Department of Animal and Environmental Biology, Delta State University, P.M.B. 1, Abraka, Nigeria.
Environ Monit Assess. 2012 Oct;184(10):6449-61. doi: 10.1007/s10661-011-2432-9. Epub 2011 Dec 2.
Canopy cover is well known to influence the distribution of macroinvertebrates in temperate streams. Very little is known about how this factor influences stream communities in Afrotropical streams. The effects and possible interactions of environmental factors and canopy cover on macroinvertebrate community structure (abundance, richness, and diversity) were examined in four stations in Eriora River, southern Nigeria bimonthly from May to November 2010. The river supported diverse macroinvertebrates in which the upstream sampling stations with dense canopy cover were dominated by Decapoda, Ephemeroptera, Odonata, Gastropoda, Trichoptera, and Coleoptera while Diptera and Coleoptera were the benthic organisms found predominant at downstream stations with less canopy cover. Some caddisfly species such as Agapetus agilis, Trichosetodes species and the stonefly Neoperla species were present upstream and were found to be potential bioindicators for a clean ecosystem. The blood worm Chironomus species and Tabanus sp. were abundant at the downstream of the river and are considered potential bioindicators for an organically degrading ecosystem. Some environmental factors varied temporally with significantly higher macroinvertebrate abundance and richness in May. We found out that canopy cover and environmental factors affected macroinvertebrates abundance, diversity, and richness and that the individual taxon had varying responses to these factors. These results help identify the mechanisms underlying the effects of canopy cover and other environmental factors on Afrotropical stream invertebrate communities.
林冠覆盖层众所周知会影响温带溪流中大型无脊椎动物的分布。然而，对于这个因素如何影响非洲热带溪流中的溪流群落，我们知之甚少。本研究于 2010 年 5 月至 11 月间，每两个月在尼日利亚南部的埃里奥拉河的四个站位，调查了环境因子和林冠覆盖层对大型无脊椎动物群落结构（丰度、丰富度和多样性）的影响及可能的相互作用。该河流支持着丰富多样的大型无脊椎动物，其中上游采样站位林冠覆盖茂密，以十足目、蜉蝣目、蜻蜓目、腹足纲、毛翅目和鞘翅目为主；而在下游林冠覆盖较少的站位，则以双翅目和鞘翅目为优势底栖生物。一些石蚕科物种，如 Agapetus agilis、Trichosetodes 属和石蝇 Neoperla 属，分布于上游，是清洁生态系统的潜在生物指标。而摇蚊科的 Chironomus 属和虻科的 Tabanus 属在河流下游丰富度较高，被认为是有机降解生态系统的潜在生物指标。一些环境因子随时间变化，5 月大型无脊椎动物丰度和丰富度明显更高。我们发现，林冠覆盖和环境因子影响大型无脊椎动物的丰度、多样性和丰富度，并且各分类单元对这些因子的响应存在差异。这些结果有助于确定林冠覆盖和其他环境因子对非洲热带溪流无脊椎动物群落影响的机制。
