Data from: Effects of small-scale, shading-induced seagrass loss on blue carbon storage: Implications for management of degraded seagrass ecosystems

1. Seagrass meadows are important global ‘blue carbon’ sinks. Despite a
30% loss of seagrasses globally during the last century, there is limited
empirical research investigating the effects of disturbance and loss of
seagrass on blue carbon stocks. 2. In this study, we hypothesised that
seagrass loss would reduce blue carbon stocks. Using shading cloth, we
simulated small-scale die-offs of two subtropical seagrass species,
Halodule wrightii and Thalassia testudinum, in a dynamic northern Gulf of
Mexico lagoon. The change in quantity and quality of sediment organic
matter and organic carbon were compared among kill, control and bare plots
before the kill treatment, shortly after the kill treatment and 11 months
after the kill treatment. 210 Pb age dating was performed on bare and
Thalassia plots at 11 months to evaluate the impact of sediment erosion in
the absence of vegetation. 3. The small-scale die-off led to a 50-65%
organic matter (OM) loss in the sediment in the top 8 cm of Halodule
plots. Thalassia plots lost significant portions OM (50%) and organic
carbon (C; 21-47%) in only the top 1 cm of sediment. The 210 Pb profiles
indicated Thalassia die-off reduced the C sequestration rate by 10%, in
addition to a loss of ~1 years’ worth of C stocks (~22 g m-2<).
Furthermore, analyses on O Morg quality indicated a loss of labile OM/C
and enhanced remineralisation by microbes. 4. Synthesis and applications:
This study provides empirical evidence that small-scale shading-induced
seagrass die-offs can reduce seagrass carbon sequestration capacity and
trigger losses of blue carbon stocks. While the losses recorded here are
modest, these losses in blue carbon storage capacity are notable due to
the proximity of shading structures (for example, boat docks) to seagrass
habitats. Thus, policies to avoid or protect seagrass habitats from common
small-scale, shading disturbances are important for optimising both carbon
sequestration capacity and coastline development and
management.17-Nov-2017

1. 海草床（seagrass meadows）是全球重要的蓝碳汇（blue carbon sinks）。尽管过去一个世纪全球海草资源流失达30%，但针对海草受干扰及消失对蓝碳储量影响的实证研究仍较为匮乏。
2. 本研究提出假说：海草消失会降低蓝碳储量。研究人员利用遮光布模拟了墨西哥湾北部动态泻湖中的两种亚热带海草物种——海菖蒲（Halodule wrightii）和泰莱藻（Thalassia testudinum）的小规模枯萎现象。在枯萎处理前、处理后不久以及处理后11个月三个时间节点，分别对比了枯萎区、对照组与裸地区的沉积物有机质与有机碳的数量与质量变化。在处理后11个月时，研究人员对裸地区和泰莱藻样地开展了铅210（210Pb）年代测定，以评估无植被覆盖时的沉积物侵蚀影响。
3. 小规模枯萎现象导致海菖蒲样地0~8cm沉积物中的有机质（OM）流失50%~65%。泰莱藻样地仅在表层1cm沉积物中就出现了显著的有机质流失（50%）与有机碳流失（21%~47%）。铅210剖面分析显示，泰莱藻枯萎不仅造成了约1年固存碳储量的损失（约22 g·m⁻²），还使碳固存速率降低了10%。此外，有机质质量分析结果表明，易降解有机质/有机碳（labile OM/C）发生流失，且微生物的再矿化作用增强。
4. 综合与应用：本研究通过实证证实，遮光诱导的小规模海草枯萎会削弱海草的碳固存能力，并引发蓝碳储量损失。尽管本研究记录的损失幅度较为有限，但由于遮光结构（如船坞）紧邻海草栖息地，此类蓝碳储碳能力的损失仍不容忽视。因此，制定政策以避免或保护海草栖息地免受常见的小规模遮光干扰，对于优化碳固存能力以及海岸线开发与管理均具有重要意义。2017年11月17日