Twice each day, tides ebb and flow through a maze of sandy channels, mudflats, and mangrove forests that flank the 88 islands and islets of Guinea-Bissau’s Bijagós Archipelago (Arquipélago dos Bijagós in Portuguese). Seen from above, the process leads to stark changes to the landscape: around low tide, intertidal mudflats and sandflats emerge from the sea, causing islands to grow significantly before shrinking again hours later.
潮汐每天两次涨落，流经几内亚比绍 Bijagós 群岛（葡萄牙语为 Arquipélago dos Bijagós）88 个岛屿和小岛两侧的迷宫般的沙质河道、泥滩和红树林。从上面看，这个过程导致地貌发生了明显的变化：退潮时，潮间带泥滩和沙滩从海上出现，导致岛屿显着增大，几小时后又再次缩小。
The perpetual rhythm of the tides sustains outpourings of marine life in an archipelago that, as of 2025, was inscribed as a UNESCO World Heritage site . The site protects the only active deltaic archipelago on Africa’s Atlantic coast, a place where tides, river sediments, coastal upwelling, and coastal currents come together to shape unusually productive and biodiverse island ecosystems.
潮汐的永恒节奏维持着群岛上海洋生物的大量繁殖，截至 2025 年，该群岛已被列入联合国教科文组织世界遗产名录。该遗址保护着非洲大西洋沿岸唯一活跃的三角洲群岛，在这里，潮汐、河流沉积物、沿海上升流和沿海洋流汇聚在一起，形成了异常多产和生物多样性的岛屿生态系统。
UNESCO estimates that the islands support some 870,000 migratory shorebirds, making this one of the most important feeding areas for birds in West Africa along the East Atlantic Flyway . Hundreds of species of birds dine on a potpourri of marine worms, crustaceans, mollusks, and small fish found on mudflats exposed by low tides. During high tides, manatees, dolphins, and schools of fish move closer to the islands, pushing deeper into the mangrove forests that ring them, and tens of thousands of sea turtles swim inland to sandy beaches as they hunt for nesting sites.
联合国教科文组织估计，这些岛屿栖息着约 87 万只候鸟，使其成为西非东大西洋迁徙路线沿线鸟类最重要的觅食区之一。数百种鸟类以低潮时暴露在泥滩上的海洋蠕虫、甲壳类动物、软体动物和小鱼为食。涨潮时，海牛、海豚和鱼群会靠近岛屿，深入周围的红树林，数以万计的海龟会游到内陆的沙滩上寻找筑巢地。
A huge population of green sea turtles nests on the tiny island of Poilão, part of the João Vieira and Poilão Marine National Park . After hatching, young turtles make perilous nighttime dashes to the water, often pursued by crabs, lizards, and birds. Once they reach the water, baby sea turtles face an array of predators, including jacks, barracudas, groupers, and snappers that patrol shallow waters as well as tuna, mackerel, sharks, and rays in deeper waters. According to some estimates, less than 1 percent of green sea turtle hatchlings survive to adulthood.
大量绿海龟在波伊朗小岛上筑巢，该岛是若昂维埃拉和波伊朗海洋国家公园的一部分。孵化后，幼龟会在夜间危险地冲入水中，经常被螃蟹、蜥蜴和鸟类追赶。一旦到达水中，小海龟就会面临一系列捕食者，包括在浅水区巡逻的鲹鱼、梭鱼、石斑鱼和笛鲷，以及在较深水域巡逻的金枪鱼、鲭鱼、鲨鱼和鳐鱼。据估计，只有不到 1% 的绿海龟幼龟能活到成年。
A 2025 analysis of the region’s tides explored why the archipelago has some of the largest tidal ranges in West Africa. The researchers concluded that the region’s wide, shallow shelf and the estuary’s geometry combine to create a tidal range of up to 7 meters (23 feet), compared to about 1 meter (3 feet) in many other parts of the West African coast. The scientists used altimetry data from the NASA/CNES TOPEX/Poseidon , Jason-1 , and Jason-2 satellites to help validate their findings.
2025 年对该地区潮汐的分析探讨了为什么该群岛拥有西非最大的潮差。研究人员得出结论，该地区宽而浅的陆架和河口的几何形状相结合，产生了高达 7 米（23 英尺）的潮差，而西非海岸许多其他地区的潮差约为 1 米（3 英尺）。科学家们使用来自 NASA/CNES TOPEX/Poseidon 、Jason-1 和 Jason-2 卫星的测高数据来帮助验证他们的发现。
NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey . Story by Adam Voiland.
NASA 地球观测站图像由 Lauren Dauphin 使用美国地质调查局的陆地卫星数据拍摄。亚当·沃伊兰的故事。