Metabolic-Based Assessment of Restoration Strategies in Terminal Hypersaline Lakes

Lake Urmia has experienced rapid hydrogeochemical transitions and ecological disruption in recent years despite extensive restoration efforts. The Urmia Lake Restoration Program (ULRP) identifies a water level of 1274.1 m a.s.l. as an ecological threshold intended to preserve its keystone species, Artemia urmiana (AU), based solely on empirical relationships linking water level, salinity, and ecological integrity. However, this threshold does not incorporate the mechanistic physiological sensitivities of AU, whose survival, growth, and reproduction respond sharply to changes in habitat salinity. As the lake’s sole grazer of primary producers and a critical food source for migratory birds, AU plays an essential role in sustaining the vulnerable ecosystem of this region. Therefore, a more process-based understanding of how salinity affects AU is necessary to evaluate whether this empirically derived threshold can truly support the species and the broader ecosystem. In this study, we employed a species-specific Dynamic Energy Budget (DEB) model to quantify how increasing salinity affects energy allocation and life-history traits of AU. Then, these physiological outputs were integrated into a population model to evaluate salinity impacts at the population scale. As the salinity of Lake Urmia is locally variable, we combined these results with two-dimensional salinity fields derived from hydrodynamic simulations of the lake to identify suitable areas where AU can thrive. This approach offers a process-based quantitative framework for assessing restoration scenarios and guiding management strategies to avert continued ecological decline and reinforce the resilience and functionality of hypersaline lake ecosystems.