Integrated assessment of ecosystem services, environmental threats, and management of Lake Hayq, a UNESCO ecohydrology demonstration site in Ethiopia

Abstract

Lakes provide essential ecosystem services, yet many tropical lakes are increasingly threatened by anthropogenic pressures and environmental change. Despite its ecological importance and recent designation as a UNESCO Ecohydrology Demonstration Site, Lake Hayq lacks an integrated assessment linking ecosystem services, environmental threats, ecological change, and management. This study addressed this gap by integrating household surveys across six kebeles adjacent to Lake Hayq (the smallest administrative units in Ethiopia), focus group discussions, key informant interviews, field observations, and Landsat 8/9 remote sensing (2015–2024). Ecosystem services were identified based on respondents' reporting frequency. Fisheries, drinking water and grasses for livestock feed, ceremonial grasses were the most frequently reported ecosystem services. The lake is increasingly threatened by interacting pressures, including siltation, invasive aquatic plants, overfishing, pollution, and buffer-zone encroachment. Remote sensing detected a significant decline in lake surface area (0.70 ha yr⁻¹). The locally evaluated three-band difference algorithm (3BDA; R² = 0.64) estimated chlorophyll-a concentrations of 4.15–5.55 μg L⁻¹, with localized enrichment near river inflows and shoreline areas, indicating increasing ecological stress. By integrating socio-economic evidence with Earth observation, this study provides the first holistic assessment of Lake Hayq and an evidence base for adaptive management of tropical lake ecosystems.