ECOMORPHOLOGY AND HETEROGENEITY OF FISH SPECIES IN ASEJIRE DAM, OYO STATE NIGERIA

Abstract

Understanding the morphological diversity of fish species within an ecosystem provides critical insights into the mechanisms of ecological interactions, adaptive strategies, and evolutionary processes. This study assessed the ecomorphological traits underlying fish assemblage in Asejire Reservoir. Random samples of fish were purchased from the landing sites of fishermen from Asejire Reservoir from November 2021 to April 2022. Fish species were identified, and counted, and morphological traits associated with allometric size, ecomorphology, swimming dynamic, and feeding habits were recorded. Data were subjected to descriptive statistics, diversity indices, and multiple-factor analysis. Thirteen species (n = 96) across 10 families were encountered at Asejire. Chrysichthys nigrodigitatus was the most prevalent species, comprising 22.92% of the assemblage, while Parachanna obscura was the least represented, constituting only 1.04%. The average Simpson dominance value of 0.21 (<1) suggests moderate species diversity, validated by the Shannon-Weiner index of 1.9. Multiple Factor Analysis (MFA) revealed 12 dimensions (Dim) explaining 100% variability in the dataset. Dimensions 1 (25.44%) and 2 (12.54) accounted for 47.89% inertia and identified feeding habits (herbivore, carnivore, and omnivore) as the most critical driver of species segregation, mediated by allometric size and swimming dynamics. The elongated-deep dichotomy provided a fundamental basis for the ecomorphological interpretation of these dimensions. This study provides a key aspect of understanding and preserving the complex interactions and diversity within Asejire ecosystems, ensuring their long-term sustainability and resilience