Raw Data from Variation of carbon contents in eelgrass (Zostera marina) sediments implied from depth profiles.

Seagrass meadows are able to store significant amounts of organic carbon in their underlying sediment, but global estimates are uncertain partly owing to spatio-temporal heterogeneity between and within areas and species. In order to provide robust estimates, there is a need to better understand the fate of, and mechanisms behind, organic carbon storage. In this observational study, we analyse a suite of biotic and abiotic parameters in sediment cores from 47 different eelgrass (Zostera marina) beds spanning the distributional range of the Northern Hemisphere. Depth profiles of particulate organic carbon (POC) revealed three patterns of vertical distribution where POC either increased, decreased or showed no pattern with sediment depth. These categories exhibited distinct profiles of δ13C and C : N ratios, where high POC profiles had a proportionally larger storage of eelgrass-derived material whereas low POC profiles were dominated by phytoplanktonic and macroalgal material. However, high POC did not always translate into high carbon density. Nevertheless, this large-scale dataset provides evidence that the variability in organic matter source in response to natural and anthropogenic environmental changes affects the potential role of eelgrass beds as POC sinks, particularly where eelgrass decline is observed.

海草床可在其下层沉积物中储存大量有机碳，但全球有机碳储量的估算结果仍存在较大不确定性，这部分原因在于区域间、区域内部以及不同物种类群间的时空异质性。为获取可靠的碳储量估算结果，亟需更深入地解析有机碳储存的归宿及其背后的作用机制。本项观测性研究针对横跨北半球分布范围的47处鳗草（Zostera marina）床的沉积物岩芯，分析了一系列生物与非生物参数。颗粒有机碳（Particulate Organic Carbon, POC）的深度剖面呈现出三种垂直分布模式：POC含量随沉积物深度增加而升高、降低，或无明显变化规律。这三类分布模式对应着截然不同的δ¹³C同位素特征与碳氮比：高POC剖面中鳗草来源的有机碳占比更高，而低POC剖面则以浮游植物和大型藻类来源的有机质为主。不过，高POC并不总能对应较高的碳密度。尽管如此，本大型数据集仍证实：有机质来源的多样性响应自然与人为环境变化，会影响鳗草床作为颗粒有机碳（POC）汇的潜在功能，这一点在观测到鳗草出现衰退的区域尤为显著。