Integrating Environmental Proxies and Benthic Foraminifera to Assess Desalination Outflow Impacts in the Western Arabian Gulf

While desalination is indispensable for freshwater security in arid regions, the ecological consequences of hypersaline brine discharge remain a concern. This study assesses the environmental conditions and benthic foraminiferal response near the Al-Dur Power and Desalination Plant in Bahrain, western Arabian Gulf. By analyzing physico-chemical parameters in water and sediment along a spatial gradient, we utilized foraminiferal community composition, diversity indices, and test preservation as proxies for environmental stress. Proximal to the discharge, we observed extreme hypersalinity (above 40 psu), reduced pH, and elevated concentrations of total organic carbon and heavy metals. These conditions correspond to a significant decline in biological status: living assemblages near the outflow exhibited reduced abundance and lower Shannon diversity (less than 2) compared to reference sites (above 2). Additionally, test discoloration, a key stress indicator, affected more than 50% of specimens near the discharge, versus lower than 50% at downstream sites. Our results delineate a localized impact zone where, despite the persistence of stress-tolerant taxa such as Ammonia, Elphidium, and Peneroplis, overall biodiversity is markedly reduced. As the first record of desalination-driven impacts on foraminifera in the western Arabian Gulf, this research provides a vital baseline and emphasizes the need for targeted mitigation strategies to protect vulnerable marine ecosystems amidst expanding desalination infrastructure.