Tiny Is Mighty: Seagrass Beds Have a Large Role in the Export of Organic Material in the Tropical Coastal Zone
Tiny Is Mighty: Seagrass Beds Have a Large Role in the Export of Organic Material in the Tropical Coastal Zone
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微小即强大：海草床在热带沿海地区有机材料的出口中发挥着重要作用
作者：
L. Gillis;A. Ziegler;D. van Oevelen;C. Cathalot;P. Herman;Jan‐Willem Wolters;T. Bouma
热带沿海地区的生态系统与相邻系统交换颗粒有机质(POM)，但不同生态系统之间这一功能的差异仍然很难量化。海草床通常是这一海岸带相对较小的一部分，但其潜在的生态影响比它们的表面积所暗示的要大得多。利用稳定同位素作为海洋、陆地、红树林和海草来源的示踪剂，研究了泰国普吉岛周围9个红树林海湾颗粒态有机质的来源。我们使用基于总体有机碳、总氮和δ13C和δ15N的线性混合模型，发现沿红树林-海草-海洋梯度的悬浮颗粒有机质样品以海洋来源为主。沉积物捕捉器样品的贡献来自海洋、红树林/陆地和海草床四个来源，其中海洋的贡献最大，海草的贡献最小。然而，从生态系统面积来看，相对于红树林、集水区(陆地)和海草床占据的整个面积，来自海草床的悬浮颗粒有机质的贡献高得不成比例。红树林的贡献大致等于它们的表面积，而相对于它们的相对集水区面积，红树林对悬浮有机质的贡献是陆源的。值得注意的是，样带0m处红树林的贡献与红树林暴露的额面宽度呈正相关，表明红树林暴露于水动力能中可能是红树林向外迁移的控制因素。然而，我们没有发现海草床贡献与我们测量的任何物理因素之间的关系。我们的结果表明，尽管海草床在海岸带的面积相对较小，但它们在输出有机质方面的作用是不成比例的，在海岸管理中应该考虑到它们作为其他生态系统和生物的营养源的重要性。
Ecosystems in the tropical coastal zone exchange particulate organic matter (POM) with adjacent systems, but differences in this function among ecosystems remain poorly quantified. Seagrass beds are often a relatively small section of this coastal zone, but have a potentially much larger ecological influence than suggested by their surface area. Using stable isotopes as tracers of oceanic, terrestrial, mangrove and seagrass sources, we investigated the origin of particulate organic matter in nine mangrove bays around the island of Phuket (Thailand). We used a linear mixing model based on bulk organic carbon, total nitrogen and δ13C and δ15N and found that oceanic sources dominated suspended particulate organic matter samples along the mangrove-seagrass-ocean gradient. Sediment trap samples showed contributions from four sources oceanic, mangrove forest/terrestrial and seagrass beds where oceanic had the strongest contribution and seagrass beds the smallest. Based on ecosystem area, however, the contribution of suspended particulate organic matter derived from seagrass beds was disproportionally high, relative to the entire area occupied by mangrove forests, the catchment area (terrestrial) and seagrass beds. The contribution from mangrove forests was approximately equal to their surface area, whereas terrestrial contributions to suspended organic matter under contributed compared to their relative catchment area. Interestingly, mangrove forest contribution at 0 m on the transects showed a positive relationship with the exposed frontal width of the mangrove, indicating that mangrove forest exposure to hydrodynamic energy may be a controlling factor in mangrove outwelling. However we found no relationship between seagrass bed contribution and any physical factors, which we measured. Our results indicate that although seagrass beds occupy a relatively small area of the coastal zone, their role in the export of organic matter is disproportional and should be considered in coastal management especially with respect to their importance as a nutrient source for other ecosystems and organisms.