Maasri Alain, Gelhaus Jon
The Academy of Natural Sciences of Drexel University, 1900 Ben Franklin Parkway, Philadelphia, PA 19103-1195, USA.
Aquat Biosyst. 2012 Aug 24;8(1):18. doi: 10.1186/2046-9063-8-18.
Mongolia's riverine landscape is divided into three watersheds, differing in extent of permafrost, amount of precipitation and in hydrological connectivity between sub-drainages. In order to assess the vulnerability of macroinvertebrate communities to ongoing climate change, we consider the taxonomic and functional structures of stream communities in two major watersheds: The Central Asian Internal Watershed (CAIW) and the Arctic Ocean Watershed (AOW), together covering 86.1% of Mongolia's surface area. We assess the consequences of the hydrological connectivity between sub-drainages on the nestedness and distinctness of the stream communities. And accordingly, we discuss the expected biotic changes to occur in each watershed as a consequence of climate change.
Gamma and beta diversities were higher in the CAIW than the AOW. High community nestedness was also found in the CAIW along with a higher heterogeneity of macroinvertebrate assemblage structure. Assemblages characteristic of cold headwater streams in the CAIW, were typical of the drainages of the Altai Mountain range. Macroinvertebrate guilds of the CAIW streams exhibited traits reflecting a high stability and low resilience capacity for eutrophication. In contrast, the community of the AOW had lower nestedness and a combination of traits reflecting higher stability and a better resilience capacity to disturbances.
Higher distinctness of stream communities is due to lower connectivity between the drainages. This was the case of the stream macroinvertebrate communities of the two major Mongolian watersheds, where connectivity of streams between sub-drainages is an important element structuring their communities. Considering differences in the communities' guild structure, hydrological connectivity and different magnitudes of upcoming impacts of climate change between the two watersheds, respective stream communities will be affected differently. The hitherto different communities will witness an increasing differentiation and divergent adaptations for the upcoming changes. Accordingly, in an increasing awareness to protect Mongolia's nature, our results encourage adapting conservation planning and management strategies specifically by watershed.
蒙古的河流地貌分为三个流域，在多年冻土范围、降水量以及子流域之间的水文连通性方面存在差异。为了评估大型无脊椎动物群落对当前气候变化的脆弱性，我们研究了两个主要流域（中亚内流水系流域（CAIW）和北冰洋水系流域（AOW））中溪流群落的分类结构和功能结构，这两个流域共覆盖了蒙古86.1%的表面积。我们评估了子流域之间的水文连通性对溪流群落嵌套性和独特性的影响。据此，我们讨论了气候变化导致的每个流域预期生物变化。
CAIW的伽马多样性和贝塔多样性高于AOW。在CAIW中还发现了较高的群落嵌套性以及大型无脊椎动物组合结构的更高异质性。CAIW中寒冷源头溪流的典型组合是阿尔泰山脉流域的典型特征。CAIW溪流的大型无脊椎动物类群表现出反映高稳定性和低富营养化恢复力的特征。相比之下，AOW的群落嵌套性较低，其特征组合反映出更高的稳定性和对干扰的更好恢复力。
溪流群落较高的独特性是由于流域之间的连通性较低。蒙古两个主要流域的溪流大型无脊椎动物群落就是这种情况，子流域之间溪流的连通性是构建其群落的重要因素。考虑到两个流域群落类群结构、水文连通性以及即将到来的气候变化影响程度的差异，各自的溪流群落将受到不同的影响。迄今为止不同的群落将见证未来变化中日益增加的分化和不同的适应性。因此，在日益重视保护蒙古自然环境的背景下，我们的研究结果鼓励根据流域具体情况调整保护规划和管理策略。
