Department of Zoology and Entomology, Rhodes University, Grahamstown 6140, South Africa.
Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana.
Sci Total Environ. 2019 Dec 10;695:133910. doi: 10.1016/j.scitotenv.2019.133910. Epub 2019 Aug 14.
Protecting the structural and functional integrity of lotic ecosystems is becoming increasingly important as many ecological systems face escalating pressures from human population growth and environmental impacts. Knowledge on the functional composition of macroinvertebrates in austral temperate streams is generally lacking hindering the design and implementation of water management and restoration goals. Therefore, this study examined the effects of urban land-use activities on the benthic macroinvertebrate functional feeding guild structure among different stream orders in an austral river system (Bloukrans River) in the Eastern Cape Province of South Africa. Water quality and macroinvertebrate community data were collected across two seasons from 18 sites in two different stream order categories (i.e. 1, 2 + 3), following standard methods. We separated macroinvertebrates into functional feeding groups (FFGs), which we then used to assess the effects of riparian condition on FFG organization. Linear mixed effects model (LMM) results demonstrated that total dissolved solids (TDS), canopy cover, phosphate and channel width were the key variables that described the major sources of variation in macroinvertebrate FFGs. Based on FFG proportions, collector-gatherers were the most abundant in the Bloukrans River and represented 71.3% of the macroinvertebrate assemblages. The FFG ratios indicated that all the eighteen sites were strongly heterotrophic (i.e. streams received additional sources of energy from leaf litter and other organic matter), showed below expected linkage with riparian input and stable substrates were limited. The FFG ratios offered some insights into the overall functioning of Bloukrans River system. Our results highlight the importance of including macroinvertebrate functional diversity as a complementary approach to assess the ecological integrity in management and restoration plans of river systems.
保护流水生态系统的结构和功能完整性变得越来越重要，因为许多生态系统面临着人口增长和环境影响带来的日益加剧的压力。有关澳大利亚温带溪流中大型无脊椎动物功能组成的知识普遍缺乏，这阻碍了水管理和恢复目标的设计和实施。因此，本研究调查了城市土地利用活动对南非东开普省布卢克兰斯河流系统（Bloukrans River）不同溪流等级中底栖大型无脊椎动物功能摄食群结构的影响。按照标准方法，在两个季节，从两个不同溪流等级（即 1、2+3）的 18 个地点收集水质和大型无脊椎动物群落数据。我们将大型无脊椎动物分为功能摄食群（FFG），然后使用这些 FFG 来评估河岸条件对 FFG 组织的影响。线性混合效应模型（LMM）结果表明，总溶解固体（TDS）、冠层覆盖、磷酸盐和渠道宽度是描述大型无脊椎动物 FFG 主要变异来源的关键变量。基于 FFG 比例，收集者-收集者在布卢克兰斯河最为丰富，占大型无脊椎动物组合的 71.3%。FFG 比值表明，所有 18 个地点均表现出强烈的异养性（即溪流从落叶和其他有机物中获得额外的能量来源），与河岸输入的预期联系较弱，稳定的基质受到限制。FFG 比值为布卢克兰斯河流系统的整体功能提供了一些见解。我们的研究结果强调了将大型无脊椎动物功能多样性纳入管理和恢复河流系统生态完整性的重要性。
