Elkhorn Slough eelgrass restoration

The global decline of marine foundation species (kelp forests, mangroves, salt marshes, and seagrasses) has contributed to the degradation of the coastal zone and threatens the loss of critical ecosystem services and functions. Restoration of marine foundation species has had variable success, especially for seagrasses, where a majority of restoration efforts have failed. While most seagrass restorations track structural attributes over time, rarely do restorations assess the suite of ecological functions that may be affected by restoration. Here we report on the results of two small-scale experimental seagrass restoration efforts in a central California estuary where we transplanted 117 0.25 m2 plots (2,340 shoots) of the seagrass species Zostera marina. We quantified restoration success relative to persistent reference beds, and in comparison to unrestored, unvegetated areas. Within three years, our restored plots expanded ~8500%, from a total initial area of 29 m2 to 2513 m2. The restored beds rapidly began to resemble the reference beds in 1) seagrass structural attributes (canopy height, shoot density, biomass), 2) ecological functions (macrofaunal species richness and abundance, epifaunal species richness, nursery function), and 3) biogeochemical functions (modulation of water quality). We also developed a multifunctionality index to assess cumulative functional performance, which revealed restored plots are intermediate between reference and unvegetated habitats, illustrating how rapidly multiple functions recovered over a short time period. Our comprehensive study is one of few published studies to quantify how seagrass restoration can enhance both biological and biogeochemical functions. Our study serves as a model for quantifying ecosystem services associated with the restoration of a foundation species and demonstrates the potential for rapid functional recovery that can be achieved through targeted restoration of fast-growing foundation species under suitable conditions.

全球海洋建群种（marine foundation species，包括海带林、红树林、盐沼与海草）的衰退加剧了海岸带退化，并威胁到关键生态系统服务与功能的丧失。海洋建群种的修复成效差异显著，尤以海草修复为甚——绝大多数海草修复项目均以失败告终。尽管多数海草修复研究会随时间追踪其结构特征，但极少有研究评估修复可能影响的全套生态功能。

本研究针对加州中部河口开展的两处小型海草修复实验进行结果汇报，我们共移栽了117块0.25平方米的样地（总计2340株），供试海草物种为大叶藻（Zostera marina）。我们以长期存在的自然参考海草床为参照，并与未修复的无植被区域对比，量化了修复成效。短短三年内，修复样地的总面积从初始的29平方米扩张至2513平方米，扩张幅度约达8500%。

修复海草床在三个维度快速趋近参考海草床：1）海草结构特征（冠层高度、株丛密度、生物量）；2）生态功能（大型底栖动物物种丰富度与多度、表栖动物物种丰富度、育苗功能）；3）生物地球化学功能（水质调控功能）。我们还构建了多功能性指数（multifunctionality index）以评估累积功能表现，结果显示修复样地的功能表现介于参考海草床与无植被生境之间，表明短时间内多项生态功能即可实现快速恢复。

本综合研究是目前为数不多公开报道的、可量化海草修复如何同时提升生物与生物地球化学功能的研究之一。本研究为量化建群种修复所关联的生态系统服务提供了示范模型，并证实：在适宜环境条件下，通过针对性修复快速生长的建群种，即可实现生态功能的快速恢复。