Saline lakes are widespread on all continents. Since 1979, an informal international association of salt lake researchers from a variety of disciplines has sponsored a series of triennial conferences to foster scientific exchange and our understanding of saline lakes. International Society for Salt Lake Research (ISSLR, www.isslr.org ) was founded in 1994 to establish effective liaison between persons interested in any aspect of inland saline waters, to encourage these interests, and to educate the public in the scientific use, management, and conservation of salt lakes. ISSLR conferences are held triennially. The conferences are usually hosted by a local University or research institution and provide an excellent opportunity for networking among globally dispersed researchers.

The 14^th International Conference on Salt Lake Research was held online during October 18–22, 2021 and hosted in Murcia, Spain. The conference was organized by the ISSLR together with the Institute of Saltscapes and Salt Heritage (IPAISAL), an Non-Governmental Organization devoted to the research and dissemination of the natural, cultural, and human values of saltscapes based in Spain. The conference was initially planned to be held in the autumn of 2020, but the travel restrictions imposed by the COVID-19 pandemic advised to postpone it one year. As the situation had not improved much in the following months, the local organization committee agreed with the ISSLR board of directors to keep the new dates but hold the conference online.

Two hundred and three scientists attended the conference from ten different countries, as well as representatives from several local NGOs and conservation projects focused on saline lakes and saltscapes. From the very beginning, the ISSLR was very interdisciplinary, reflecting this fact, the topics covered by presentations at the conference were very broad, such as geology, physical geography, chemistry, biology, ecology, microbiology, conservation, management, and heritage. Moving the ISSLR conference online for the first time was an organizational challenge that raised questions about the feasibility of having delegates from all over the world transmitting their work at the same time via the internet and doing so from different time zones. The participants had to follow time slots that were not always convenient to them, but this seemed not to be much of a problem, and organizers, therefore, would like to thank them for their flexibility. In addition, poster presentations were done in the format of short communications, which allowed their authors to have better outreach than is usually the case for this format.

Being online created an additional difficulty for scientific discussion and developed common grounds for collaboration among participants through informal encounters common in face-to-face conferences, this would have been much easier in a live setting, but nevertheless, contacts and ideas for future research have been exchanged, both individually and at an institutional scale. Although participants have missed the opportunity to enjoy visiting the sites that had been selected for the mid- and post-conference field trips, as well as the heritage and gastronomy of the region of Murcia (Spain), holding the conference online allowed the participation of a higher number of delegates.

Publishing this special issue was also a challenge as the multidisciplinary nature of the society and the conference made it difficult to host all qualified presentations as papers in a thematic journal. Nevertheless, the selection of 11 papers represents a wide variety of topics and gives an overview of the diversity of themes related to saline lakes research.

Very often-saline lakes, especially with high concentrations of dissolved ions, are used for salts and minerals extraction (Last, 2002). Some of these minerals are highly valuable (e.g., lithium). To understand and predict the content of valuable minerals in salt lakes, geological and geochemical studies are required. Song et al. (2023) present study on geological and chemical processes in saline lakes. They measured Li-B concentrations and H-O-Sr-B isotopic compositions of different waters (river, spring, and brine) from the Qarhan Salt Lake (QSL) in western China, combined with the reported K-Sr contents and multiple isotopes of waters to discuss the recharge, source of K-Sr-Li-B and their spatial distributions, by analogy with other evaporite basins in the world. The results show that the K-Li-B-Sr elemental concentrations of brines and their spatial distribution in the QSL are diverse and controlled by Ca-Cl springs in the northern QSL and by thermal springs in the Kunlun Mountains. The authors demonstrated that the formation and evolution of Ca-Cl and thermal springs fundamentally constrain the recharge processes of K-Sr and Li-B elements in the terminal salt lakes of the Qaidam Basin (QB). The study provides a reference for resource exploration in deep formation waters in the evaporite basins.

The majority of inland saline lakes are terminal lakes located in closed (endorheic) basins. The water level and salinity in such lakes are highly vulnerable to the balance of water inflows and surface water evaporation. Cheng et al. (2023) selected three lakes in the northern QB to investigate lake water level fluctuations on different time scales based on extensive in-situ monitoring and satellite observations. They revealed that rapid lake level fluctuations are controlled by different factors: glacier and snow melting with increasing temperature for Sugan Lake and increasing precipitation for Xiao Qaidam and Toson Lakes. This study provided an important scientific basis for assessing the hydrological process and hydrological risk precaution and protection of salt lake resources along with rapid lake expansions in the arid area.

