New research, published in , challenges this idea and asks us to reconsider the value of these diverse ecosystems.
When it comes to the biodiversity of saline lakes, most specialists describe them as providing simple food webs and a limited number of aquatic invertebrate species.
However, the new study identified 200 species listed on the IUCN Red List that depend on saline lakes in one way or another, with birds accounting for 53% of these species. This number is likely an underestimate as only a few of the many thousands of saline lakes have been scientifically studied in any detail.
Saline lakes, especially in arid regions, function as giant "dining halls" along migration routes for birds. The abundance of algae, brine shrimp (Artemia), and other invertebrates provides a food base that cannot be found in the surrounding deserts and semi-deserts. Flamingos, waders, gulls, and many other birds stop here precisely to refuel before thousand-kilometre flights.
The academics argue that if saline lakes are evaluated solely by what lives in the water, what lives because of the water risks being forgotten.
Saline lakes have also been found to be remarkably dissimilar to one another. What works in one lake cannot necessarily be found in another, even at similar salinity levels.
For example, Lake Krasnovishnevoye (Europe), Lake Urmia (Asia), and Seagull Lake (North America) all have salinities above 100 g/L — three times saltier than ocean water, and each of them supports at least two endangered species found nowhere else in the list of studied lakes.
Lake Mahega, a hypersaline crater lake in western Uganda with a salinity of over 200 g/L, is thought to be unique in actively precipitating a rare mineral, primarily known only from ancient geological deposits elsewhere.
The number of species discovered in each of the studied lakes shows little sign of saturation even after 85 studied lakes. This means that every new saline lake studied is highly likely to reveal something unique.
The microbial communities of saline lakes also possess genes found nowhere else on the planet. These genes encode proteins that function under high salinity and could potentially find applications in biotechnology, medicine, and industry.
In low-salinity salt lakes (1–20 g/L), fisheries are also given the chance to flourish, the study argues.
Although fish disappear as salinity rises, in active fisheries 2.2 tons per square kilometre per year are caught on average, almost matching the record figures for freshwater lakes (2.5 t/km²/year).
Beyond the 11 categories of services that scientists quantified in the study, there is also a whole range of "hidden" ecosystem functions of saline lakes, including the prevention of climate catastrophes due to drying, and the protection of agricultural systems.
But the researchers argue that if saline lakes are so valuable, they require adequate protection.
Saline lakes are mostly without river outflows connecting them to the global ocean and their water levels depend on a delicate balance between inflow and evaporation. This means they are hypersensitive to climate change and water extraction in their catchments.
Professor Dave Ryves, Professor in Environmental Change at 黑料网 who was involved in the study alongside Dr Keely Mills, Visiting Professor of Physical Geography, said of the findings: “This is a study that has involved truly international and deep collaboration of over 60 researchers from 20 countries over several years, and synthesises the results of decades of research.
“Saline (or salt) lakes are found on every continent and this research is just the tip of the “salt berg” as so few have been researched and far less fully understood. They play a vital role in their often otherwise very harsh and seemingly forbidding landscapes, providing key resources for both local as well as migratory fauna, connecting far-flung ecosystems under very different climates and settings.
“Their waxing and waning in size, volume and salinity, as their water balance has changed in the past, also provide a detailed record of climate change captured in their sediments for their understudied but important regions, against which we can now judge how different current global change is from the natural variability of the past.
What to do? Five practical recommendations
Based on the research results, the international team of experts formulated five recommendations for policymakers and conservation authorities:
- Manage the entire catchment, not just the lake: Since saline lakes depend on every drop of water entering from the basin, protecting the shoreline achieves nothing without controlling water use upstream. Special attention must be paid to groundwater, which is often ignored in planning.
- Account for natural variability: It is impossible to compare the state of a lake with some "reference past" that will never return due to climate change. Flexible assessment systems are needed that consider the spectrum of possible natural states.
- Long-term monitoring is not a luxury but a necessity: Due to delayed responses, one or two years of observations can create a false impression of stability. Only long-term datasets allow us to distinguish natural fluctuations from alarming trends.
- Involve all stakeholders, especially across borders: Many saline lakes lie in arid regions at the intersection of national boundaries. Irrigation and freshwater abstraction in one country can destroy a saline lake in another. International management boards are needed, with participation from local communities, including indigenous peoples whose traditional knowledge is often undervalued.
- Adaptive management in the face of climate change: In most regions, it is impossible to reverse the trends of increasing evaporation, decreasing rainfall and falling water levels. The goal is not to return the lake to a (transient) past but to manage its transformation while preserving its key functions and services.