School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, United States.
Biological and Environmental Sciences, University of Stirling, Stirling, Scotland, United Kingdom.
PeerJ. 2022 Apr 29;10:e13180. doi: 10.7717/peerj.13180. eCollection 2022.
As ecosystem engineers, the construction of dams by beavers alters stream habitat physically and biologically, making them a species of interest for habitat restoration. Beaver-created habitat changes affect a wide range of aquatic invertebrate species. However, despite numerous individual studies of how beavers affect aquatic macroinvertebrate assemblages, there has been no evaluation of the consensus of these effects across studies.
We collated and examined studies comparing beaver-created ponds to nearby lotic reaches to determine general trends in aquatic macroinvertebrate richness, density, biomass, and functional composition between habitats. From this evidence, we highight knowledge gaps in how beaver activity affects aquatic macroinvertebrates.
Overall, in the majority of studies, aquatic macroinvertebrate richness was higher in nearby lotic reaches compared to beaver-created ponds, but richness at coarser scales (gamma diversity) increased with the addition of beaver ponds due to increased habitat heterogeneity. Functional feeding group (FFG) patterns were highly context-dependent, though predator taxa were generally more abundant in beaver ponds than adjacent lotic reaches. Site-specific geomorphological changes, coupled with dam or riparian zone characteristics and resulting differences in basal food resources likely shape other FFG responses.
We identify a lack of long-term studies at single or multiple sites and conclude that fine-scale approaches may improve our understanding of the dynamics of macroinvertebrates within the freshwater realm and beyond. Due to the context-dependent nature of each study, further systematic studies of beaver engineering effects across a wider variety of environmental conditions and wetland types will also help inform land and species management decisions, such as where to prioritize protection of beaver habitats in the face of a global freshwater biodiversity crisis, or where to restore beaver populations to deliver maximum benefit.
作为生态系统工程师，海狸筑坝会从物理和生物两方面改变溪流生境，使它们成为生境恢复的关注物种。海狸创造的生境变化会影响广泛的水生无脊椎动物物种。然而，尽管有许多关于海狸如何影响水生大型无脊椎动物群落的单独研究，但还没有评估这些研究结果的共识。
我们整理和检查了比较海狸创建的池塘和附近的流水段的研究，以确定栖息地之间水生大型无脊椎动物丰富度、密度、生物量和功能组成的一般趋势。从这些证据中，我们强调了海狸活动如何影响水生大型无脊椎动物的知识空白。
总体而言，在大多数研究中，与海狸创建的池塘相比，附近的流水段的水生大型无脊椎动物丰富度更高，但由于栖息地异质性增加，粗尺度（伽马多样性）的丰富度随着海狸池塘的增加而增加。功能摄食群（FFG）模式高度依赖于上下文，尽管捕食者类群在海狸池塘中通常比相邻的流水段更为丰富。特定于地点的地貌变化，加上水坝或河岸带特征以及由此产生的基础食物资源差异，可能会影响其他 FFG 的响应。
我们发现缺乏单一或多个地点的长期研究，并得出结论，精细尺度的方法可能会提高我们对淡水领域和其他领域内大型无脊椎动物动态的理解。由于每项研究的上下文依赖性，在更广泛的环境条件和湿地类型下进行更系统的海狸工程效应研究，也将有助于为土地和物种管理决策提供信息，例如在全球淡水生物多样性危机面前，在哪里优先保护海狸栖息地，或者在哪里恢复海狸种群以获得最大效益。
