Preliminary Observations on the Diversity and Abundance of Aquatic Macroinvertebrate Fauna of Kashimbila Reservoir and Its Environs, Taraba State, Nigeria

Abstract

The Kashimbila Reservoir, created through the damming of River Katsina-Ala and 
commissioned in 2023, represents a major multipurpose water resource project in northern 
Nigeria. Designed primarily to generate hydroelectric power, it also provides potable water 
to surrounding communities, supports irrigation, sustains fisheries, promotes tourism, and 
serves as a safeguard against the potential collapse of Lake Nyos by capturing discharged 
waters. Understanding the ecological status of this newly established reservoir is crucial, 
particularly through the study of macroinvertebrates, which play key roles in aquatic food 
webs and serve as reliable bioindicators of water quality. While extensive information exists 
on macroinvertebrate assemblages in southern Nigeria, there is a paucity of comparable data 
for northern freshwater ecosystems, especially the Kashimbila Reservoir. This study 
investigated macroinvertebrate communities over a six-month sampling period using a 500 µm 
mesh dip-net. Collected specimens were identified based on morphological characteristics 
with reference to standard taxonomic keys, and community structure was assessed using 
diversity indices calculated in PAST3 software. Three invertebrate phyla were recorded: 
Annelida, Arthropoda, and Mollusca, distributed across four classes. Class Clitellata 
(Annelida) accounted for 6.6% of the total abundance, Malacostraca (Arthropoda) for 7.4%, 
Insecta (Arthropoda) for 34.6%, and Gastropoda (Mollusca) dominated the assemblage with 
51.3%. Diversity analysis revealed a Shannon–Wiener index of 2.13 and a Margalef’s richness 
index of 1.70, both indicating relatively low species diversity and richness within the 
reservoir. These findings provide the first baseline ecological data on macroinvertebrate 
fauna in the Kashimbila Reservoir, establishing a foundation for long-term monitoring and 
management of the ecosystem. Given the reservoir’s socio-economic and ecological 
importance, future studies should adopt a more comprehensive approach by incorporating 
seasonal variations and examining the influence of physicochemical parameters on both 
littoral and benthic macroinvertebrate communities. Such investigations will be critical for 
informing sustainable management practices and ensuring the ecological integrity of this 
strategic water resource.