Analysis of Spatial and Temporal Distribution of Aquatic Macroinvertebrates in Relation to Selected Environmental Parameters along Nairobi River, Kenya

Abstract

Aquatic diversity in riverine ecosystems is threatened by the intensification of unsustainable human actions in the river catchment areas. Nairobi River is one of the global wetlands that is experiencing high levels of degradation and this has a detrimental effect on the community's livelihood. The study aimed to analyze the spatial and temporal distribution of aquatic macro invertebrates in relation to some environmental parameters in the Nairobi River watershed in Kenya.  The study objectives were: to find out macroinvertebrates' diversity in the Nairobi River; to investigate selected water quality parameters in rainy and dry periods along the river; and to analyze the spatial distribution of macroinvertebrates in relation to selected water quality parameters. During the dry days, temperature, electrical conductivity, total dissolved solids, turbidity nitrates, and phosphates had significant differences (P ˂0.05 and F˃1). In the same period, macroinvertebrates were higher in the middle course 1 section of the river (mean 657.00) and in the middle course 2 section (mean 588.00) to upper and lower sections. However, there was no significant difference (P > .05) in the sites. Similarly, during the wet days, macroinvertebrates were noted to be higher in the middle course 2 areas (mean 168) and middle course 1 (mean 155). However, the number of macroinvertebrates was not significantly different (P > .05). Animals such as midge larvae and pupa, aquatic earthworms and mosquito larvae were highly tolerant to pollution due to adaptations to survival while others such as water penny, gilled snails, fingernail clam were sensitive to pollution thus they survived in very few sections of the river and in small numbers. The study recommends the need to conserve the river watershed as well as restore degraded river sections to guarantee the continued future provision of ecosystem services to the adjacent urban river communities and improve the river's biological integrity.