Another study related to water level fluctuations in saline lakes was conducted by Liu et al. (2023). They used Landsat remote sensing and meteorological data to monitor dynamic hydrological changes in Zabuye Salt Lake and Lunggar Glaciers to identify factors governing lake changes and to estimate the potential damage to grasslands and salt pans. Zabuye Salt Lake in Xizang is the only saline lake in the world with natural crystalline lithium carbonate and is an important lithium production base in China; therefore, any changes in this lake are concerning. The authors demonstrated that Zabuye Salt Lake expanded at a rate of 5.28 km²/a. This expansion was closely related to the large-scale melting of a glacier caused by rising temperatures. It is predicted that every meter of water increase in the lake will submerge 7.84 km² of grassland and 2.7 km² of salt pans around the lake.

Another digital technology, the power of geospatial technology, was used to characterize the saline soil and halophytes of the largest inland saline wetland of India (Rajashree et al., 2023). Illegal saltpan encroachment is causing Sambhar, India's largest saline lake, to shrink by 4.23% every decade. The study demonstrated the improvement in soil quality parameters that have occurred over the 2020–2022 years. However, the study demonstrated that this aspect (the halophyte diversity and sail properties) at Lake Sambhar was not studied before. Therefore, there is no reference data to compare the results of the current study with historical records. Considering the shrinkage tendency, if immediate conservation measures are not taken, the halophytes may be completely lost before they can be identified.

Among the most valuable and exploited resources related to saline lakes are cysts of brine shrimp Artemia that are used in aquaculture. Therefore, it is unsurprising that studies on Artemia's physiology and ecology receive much attention. Sui et al. (2023) evaluated the protective effect of Halomonas-ploy-β-hydroxybutyrate on Artemia responded to prolonged summer elevated temperatures against Vibrio. The study demonstrated the beneficial effect of Halomonas-ploy-β-hydroxybutyrate (PHB) in Artemia culture, which supports the use of Halomonas-PHB in the production of bio-secured live feed Artemia. Conover et al. (2023) studied the viability and hatchability of brine shrimp Artemia franciscana cysts after passing through the digestive system of eared grebes Podiceps nigricollis. The study aimed to understand the impact of millions of migrating birds on the Artemia population in the Great Salt Lake. Results demonstrate that eared grebes nutritionally benefit from eating cysts and that they may be an important food source for grebes in late fall. At the same time, enough cysts survive their passage through the digestive system, so grebes can vector hatchable cysts to other waterbodies.

Among the most valuable and exploited resources related to saline lakes are cysts of brine shrimp Artemia that are used in aquaculture. Therefore, it is unsurprising that studies on Artemia's physiology and ecology receive much attention. Sui et al. (2023) evaluated the protective effect of Halomonas-ploy-β-hydroxybutyrate on Artemia responded to prolonged summer elevated temperatures against Vibrio. The study demonstrated the beneficial effect of Halomonas-ploy-β-hydroxybutyrate (PHB) in Artemia culture, which supports the use of Halomonas-PHB in the production of bio-secured live feed Artemia. Conover et al. (2023) studied the viability and hatchability of brine shrimp Artemia franciscana cysts after passing through the digestive system of eared grebes Podiceps nigricollis. The study aimed to understand the impact of millions of migrating birds on the Artemia population in the Great Salt Lake. Results demonstrate that eared grebes nutritionally benefit from eating cysts and that they may be an important food source for grebes in late fall. At the same time, enough cysts survive their passage through the digestive system, so grebes can vector hatchable cysts to other waterbodies.

Saline lakes may be the source of not only minerals or Artemia. Yang et al. (2023) conducted a pilot survey on antimicrobial activity and diversity of soil-derived actinobacteria from different depths in Gudzhirganskoe saline lake in Eastern Siberia. They tested 635 actinobacterial strains affiliated with 21 genera in 12 families of 7 orders and selected 77 strains to evaluate their antimicrobial activities. Streptomyces sp. S6b3-1 was highlighted due to its strong inhibitory activities against Gram-positive bacteria and underlying antibacterial mechanism. This study preliminarily explored the actinobacterial diversity of soil samples collected in the highly alkaline and saline lake Gudzhirganskoe by culture-dependent approach and their capacity to produce antibiotics for the first time, which revealed that it deserves to make more efforts to discover new actinobacterial species and potential new antibiotics from saline lakes.

Artemia, an iconic representative of zooplankton, is abundant in saline lakes above the salinity threshold of ca. 50–100 g/L, which is highly variable and depends on species and local conditions (Shadrin et al. 2019). At lower salinities, the species composition of zooplankton can be quite variable. Barkhatov et al. (2023) analyzed the response of zooplankton abundance in saline meromictic Lake Shira (Siberia, Russia) to a change in circulation regime. The authors used the long-term data (1996–2021) on the summer abundances of the dominant zooplankton species in saline Lake Shira to analyze the response of zooplankton to air temperature and a change in the circulation regime of the lake. They found that all studied groups of zooplankton responded to prolonged summer elevated temperatures by increasing their abundance. In addition, the breakdown of the meromixis (the stable stratification of the water column) of Lake Shira promoted the increase in the zooplankton abundance. That increase coincided with similar responses of other components of the lake's mixolimnion ecosystem. This study highlights the importance of long-term studies and emphasizes that water level and salinity are important determinants of the water column stratification

