Is environmental legislation conserving tropical stream faunas? a large-scale assessment of local, riparian and catchment-scale influences on Amazonian stream fish

1.Agricultural expansion and intensification are major threats to tropical biodiversity. In addition to the direct removal of native vegetation, agricultural expansion often elicits other human-induced disturbances, many of which are poorly addressed by existing environmental legislation and conservation programmes. This is particularly true for tropical freshwater systems, where there is considerable uncertainty about whether a legislative focus on protecting riparian vegetation is sufficient to conserve stream fauna. 2.To assess the extent to which stream fish are being effectively conserved in agricultural landscapes, we examined the spatial distribution of assemblages in river basins to identify the relative importance of human impacts at instream, riparian, and catchment scales, in shaping observed patterns. We used an extensive dataset on the ecological condition of 83 low-order streams distributed in three river basins in the eastern Brazilian Amazon. 3.We collected and ide...1. 农业扩张与集约化是威胁热带生物多样性的主要因素。除直接移除本土植被外，农业扩张往往还会引发其他人为干扰，而现有环境立法与保护计划大多难以应对这类干扰。这一情况在热带淡水生态系统中尤为突出，目前学界仍存在较大不确定性：仅依靠以保护河岸植被（riparian vegetation）为核心的立法手段，是否足以保护溪流动物群落。 2. 为评估农业景观中溪流鱼类的有效保护程度，本研究通过调查流域内物种集合的空间分布特征，明确了溪流内部、河岸与集水区尺度的人为干扰对观测到的群落格局的相对影响权重。本研究依托一套涵盖巴西亚马孙东部三个流域内83条低等级溪流生态状况的大型数据集。 3. 我们采集并……（原文此处截断为ide...）