Effects of Water Quality on Spatio-Temporal Diversity of Benthic Macro-Invertebrate Species along the Selected Shores of Lake Victoria, Homa-Bay County, Kenya

Abstract

Human-induced landscape alterations impact the ecological integrity of water resources by adversely affecting fresh water ecosystems, water-quality, habitat structure, flow regime, and biotic interactions. For instance fresh-water Lake Victoria continues to be affected by massive discharge of waste-waters and other pollutants from the surrounding basin which interfere with the ecological balance leading to adverse impact on benthic macro-invertebrates especially along the lake shores. The objective of this study was to investigate the effect of water quality on the diversity of benthic macro-invertebrates along the shores of Lake Victoria in Homa-Bay County, Kenya. Samples were taken at various beaches including Oluch Kimira River Mouth, Homa Bay Sewage discharge point and Mbita East of course way shoreline and examined for water quality parameters and the species diversity of benthic macro-invertebrates at monthly intervals between September 2019 and Feb 2020. The study was conducted during dry and wet seasons to help determine any changes in waste water discharges, water quality and benthic macro-invertebrates' characteristics. The results showed significant differences between various sites along the 3 different sites. During both wet and dry periods, Oluch Kimira  and Homa Bay recorded low DO levels (4.0±0.46 to 6.2±0.19) MgL-1, while Mbita East of the course way throughout the period recorded DO level of (5.6±0.23 to 7.7±0.17) MgL-1. The mean concentration of Ammonia,NH4(µgL¯¹) during the dry season was (6.32 ±.3.55 to 8.79±3.02) and during the wet season 12.16± 0.92 to 22.50 ± 0.52. The county government should implement the findings of this study, which provides baseline data for evaluating the trends in water quality and related changes in benthic-macro invertebrates biodiversity in Lake Victoria shorelines in Homa Bay County. The findings will also help in making policy decisions in order to support environmental protection in Lake Victoria.