Application of phytoplankton community structure for ranking the major riverine catchments influencing the pollution status of a lake basin

Abstract

The present study demonstrates the application of a multi‐metric Phytoplankton Index of Biotic Integrity (PIBI) approach for ranking of major river catchments in the Kenyan part of Lake Victoria on the basis of their pollution status. The index utilizes water quality and zooplankton data, phytoplankton diversity, abundance and attributes, as well as literature information. The rivers were sampled from 2016 to 2018 during the wet season (March) and dry season (July). The separation power of the Mann–Whitney U test (p < .05) qualified eight discriminant metrics for phytoplankton samples into a scoring system of 1, 3 and 5, based on high, fair and slight deviation from the best site, respectively, in development of the final PIBI. The Kuja and Sondu‐Miriu rivers had the highest PIBI, signifying least pollution influence on the lake. In contrast, the Yala and Nzoia rivers exhibited the lowest PIBI, representing the catchments with a higher pollution influence on the lake. The fair to poor integrity classes for the major river catchments in the region signified a deteriorating lakescape. The present study presents the preliminary results of using phytoplankton metrics for development of the Index of Biotic Integrity (IBI) approach in the region as a decision‐making support tool for the effective management and sustainable use of water resources in the lake basin.

Citizen Science for Bio-indication: Development of a Community-Based Index of Ecosystem Integrity for Assessing the Status of Afrotropical Riverine Ecosystems

“…The interview questions were then coded and summary tables and figures produced for the various responses. In order to ascertain the degree of accuracy of the CIEI in determining the pollution status of the sampled ecosystem, previously developed Phytoplankton Index of Biotic Integrity (PIBI) values in similar study sites were used for the validation of the novelty approach (Aura et al, 2020). The similarity of the study sites would help establish the degree of performance and robustness of the CIEI as a citizen-led tool in relation to the previous PIBI developed as a scientific-led output.…”

“…In working toward the protection of freshwater ecosystems, development of decision-support tools for monitoring changes in water quality and biological communities over time has been given a priority in many parts of the world (Statzner et al, 2001;Aura et al, 2020;Ko et al, 2020). Biological communities have especially become common indicators of change, based on the premise that the presence or absence of certain species or groups of species at a given site reflects its environmental quality (Barbour et al, 1999;Dallas et al, 2010).…”

Exploring the potential of small water bodies as an integrative management tool for fisheries production

“…Optimal levels of nutrients (nitrogen and phosphorus) are important for autotrophic productivity that forms the primary source of energy for the heterotrophic predators (Aura et al, 2020). Elevated or reduced nutrient levels would lead to a shift in habitat characteristics with consequential impact on biotic health, structure, abundance, and overall change to ecological processes (Masese et al, 2013).…”

“…Phytoplankton diversity and abundance reflect an SWB's ecosystem health and productivity. For example, phytoplankton is an important bio‐indicator of heavy metal pollution in aquatic ecosystems due to its capacity to eliminate them from the water and to accumulate and store them over long periods even when the concentrations in the water are low (Aura et al, 2020a; Kundu et al, 2017).…”

“…Additionally, biological productivity of any given water body can be limited by either light or nutrient availability (Aura et al, 2020a). Light irradiance in the water column would therefore be influenced by algal or suspended sediment turbidity.…”