Trophic Status and Ecosystem Functioning of Tropical Lake Tinshu Abaya, Ethiopia: A Mass‐Balance Modeling Approach

Freshwater ecosystems are highly susceptible to degradation, underscoring the importance of assessing their health using ecological indicators. In this study, we developed an Ecopath mass‐balance model for Lake Tinshu Abaya, Ethiopia, and analyzed its trophic structure and energy flows. The model integrated seven functional groups using data on fish catch, diet composition, and plankton biomass collected from March to August 2022. The seven functional groups were detritus, phytoplankton, herbivorous zooplankton, carnivorous zooplankton, zoobenthos, Nile Tilapia ( Oreochromis niloticus ), and birds. Four trophic levels were determined, ranging from 1.00 for primary producers and detritus to 3.56 for birds of prey. The calculated values for the EE of the primary producers (phytoplankton: 0.87; detritus: 0.75) indicated that they were highly exploited compared to the secondary producers, the herbivorous zooplankton (0.40), the carnivorous zooplankton (0.065), and the zoobenthos (0.60). The computed primary production to total respiration ( P / R ) ratio of 1.19 suggested that the ecosystem is in a developing, net autotrophic state. The ecosystem exhibited a high degree of internal recycling (Finn's Cycling Index = 15.2%), reflecting efficient energy and nutrient utilization. The trophic connectivity index of 0.56 suggested a moderately interconnected food web. Collectively, these metrics indicate that Lake Tinshu Abaya is a developing ecosystem in a transitional stage, not yet having reached full ecological maturity.