Laboratório de Ecologia Aplicada à Conservação (LEAC), Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Rodovia Jorge Amado, Km 16, Ilhéus, BA, 45650-000, Brazil.
Center for Ecology, Evolution and Conservation, School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, NR47TJ, U.K.
Conserv Biol. 2021 Jun;35(3):870-883. doi: 10.1111/cobi.13619. Epub 2020 Nov 9.
Megadams are among the key modern drivers of habitat and biodiversity loss in emerging economies. The Balbina Hydroelectric Dam of Central Brazilian Amazonia inundated 312,900 ha of primary forests and created approximately 3500 variable-sized islands that still harbor vertebrate populations after nearly 3 decades after isolation. We estimated the species richness, abundance, biomass, composition, and group size of medium- to large-bodied forest vertebrates in response to patch, landscape, and habitat-quality metrics across 37 islands and 3 continuous forest sites throughout the Balbina archipelago. We conducted 1168 km of diurnal censuses and had 12,420 camera-trapping days along 81 transects with 207 camera stations. We determined the number of individuals (or groups) detected per 10 km walked and the number of independent photographs per 10 camera-trapping days, respectively, for each species. We recorded 34 species, and patch area was the most significant predictor of vertebrate population relative abundance and aggregate biomass. The maximum group size of several group-living species was consistently larger on large islands and in continuous patches than on small islands. Most vertebrate populations were extirpated after inundation. Remaining populations are unlikely to survive further ecological disruptions. If all vertebrate species were once widely distributed before inundation, we estimated that approximately 75% of all individual vertebrates were lost from all 3546 islands and 7.4% of the animals in all persisting insular populations are highly likely to be extirpated. Our results demonstrate that population abundance estimates should be factored into predictions of community disassembly on small islands to robustly predict biodiversity outcomes. Given the rapidly escalating hydropower infrastructure projects in developing counties, we suggest that faunal abundance and biomass estimates be considered in environmental impact assessments and large strictly protected reserves be established to minimize detrimental effects of dams on biodiversity. Conserving large tracts of continuous forests represents the most critical conservation measure to ensure that animal populations can persist at natural densities in Amazonian forests.
巨坝是新兴经济体中导致栖息地和生物多样性丧失的主要现代驱动因素之一。巴西中部亚马逊地区的巴尔比纳水电站淹没了 31.29 万公顷的原始森林，并创造了大约 3500 个大小不等的岛屿，这些岛屿在隔离近 30 年后仍然有脊椎动物种群。我们根据斑块、景观和栖息地质量指标，在巴尔比纳群岛的 37 个岛屿和 3 个连续森林地点，估计了中大型森林脊椎动物的物种丰富度、丰度、生物量、组成和群体大小。我们进行了 1168 公里的昼间普查，并在 81 条沿线上进行了 12420 天的相机陷阱，这些沿线上有 207 个相机站。我们确定了每种物种每行走 10 公里检测到的个体（或群体）数量和每 10 天相机陷阱拍摄到的独立照片数量。我们记录了 34 个物种，斑块面积是脊椎动物种群相对丰度和总生物量的最重要预测因子。一些群居物种的最大群体大小在大岛屿和连续斑块上始终大于小岛屿。大多数脊椎动物种群在淹没后灭绝。剩余的种群不太可能再遭受进一步的生态破坏。如果所有脊椎动物物种在淹没前都广泛分布，我们估计大约 75%的所有个体脊椎动物从所有 3546 个岛屿上消失，而所有持续存在的岛屿种群中，有 7.4%的动物极有可能灭绝。我们的研究结果表明，在预测小岛屿上群落解体时，应考虑种群丰度估计，以稳健地预测生物多样性的结果。鉴于发展中国家的水电基础设施项目迅速升级，我们建议在环境影响评估中考虑动物丰度和生物量估计，并建立大型严格保护区，以将大坝对生物多样性的不利影响降至最低。保护大片连续森林是确保亚马逊森林中动物种群能够以自然密度持续存在的最关键保护措施。
