Vulnerable and vital: Intermittent estuaries deserve global attention

Abstract

Intermittently open/closed estuaries provide important ecosystem services but are often overlooked in coastal–catchment research and management. These estuaries are highly vulnerable to human/climate disturbances due to their tendency to close off from the ocean, yet their processes/dynamics remain under-researched. This study maps the global distribution of at least 2,245 intermittent estuaries, whose catchments currently support 55 million people, with projections rising to 101 million by 2100. Assessing three decades of scholarly articles indicated that only 7% of these sites have been studied. Academic literature on intermittent estuaries accounted for 0.5% of the total literature on all estuaries, despite these systems representing 4–5% of the estimated total number of global estuaries. Significant research gaps exist in Asia, South America, and Africa, where the largest, most susceptible populations reside. 90% of the existing research on intermittent estuaries is conducted in (southern) Africa (42%), Oceania (35%), and North America (14%), predominantly through domestic efforts. From 1992 to 2023, 60% of the research focused on physio-chemical and eco-hydro-geomorphological topics, with minimal attention to ecosystem services, climatic/human disturbances, and management. Our assessment underscores the need for increased focus on intermittent estuaries and suggests strategies to promote international collaborations, including leadership from intergovernmental organisations.