Using the Biological Condition Gradient Model as a Bioassessment Framework to Support Rehabilitation and Restoration of the Upper Tana River Watershed in Kenya

Abstract

The biological condition gradient (BCG), a scientific framework that describes the change in ecosystem characteristics in response to human-induced levels of stressors, was modified and used to characterize watershed habitats in the Upper Tana River watershed, Kenya. The inbuilt utilities of BCG, including its simplicity, versatility, and its robust nature, allowed its use by seven taxonomic groups of macroinvertebrates, diatoms, fish, herpetofauna (amphibians and reptiles), plants, macrofungi, and birds to assess and monitor landscape conditions in both terrestrial and aquatic habitats. The biological data were described using taxa abundance distribution measures followed by multivariate analyses to determine their relationship with water or soil quality and thereafter assessment of taxa tolerant levels in response to environmental stress and disturbances. Preliminary findings reported that the taxonomic groups complemented each other, with each taxonomic group reliably assessing ecological conditions to a certain degree that supported assigning all 36 sampled sites into BCG tiers. The BCG models developed for all taxonomic groups assisted in the identification and selection of taxa indicating varying levels of landscape conditions. These taxa, referred to as flagship or indicator taxa, assist in simplifying the BCG model and, hence, are possible for use by parataxonomists or ordinary citizens to assess and monitor the ecological health of habitats under consideration. Furthermore, the capability of BCG models to assess landscape conditions shows how they can be used to identify important habitats for conservation, direct investment for restoration, and track progress.

Impacts of Land Use Types on Shallow Groundwater Quality Sources in Mathira East Sub-County in Kenya

“…The increasing quantities of turbidity and conductivity in water directly corresponded to the increasing gradient of landscape disturbances from forest to urban areas. Degraded landscapes are major sources of sediments that are easily eroded and transported by surface and subsurface water ows to lowland areas where wetlands and shallow groundwater resources are generally located (Ndiritu et al, 2021). Also, degraded soils allow constituents of organic and inorganic fertilizers to percolate and reach groundwater sources (Storger & Van Allen, 2014).…”

Biomonitoring for Watershed Protection from a Multiscale Land-Use Perspective

“…For example, the first MMI/IBI for assessing rivers was developed to evaluate the United States' water condition, as highlighted by the Clean Water Act of 1972 [132]. Studies and national control agencies worldwide have adopted the MMI/IBI [45,133] for use to assess macroinvertebrates, diatoms, and fish [79]. However, it is difficult to identify the metric's sensitivity to anthropogenic impact because it can also be affected by natural gradients such as altitude, precipitation, and temperature, among others [134].…”