Understanding the impacts on the Brazilian semi-arid coast, which is a drought-prone area (>1000 km) in the tropical Atlantic, and how ecosystems survive and adapt to such extreme environments requires socioecological studies to create a theory for conservation. Here, we highlight five main ongoing changes in tropical semi-arid areas, namely (1) the decrease in rainfall rates due to climate change, which alters freshwater flows, alters water residence times, and promotes hypersalinity (>37) in low-inflow estuaries; (2) sea-level rise, groundwater hazards, increased erosion of beaches and nearshore mangroves, and landward mangrove forest expansion due to enhanced saline intrusion along river basins; (3) the decrease in land-ocean fluxes due to silting and closure of sandy bars in estuarine mouths; (4) warming and increased intensity and frequency of extreme events (e.g., heat waves, droughts, and sea swells); and (5) growing eutrophication and hypoxia, loss of vegetation cover and biodiversity due to urbanization, aquaculture (shrimp farming), agriculture, and land-use change, which includes building dams for water supply. The alteration of biogeochemical processes (“Arctic Paradox” hypothesis) and acidification that potentialize the impact of contaminants and nutrients is also highlighted. These impacts have effects on food and water security and multiple trophic levels, which should preferentially be studied through a long-term approach for advancing research. Based on these concerns, we propose key questions that should guide research in the context of the Decade of Ocean Science for Sustainable Development (2021–2030) to support science-based management actions in Brazil and other similar semi-arid areas worldwide.

了解对巴西半干旱海岸的影响，这是热带大西洋的干旱多发区（> 1000 公里），以及生态系统如何生存和适应这种极端环境需要社会生态学研究来创建保护理论。在这里，我们强调了热带半干旱地区的五个主要持续变化，即（1）气候变化导致降雨率下降，这改变了淡水流量，改变了水的停留时间，并促进了低流入地区的高盐度（>37）河口；(2) 海平面上升、地下水危害、海滩和近岸红树林侵蚀加剧，以及由于沿江流域的盐分入侵加剧而向陆上红树林扩张；(3) 河口河口沙坝淤塞和关闭导致海陆通量减少；(4) 变暖以及极端事件（如热浪、干旱和海浪）的强度和频率增加；(5) 城市化、水产养殖（养虾）、农业和土地利用变化（包括修建供水大坝）导致的富营养化和缺氧日益严重、植被覆盖和生物多样性丧失。生物地球化学过程的改变（“北极悖论”假说）和酸化可能会影响污染物和营养物质的影响也得到了强调。这些影响对粮食和水安全以及多种营养水平产生影响，应优先通过长期方法进行研究以推进研究。基于这些担忧，