Fish community dynamics of seasonal rivers of the Incomati Basin, Kruger National Park, South Africa

Abstract

Seasonal rivers play a critical role in shaping aquatic ecosystems and provide essential ecosystem services in freshwater systems. Due to a limited understanding of seasonal rivers and how ecological indicators such as fish communities are structured, it is important to identify flagship species and understand fish community dynamics as ecological indicators in these poorly understood systems. The study aimed to investigate the diversity of fish communities and assess the general community structure within seasonal rivers of the southern Kruger National Park. Fish were sampled using a multi-method approach in the Biyamiti, N’waswitsontso and Nsikazi rivers between January 2020 and August 2021. Study results indicated a high fish species richness, but low abundance, particularly during the winter months due to unique ecological and hydrological conditions. The dominant fishes were Oreochromis mossambicus, Enteromius trimaculatus, Micralestes acutidens, Enteromius viviparus, Brycinus imberi and Labeo ruddi. Understanding the influence of seasonality, predictability, and spatiotemporal dynamics of physico-chemical variable oscillations on fish diversity will provide a clearer understanding of their community structure and enable the better management of these fish species and associated river systems.