Even though the biodiversity in saline lakes is often considered lower than in freshwater lakes, it is still highly under investigation. Specifically, it is relevant for the invertebrates that are often considered the least studied species in lakes and other aquatic habitats (Gozlan et al., 2019). Modern methods can help reveal this hidden diversity of saline lakes, e.g., environmental DNA metabarcoding. In their paper, Campbell et al. (2023) demonstrated the potential of eDNA coupled with conventional approaches by targeting five hypersaline lakes at Rottnest Island (Wadjemup) in Western Australia. The combination of metabarcoding with the morphology-based taxonomic analysis described 16 taxa belonging to the orders Anostraca, Diptera, Isopoda, and Coleoptera. DNA-based diversity assessment revealed more taxa at higher taxonomic resolution than the morphology-based taxonomic analysis. However, certain taxa (i.e., Ephydridae, Stratyiomidae, Ceratopogonidae) were only identified via net surveying. These results indicate that great potential resides in combining conventional netbased surveys with novel eDNA approaches in saline and hypersaline lakes.

In recent years, salinity has received much attention as a threat to the ability of freshwater ecosystems to provide ecosystem services. Freshwater salinization has become an issue in many countries (Cunillera-Montcusí et al., 2022), which makes studies on saline lakes an important reference benchmark required to understand the response of the freshwater ecosystem to salinity effects. Zadereev et al. (2023) studied the grazing rate and feeding selectivity of small and large-bodied cladocerans in waters from lakes with different salinity and phytoplankton structure. The study aimed to evaluate the ability of two cladocera species (Moina macrocopa and Daphnia magna) to control phytoplankton abundance by grazing under the effect of salinity. Grazing experiments demonstrated that the abundance of phytoplankton mostly controlled the grazing rate. The grazing rate was reduced at salinity ca. above 3 g/L of NaCl. The detrimental effect of elevated salinity on grazing rate supports growing concern about freshwater salinization negatively affecting water quality, particularly reducing top-down grazing control of phytoplankton.

Communication of complex scientific concepts to a wider audience has become an urgent issue in the modern world. The emerging field of science communication combines various approaches to educate and engage the public in the complex science realm to promote evidence-based policy and, specifically, in nature protection (Bickford et al., 2012). De Leon et al. (2023) present the data collected and lessons learned from using Winogradsky Columns in public spaces for teaching about an important saline lake. Authors worked with museums in Utah to create Winogradsky Columns that would highlight aesthetic properties of the Great Salt Lake ecosystem, which has a salinity gradient from the freshwater wetlands to salt saturation.

The multidisciplinary nature of the International Society for Salt Lake Research and studies on saline lakes is a prerequisite for the linkage between science and society. Conservation and management of saline lakes require the interface between science and policy. Non-governmental organizations can be such an interface. Spain, as a country that hosted 14^th International Conference on Salt Lake Research has a strong tradition of incorporating science into policy and public awareness. Specifically, saline lakes, among one important ecosystem types, are protected and conserved at various levels due to the activities of numerous NGOs. The roundtable with several NGOs was organized during the conference to discuss what we can learn from NGOs in the saline lake and salinas conservation.

The round table highlighted the number of weaknesses and needs of NGOs: lack of connection between stakeholders; vulnerability due to their dependence on volunteers; lack of support from the government; short-term effect of public dissemination actions; perceived distance towards the public, not seen as potential partners. On the other hand, there are some strengths and good practices: create integrated conservation and restoration activities; codecide in natural protected area management; involve stakeholders in citizen science projects; recover traditional land management practices; act as hinges between society-science policies, support the scientific community and cooperate in scientific research projects.

Participants of the round table discussed how NGOs could contribute to bringing the conservation of saline ecosystems to the next level. They highlighted that one possibility is to create a platform or network where NGOs working in saline environments can meet and exchange good practices, case studies, and knowledge in general. The ISSLR may act as a supporting entity to facilitate a space (physical or virtual) to meet and consult the scientific soundness of their work, generate opportunities for cooperation and dissemination, and, in general, cross-fertilize the strengths of both parties.

The next conference of the ISSLR will be organized in 2024 in Turkey (http://isslr.org/conferences/2024-antalya-turkey/). Traditionally, it will gather scientists from various fields of study and practitioners that will continue the multidisciplinary discussions. We thank the editors of the Journal of Oceanology and Limnology for giving us the opportunity to publish this special issue; we also thank all reviewers that have thoroughly reviewed submitted manuscripts. We hope that this collection of papers will be of interest to a broad scientific audience and will attract attention to studies of saline lakes and related ecosystems all over the world.