Achieving sustainable river water quality for rural dwellers by prioritizing the conservation of macroinvertebrates biodiversity in two Afrotropical streams

Motivated by the UN Global Sustainable Development Goals on achieving sustainable freshwater ecosystem, this study was undertaken to examine two important water bodies in north central Nigeria (Baka Jeba and Penyan Rivers) protected locally by the rural community and serving as sources of water supply, for biodiversity conservation and protection. The status of macroinvertebrate biodiversity as important variable in assessing the environmental health and suitability of the water quality of the rivers was evaluated for a period of 8 months, between February and September 2017 using standard methods. The mean values of Physicochemical variables recorded during the study period revealed that the nutrient loads (nitrites and phosphates levels) was relatively low for both streams as well as conductivity levels (<82 mu S/cm). Dissolved oxygen values indicated that the water bodies were well aerated with values ranging between 5.21 and 7.83 mg/l in both the dry and wet seasons. A total of 65 invertebrate taxa from 34 families in 10 orders were recorded during the study, dominated by aquatic insects with a few representation of decapods and gastropods, and Arachnids were sporadically present. The overall abundance of macroinvertebrates was not significantly different (p > 0.05) among the sampling stations with number of individuals caught ranging between 1208 and 1728 per station. Of the major faunal groups, Ephemeroptera contributed the highest percentage of individuals (>29%) in both streams. Generally, Beka Jeba Stream contained more diverse taxa of macroinvertebrates compared to Penyan Stream. The Ephemeroptera-Trichoptera-Odonata (ETO) were the dominant groups collected in the river systems indicating fairly good water quality conditions. The Chironomids and other tolerant macroinvertebrate larvae were only sporadically present. Overall, the values of the physical and chemical parameters (low BOD, low nutrient levels and high dissolved oxygen) obtained for the two rivers and the wide diversity of sensitive macroinvertebrates portends the water body to be of good quality. Therefore utmost care should be taken to conserve and preserve these species as indicators of water quality by reducing the impact of key drivers of declines in macroinvertebrate biodiversity, including habitat degradation and pollution.