School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
Núcleo de Teoria e Pesquisa do Comportamento, Universidade Federal do Pará, Rua Augusto Correa 01, Guamá, 66075-110 Belém, Brazil; Department of Migration, Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315 Radolfzell, Germany; CESAM - Centro de Estudos do Ambiente e do Mar, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
Sci Total Environ. 2022 Aug 25;836:155679. doi: 10.1016/j.scitotenv.2022.155679. Epub 2022 May 3.
Saltwater intrusion can dramatically transform coastal ecosystems, changing vegetation and impacting wildlife and human communities who rely on these natural resources. This phenomenon is difficult to measure over large and remote areas but can be inferred from changes in the distribution of salt-tolerant vegetation, such as mangroves, observable from satellite imagery. The northern coast of Brazil has the largest continuous mangrove forest in the world and very low human occupation. Even so, saltwater intrusion and changes to the coastline have been reported in this region, with potential consequences for mangrove carbon storage and for local livelihoods, but this has not been quantified due to the remoteness of the area. This study measured changes in mangrove distribution along the Northern Brazil coast in the state of Amapá, covering ca. 15,000 km, over the last 38 years using Landsat satellite imagery. We found that mangrove area in this region is highly dynamic, with significant gains and losses occurring over the study period, but with an overall net gain of 157 km. Mangroves have been systematically expanding inland and this growth has accelerated close to the shoreline and at the head of tidal channels in the last two decades, indicating rapid and large-scale saltwater intrusion in this region. This phenomenon is likely driven by sea level rise, which also accelerated in this region in recent decades, but anthropogenic impacts such as buffalo grazing may also play an important role.
海水入侵会极大地改变沿海生态系统，改变植被，并影响依赖这些自然资源的野生动物和人类社区。这种现象在大面积和偏远地区很难测量，但可以从耐盐植被（如红树林）的分布变化中推断出来，这些变化可以从卫星图像中观察到。巴西北部沿海拥有世界上最大的连续红树林，人类居住密度很低。即便如此，该地区仍有报道称海水入侵和海岸线变化，这可能对红树林的碳储存和当地生计产生影响，但由于该地区偏远，尚未对此进行量化。本研究使用 Landsat 卫星图像测量了过去 38 年来巴西亚马孙州北部沿海地区约 15000 公里长的红树林分布变化。我们发现，该地区的红树林面积变化非常活跃，在研究期间发生了显著的增减，但总体上净增了 157 平方公里。红树林一直在向内陆系统地扩张，这种增长在过去二十年中在靠近海岸线和潮汐通道的头部加速，表明该地区正在发生快速和大规模的海水入侵。这种现象可能是由海平面上升驱动的，该地区最近几十年海平面也在加速上升，但水牛放牧等人为影响也可能发挥重要作用。
