Marchamalo salt flats in the Mar Menor, one of the sites studied.

Traditionally saline lakes have been considered poor ecosystems with limited biodiversity, leading them to occupy a second place on political agendas. This study, published in Nature Communications, analyzes nearly 85 saline lakes and challenges this view. The research team shows that these water bodies are not only important refuges for threatened species but also provide a wide range of benefits to society, many of which are of cultural and economic importance.

This project has been made possible thanks to a wide network of international collaboration involving 64 coauthors from 20 countries and different institutions, led by the Helmholtz Centre for Environmental Research (UFZ, Alemania) and with the participation of the Doñana Biological Station of the Spanish National Research Council (EBD-CSIC).

“One of the study’s core strengths is the direct knowledge contributed by the researchers themselves and their experience of working in different salt lakes, providing their own data rather than simply compiling existing studies,” emphasises Marta I. Sánchez, co-author and researcher at the Doñana Biological Station – CSIC.

A shelter for biodiversity

Across the 85 saline lakes studied, a total of nearly 180 species classified as threatened or near threatened by the International Union for Conservation of Nature (IUCN) were recorded. Birds accounted for more than 53% of all threatened species, highlighting the fundamental role of saline lakes as feeding, breeding, and stopover sites for migratory birds.

“We found that ecosystems with similar salinity levels can support very different species and ecological functions, with unique components of biodiversity and endemic species, highlighting the distinctiveness of these ecosystems,” explains Sánchez. “One saline lake cannot easily be replaced by another,” she adds.

Likewise, the underrepresentation of invertebrates on the Red List of Threatened Species has negative implications for the conservation of these lakes, as they are true refuges for invertebrate species. The analyses, for example, recorded nearly 500 different dominant plankton species. None of these species are currently listed as threatened, although some, such as Artemia monica and Artemia persimillis, are endemic to highly stressed ecosystems.

In Spain, the Mar Menor stands out as a refuge for numerous threatened species, including the black tern (Chlidonias niger) and the marbled teal (Marmaronetta angustirostris), both of which are classified as critically endangered. The ecosystem is also home to endemic species such as the Spanish toothcarp (Aphanius iberus), a small fish that is also threatened. Another site of great ecological value is Fuente de Piedra Lagoon in Málaga, one of the country’s main saline wetlands. It provides food and shelter for numerous bird species, including the great bustard (Otis tarda), which is classified as endangered at the global level. Aquatic plants such as Althenia orientalis, which has a highly restricted distribution and is considered highly threatened, also grow there.

Benefits to society

These ecosystems provide a range of direct and indirect benefits to society, known as ecosystem services. For example, high levels of tourism and recreational use were recorded at all the lakes studied. Fishing, salt extraction, and wastewater discharge were also identified as ecosystem services (in most cases, involving untreated wastewater). On average, each lake supported five different ecosystem services.

Although saline lakes have begun to be recognized and protected in some countries and regions, the vast majority still lack established management policies. “The value of these systems contrasts with their enormous vulnerability, as they depend on a hydrological balance that is under severe threat from climate change and water extraction within their catchments,” Sánchez points out.

The study sets out a series of recommendations to improve their management. These include considering the entire watershed and its connections, rather than limiting management measures to the lake surface alone; respecting the lakes’ natural variability, recognizing that changes in water levels and even periods of drying are part of their natural dynamics; implementing long-term monitoring programs to identify damage at an early stage; and developing adaptive management strategies to address climate change.

“Despite the quantitative and qualitative importance of these ecosystems, they continue to be undervalued, understudied, and underrepresented in research, management, and conservation agendas. Through this work, we hope to do our part to change this reality and reshape perceptions of one of the planet’s most valuable yet overlooked ecosystems,” Sánchez concludes.