Zostera marina (common name "eelgrass") is one of the seagrass bed-forming species distributed widely in the northern hemisphere, including the Korean Peninsula. Recently, however, there has been a drastic decline in the population size of Z. marina worldwide, including Korea. We examined the current population genetic status of this species on the southern coast of Korea by estimating the levels of genetic diversity and genetic structure of 10 geographic populations using eight nuclear microsatellite markers. The level of genetic diversity was found to be significantly lower for populations on Jeju Island [mean allelic richness (AR) = 1.92, clonal diversity (R) = 0.51], which is located approximately 155 km off the southernmost region of the Korean Peninsula, than for those in the South Sea (mean AR = 2.69, R = 0.82), which is on the southern coast of the mainland. South Korean eelgrass populations were substantially genetically divergent from one another (FST = 0.061-0.573), suggesting that limited contemporary gene flow has been taking place among populations. We also found weak but detectable temporal variation in genetic structure within a site over 10 years. In additional depth comparisons, statistically significant genetic differentiation was observed between shallow (or middle) and deep zones in two of three sites tested. Depleted genetic diversity, small effective population sizes (Ne) and limited connectivity for populations on Jeju Island indicate that these populations may be vulnerable to local extinction under changing environmental conditions, especially given that Jeju Island is one of the fastest warming regions around the world. Overall, our work will inform conservation and restoration efforts, including transplantation for eelgrass populations at the southern tip of the Korean Peninsula, for this ecologically important species.海草为沿海及河口湾生境提供诸多生态系统服务，诸如育苗功能、侵蚀防护、污染净化与碳封存。鳗草（Zostera marina，俗称"eelgrass"）是广泛分布于北半球（包括朝鲜半岛）的海草床建群物种之一。然而近年来，全球范围内包括韩国在内的鳗草种群数量均出现急剧下降。本研究通过8个核微卫星标记（nuclear microsatellite markers）对韩国南部海岸的10个地理种群的遗传多样性水平与遗传结构进行评估，以探究该物种的当前种群遗传现状。研究发现，位于朝鲜半岛最南端外海约155公里处的济州岛种群，其遗传多样性水平显著低于大陆南岸的南海海域种群：济州岛种群的平均等位基因丰富度（allelic richness, AR）为1.92，克隆多样性（clonal diversity, R）为0.51；南海种群的平均等位基因丰富度为2.69，克隆多样性为0.82。韩国境内的鳗草种群间存在显著遗传分化（FST=0.061~0.573），表明种群间当代基因流受限。此外，我们还检测到某一样地的遗传结构在10年时间尺度上存在微弱但可被识别的时间变异。在额外的深度梯度比较实验中，3个受试样地中的2个样地内，浅水区（或中水区）与深水区种群间存在统计学意义上的显著遗传分化。济州岛种群存在遗传多样性匮乏、有效种群大小（effective population size, Ne）偏小以及连通性受限的问题，这表明这些种群在环境变化的背景下易发生局部灭绝；加之济州岛是全球变暖速度最快的区域之一，该风险尤为突出。总体而言，本研究可为这一具有重要生态价值的物种的保护与修复工作提供科学依据，包括针对朝鲜半岛南端鳗草种群的移植修复工作。