Seagrass meadows in oceanic coral atoll settings play key roles in sediment stabilisation and biodiversity enhancement. However, seagrass is susceptible to anthropogenic disturbance including nutrient input. Here, we experimentally enriched Thalassia hemprichii meadows with N-based fertiliser in two similar reef-top settings with different recent histories of disturbance, in Laamu atoll, Maldives. Enrichment resulted in enhanced overall leaf production, but in different ways at the two sites. At the ‘more impacted’, and slightly deeper site, the dominant effect of high-nutrient treatment was growth of new leaves, but this also coincided with cyanobacteria and filamentous green-algal blooms. In contrast, the ‘less impacted’ site, leaf extension rates (tagged and new) significantly increased. Isotopic analysis confirmed fertiliser uptake into biomass. Our findings highlight that the response of seagrass to nutrient enrichment is context dependent. This study, the first of its kind in the Indian Ocean, highlights the need and opportunity for nutrient and seagrass monitoring and associated policy development.

中文翻译：

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海草是贫营养海洋珊瑚礁环境中氮富集的早期响应者


海洋珊瑚环礁环境中的海草草甸在沉积物稳定和生物多样性增强方面发挥着关键作用。然而，海草容易受到人为干扰，包括营养输入。在这里，我们在马尔代夫拉姆环礁的两个相似的礁石顶部环境中用氮基肥料实验丰富了 Thalassia hemprichii 草甸，这些珊瑚礁近期的干扰历史不同。富集导致整体叶子产量增加，但在两个地点以不同的方式。在“受影响更大”且稍深的地点，高营养处理的主要效果是新叶的生长，但这也与蓝藻和丝状绿藻大量繁殖相吻合。相比之下，“受影响较小”的位点，叶片延伸率（标记和新）显着增加。同位素分析证实肥料吸收到生物质中。我们的研究结果强调，海草对营养富集的反应取决于环境。这项研究是印度洋的首例，强调了营养物质和海草监测以及相关政策制定的必要性和机会。