当代的连通性是由海风和海流驱动的海草床种子扩散维持的。
Contemporary connectivity is sustained by wind- and current-driven seed dispersal among seagrass meadows.
机构信息
The School of Earth and Environment, The University of Western Australia, Crawley, Western Australia Australia ; The School of Plant Biology, The University of Western Australia, Crawley, Western Australia Australia ; The University of Western Australia Oceans Institute, Crawley, Western Australia Australia.
The School of Earth and Environment, The University of Western Australia, Crawley, Western Australia Australia ; The University of Western Australia Oceans Institute, Crawley, Western Australia Australia ; ARC Centre of Excellence for Coral Reef Studies, Crawley, Western Australia Australia.
出版信息
Mov Ecol. 2015 Apr 2;3(1):9. doi: 10.1186/s40462-015-0034-9. eCollection 2015.
BACKGROUND
Seagrasses are clonal marine plants that form important biotic habitats in many tropical and temperate coastal ecosystems. While there is a reasonable understanding of the dynamics of asexual (vegetative) growth in seagrasses, sexual reproduction and the dispersal pathways of the seeds remain poorly studied. Here we address the potential for a predominantly clonal seagrass, P. australis, to disperse over long distances by movement of floating fruit via wind and surface currents within the coastal waters of Perth, Western Australia. We first simulated the dominant atmospheric and ocean forcing conditions that are known to disperse these seagrass seeds using a three-dimensional numerical ocean circulation model. Field observations obtained at 8 sites across the study area were used to validate the model performance over ~2 months in summer when buoyant P. australis fruit are released into the water column. P. australis fruit dispersal trajectories were then quantified throughout the region by incorporating key physical properties of the fruit within the transport model. The time taken for the floating fruit to release their seed (dehiscence) was incorporated into the model based on laboratory measurements, and was used to predict the settlement probability distributions across the model domain.
RESULTS
The results revealed that high rates of local and regional demographic connectivity among P. australis meadows are achieved via contemporary seed dispersal. Dispersal of seeds via floating fruit has the potential to regularly connect meadows at distances of 10s of kilometres (50% of seeds produced) and infrequently for meadows at distances 100 s km (3% of seeds produced).
CONCLUSIONS
The spatial patterns of seed dispersal were heavily influenced by atmospheric and oceanographic conditions, which generally drove a northward pattern of connectivity on a regional scale, but with geographical barriers influencing finer-scale connectivity pathways at some locations. Such levels of seed dispersal infer greater levels of ecological and genetic connectivity and suggest that seagrasses are not just strongly clonal.
背景
海草是克隆海洋植物，在许多热带和温带沿海生态系统中形成重要的生物栖息地。虽然人们对海草无性（营养）生长的动态有合理的了解，但有性繁殖和种子的扩散途径仍研究甚少。在这里，我们研究了主要克隆海草 P. australis 是否有可能通过风和沿海水域表面流在西澳大利亚珀斯的沿海地区远距离传播漂浮的果实。我们首先使用三维数值海洋环流模型模拟了已知会分散这些海草种子的主要大气和海洋强迫条件。在夏季，当有浮力的 P. australis 果实释放到水柱中时，我们在研究区域的 8 个地点进行了实地观测，使用这些观测来验证模型在大约 2 个月内的性能。然后，通过在运输模型中纳入果实的关键物理特性，在整个区域量化 P. australis 果实的扩散轨迹。根据实验室测量结果，将漂浮果实释放种子（开裂）所需的时间纳入模型中，并用于预测模型域内的定居概率分布。
结果
结果表明，通过当代种子扩散，P. australis 草地之间实现了高局部和区域人口连通率。漂浮果实的种子扩散有可能定期连接距离数十公里的草地（产生的种子的 50%），并且偶尔连接距离 100 公里的草地（产生的种子的 3%）。
结论
种子扩散的空间模式受大气和海洋条件的强烈影响，这些条件通常在区域尺度上驱动连通性的向北模式，但在某些位置的地理障碍影响更精细尺度的连通性途径。这种水平的种子扩散推断出更高水平的生态和遗传连通性，并表明海草不仅是强烈的克隆。
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