The investigation of the zooplankton community in the newly formed Ribb Reservoir, Ethiopia: the tropical highland reservoir

Understanding the composition, diversity, and abundance of the zooplankton community is crucial for better utilization of the Ribb Reservoir, as zooplankton are the second link in the food chain in aquatic systems (they are also excellent bioindicators of aquatic health, given their central food web position) and the reservoir also serves as a source of income for the fishers. Therefore, sampling including some water quality parameters was conducted twice in the four seasons: autumn, summer, spring, and winter, from September 2020 to August 2021, in the first week of September, December, February, March, May, June, and August. Most of the physicochemical parameter values recorded in this study indicated that they were within the range of standards for zooplankton community requirements. Of the 14 species identified, Mesocyclops aequatorialis similis, Thermodiaptomus galebi, and Bra-chionus angularis had the first, second, and lowest records, respectively. Species abundance showed a decrease from autumn to winter and then to spring and summer. Species richness (14), abundance (6736), Margalef's diversity index (1.48), Menhinick's diversity index (0.17), Simpson index (0.098), dominance index (0.902), Shannon index (2.47), equality index (0.934), and reciprocal Simpson index (10.2) of the species were calculated in the reservoir. Some of the proposed management measures include reservoir buffering, impact assessment of over-abstraction of water for irrigation, time series of water quality data, and the reservoir water level should be above the conduit.

Automated summary

Understanding the composition, diversity, and abundance of the zooplankton community is crucial for better utilization of the Ribb Reservoir. This study conducted sampling and calculated diversity indices to assess the zooplankton community in different seasons. The results showed that most of the physicochemical parameters met the requirements for zooplankton.