Context

Seagrass meadows act as efficient natural carbon sinks by sequestering atmospheric CO₂ and through trapping of allochthonous organic material, thereby preserving organic carbon (C_org) in their sediments. Less understood is the influence of landscape configuration and transformation (land-use change) on carbon sequestration dynamics in coastal seascapes across the land–sea interface.

Objectives

We explored the influence of landscape configuration and degradation of adjacent mangroves on the dynamics and fate of C_org in seagrass habitats.

Methods

Through predictive modelling, we assessed sedimentary C_org content, stocks and source composition in multiple seascapes (km-wide buffer zones) dominated by different seagrass communities in northwest Madagascar. The study area encompassed seagrass meadows adjacent to intact and deforested mangroves.

Results

The sedimentary C_org content was influenced by a combination of landscape metrics and inherent habitat plant- and sediment-properties. We found a strong land-to-sea gradient, likely driven by hydrodynamic forces, generating distinct patterns in sedimentary C_org levels in seagrass seascapes. There was higher C_org content and a mangrove signal in seagrass surface sediments closer to the deforested mangrove area, possibly due to an escalated export of C_org from deforested mangrove soils. Seascapes comprising large continuous seagrass meadows had higher sedimentary C_org levels in comparison to more diverse and patchy seascapes.

Conclusion

Our results emphasize the benefit to consider the influence of seascape configuration and connectivity to accurately assess C_org content in coastal habitats. Understanding spatial patterns of variability and what is driving the observed patterns is useful for identifying carbon sink hotspots and develop management prioritizations.

中文翻译：

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红树林-海草海景中蓝色碳的动态和命运：景观配置和土地利用变化的影响

语境

海草草甸通过隔离大气中的CO ₂并捕获异源有机物质，从而作为有效的天然碳汇，从而在其沉积物中保留有机碳（C _org）。人们还不太了解景观配置和转换（土地用途的变化）对跨陆海界面的沿海海景中碳固存动态的影响。

目标

我们探索了景观结构和相邻红树林的退化对海草生境中C _org动力学和命运的影响。

方法

通过预测建模，我们评估了马达加斯加西北部不同海草群落为主的多个海景区（千米宽缓冲区）中的沉积C _org含量，储量和源组成。研究区域包括毗邻完整和砍伐的红树林的海草草甸。

结果

沉积C _org含量受景观指标和固有生境植物和沉积物特性的组合影响。我们发现很可能是由水动力推动的海陆梯度很强，在海草海景中的沉积C _org水平产生了不同的模式。有较高的C_的有机含量和海草表面沉积物红树信号更靠近采伐红树区，可能是由于C的升级出口_组织从采伐红树林的土壤。与更多样化和不完整的海景相比，包括大型连续海草草甸的海景具有较高的沉积C _org水平。

结论

我们的结果强调了考虑海景配置和连通性的影响以准确评估沿海生境中C _org含量的好处。了解可变性的空间模式以及导致观测模式变化的因素，对于识别碳汇热点和制定管理优先级很有用。