Department of Biology, Faculty of Marine and Environmental Sciences, University of Cadiz, Puerto Real, Cádiz, Spain.
Centre of Marine Sciences of Algarve (CCMAR), University of Algarve, Faro, Portugal.
J Environ Manage. 2022 Nov 15;322:115841. doi: 10.1016/j.jenvman.2022.115841. Epub 2022 Aug 29.
Seagrass meadows, through their large capacity to sequester and store organic carbon in their sediments, contribute to mitigate climatic change. However, these ecosystems have experienced large losses and degradation worldwide due to anthropogenic and natural impacts and they are among the most threatened ecosystems on Earth. When a meadow is impacted, the vegetation is partial- or completely lost, and the sediment is exposed to the atmosphere or water column, resulting in the erosion and remineralisation of the carbon stored. This paper addresses the effects of the construction of coastal infrastructures on sediment properties, organic carbon, and total nitrogen stocks of intertidal seagrass meadows, as well as the size of such stocks in relation to meadow establishing time (recently and old established meadows). Three intertidal seagrass meadows impacted by coastal constructions (with 0% seagrass cover at present) and three adjacent non-impacted old-established meadows (with 100% seagrass cover at present) were studied along with an area of bare sediment and two recent-established seagrass meadows. We observed that the non-impacted areas presented 3-fold higher percentage of mud and 1.5 times higher sedimentary organic carbon stock than impacted areas. Although the impacted area was relatively small (0.05-0.07 ha), coastal infrastructures caused a significant reduction of the sedimentary carbon stock, between 1.1 and 2.2 Mg OC, and a total loss of the carbon sequestration capacity of the impacted meadow. We also found that the organic carbon stock and total nitrogen stock of the recent-established meadow were 30% lower than those of the old-established ones, indicating that OC and TN accumulation within the meadows is a continuous process, which has important consequences for conservation and restoration actions. These results contribute to understanding the spatial variability of blue carbon and nitrogen stocks in coastal systems highly impacted by urban development.
海草草甸通过在沉积物中大量固存和储存有机碳，有助于缓解气候变化。然而，由于人为和自然的影响，这些生态系统在全球范围内经历了大量的损失和退化，它们是地球上受威胁最严重的生态系统之一。当一个草甸受到影响时，植被会部分或完全丧失，沉积物会暴露在大气或水柱中，导致储存的碳被侵蚀和再矿化。本文研究了沿海基础设施建设对潮间带海草草甸沉积物特性、有机碳和总氮储量的影响，以及这些储量与草甸建立时间（近期和长期建立的草甸）的关系。研究了三个受到沿海建筑影响的潮间带海草草甸（目前的海草覆盖率为 0%）和三个相邻的未受影响的长期建立的草甸（目前的海草覆盖率为 100%），以及一个裸露沉积物区域和两个近期建立的海草草甸。我们观察到，未受影响的区域的泥含量高出 3 倍，而受影响的区域的沉积物有机碳储量高出 1.5 倍。尽管受影响的区域相对较小（0.05-0.07 公顷），但沿海基础设施导致沉积物碳储量显著减少，介于 1.1 和 2.2 Mg OC 之间，并且受影响的草甸的碳固存能力完全丧失。我们还发现，近期建立的草甸的有机碳储量和总氮储量比长期建立的草甸低 30%，这表明 OC 和 TN 在草甸内的积累是一个持续的过程，这对保护和恢复行动具有重要意义。这些结果有助于理解受城市发展高度影响的沿海系统中蓝碳和氮储量的空间变异性。
