Background Headwater streams and small rivers within a catchment basin contribute greatly to the overall physico-chemical and biological quality of downstream larger freshwater systems; hence, there is a need to continually assess the water quality of such smaller systems. In this study, the three major tributaries (Obudu, Opa, and Esinmirin rivers) of a tropical reservoir were assessed for their water quality using some selected water and sediment parameters, as well as their macroinvertebrate faunae. Results All the measured water parameters were found to be within the recommended standards for freshwater life in the three rivers, except for PO 4 3− and dissolved oxygen in Opa River which was possibly due to anthropogenic factors. The bottom sediment of the rivers was predominantly sandy and generally low in chemical characteristics. A total of 17 species of macroinvertebrates were recorded in this study: 14 species in Obudu River, 12 species in Esinmirin River, and 11 species in Opa River. Diversity (Margalef and Shannon-Wiener) and Pielou’s evenness indices were all low and indicative of an impaired freshwater system, with the lowest indices recorded in the Esinmirin River. Some macrobenthic environmental indicators of poor water quality (e.g., Tubifex sp., Tipula sp., Chironomus sp., Bulinus globosus , and Eristalis sp.) were exclusively recorded in the Esinmirin and/or Obudu River. Conclusion The study concludes that the reservoir’s headwaters were moderately polluted and had a tendency to become severely polluted by anthropogenic activities along the rivers. Measures should be put in place to reduce environmental impact on the quality of the headwaters and by implication, the reservoir.

中文翻译：

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使用生态方法对尼日利亚 Ile-Ife 的 Opa 水库源头河流进行生物评估

背景 流域内的源头溪流和小河流对下游大型淡水系统的整体理化和生物质量有很大贡献；因此，需要不断评估此类较小系统的水质。在这项研究中，使用一些选定的水和沉积物参数及其大型无脊椎动物群对热带水库的三个主要支流（奥布杜河、奥帕河和埃辛米林河）的水质进行了评估。结果除PO 4 3− 和奥帕河中可能由人为因素引起的溶解氧外，所有测量的水体参数均在三条河流淡水生物推荐标准范围内。河流的底部沉积物主要是沙质的，化学特性普遍较低。本研究共记录大型无脊椎动物17种：奥布杜河14种，埃辛米林河12种，奥帕河11种。多样性（Margalef 和 Shannon-Wiener）和 Pielou 的均匀度指数都很低，表明淡水系统受损，最低指数记录在 Esinmirin 河。一些水质较差的大型底栖动物环境指标（例如，Tubifex sp.、Tipula sp.、Chironomus sp.、Bulinus globosus 和 Eristalis sp.）仅记录在 Esinmirin 和/或 Obudu 河中。结论 研究得出的结论是，水库源头受到了中度污染，并有被沿河人为活动严重污染的趋势。应采取措施减少环境对源头水质的影响，并暗示，