Salt to conserve: a review on the ecology and preservation of hypersaline ecosystems

Mattia Saccò*, Nicole E. White, Chris Harrod, Gonzalo Salazar, Pablo Aguilar, Carolina F. Cubillos, Karina Meredith, Bonnie K. Baxter, Aharon Oren, Elena Anufriieva, Nickolai Shadrin, Yeri Marambio-Alfaro, Víctor Bravo-Naranjo, Morten E. Allentoft

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

When it comes to the investigation of key ecosystems in the world, we often omit salt from the ecological recipe. In fact, despite occupying almost half of the volume of inland waters and providing crucial services to humanity and nature, inland saline ecosystems are often overlooked in discussions regarding the preservation of global aquatic resources of our planet. As a result, our knowledge of the biological and geochemical dynamics shaping these environments remains incomplete and we are hesitant in framing effective protective strategies against the increasing natural and anthropogenic threats faced by such habitats. Hypersaline lakes, water bodies where the concentration of salt exceeds 35 g/l, occur mainly in arid and semiarid areas resulting from hydrological imbalances triggering the accumulation of salts over time. Often considered the ‘exotic siblings’ within the family of inland waters, these ecosystems host some of the most extremophile communities worldwide and provide essential habitats for waterbirds and many other organisms in already water-stressed regions. These systems are often highlighted as natural laboratories, ideal for addressing central ecological questions due to their relatively low complexity and simple food web structures. However, recent studies on the biogeochemical mechanisms framing hypersaline communities have challenged this archetype, arguing that newly discovered highly diverse communities are characterised by specific trophic interactions shaped by high levels of specialisation. The main goal of this review is to explore our current understanding of the ecological dynamics of hypersaline ecosystems by addressing four main research questions: (i) why are hypersaline lakes unique from a biological and geochemical perspective; (ii) which biota inhabit these ecosystems and how have they adapted to the high salt conditions; (iii) how do we protect biodiversity from increasing natural and anthropogenic threats; and (iv) which scientific tools will help us preserve hypersaline ecosystems in the future? First, we focus on the ecological characterisation of hypersaline ecosystems, illustrate hydrogeochemical dynamics regulating such environments, and outline key ecoregions supporting hypersaline systems across the globe. Second, we depict the diversity and functional aspects of key taxa found in hypersaline lakes, from microorganisms to plants, invertebrates, waterbirds and upper trophic levels. Next, we describe ecosystem services and discuss possible conservation guidelines. Finally, we outline how cutting-edge technologies can provide new insights into the study of hypersaline ecology. Overall, this review sheds further light onto these understudied ecosystems, largely unrecognised as important sources of unique biological and functional diversity. We provide perspectives for key future research avenues, and advocate that the conservation of hypersaline lakes should not be taken with ‘a grain of salt’.

Original languageAmerican English
Pages (from-to)2828-2850
Number of pages23
JournalBiological Reviews
Volume96
Issue number6
DOIs
StatePublished - Dec 2021

Bibliographical note

Funding Information:
M.S., N.E.W. and M.E.A. are supported by the BHP Social Investment Fund, eDNA for Global Biodiversity (eDGES) programme. E.A. and N.S. worked for this study in the framework of the state assignments of the A.O. Kovalevsky Institute of Biology of the Southern Seas of RAS (Russia) (? 121041500203-3). V.B.-N. thanks the support of the DIDULS-2020 program: Research on Sustainability and Natural Systems of central Chile of the Universidad de La Serena. C.H. is supported by Nucleo Milenio INVASAL funded by ANID ? Millennium Science Initiative ? NCN16_034.

Funding Information:
M.S., N.E.W. and M.E.A. are supported by the BHP Social Investment Fund, eDNA for Global Biodiversity (eDGES) programme. E.A. and N.S. worked for this study in the framework of the state assignments of the A.O. Kovalevsky Institute of Biology of the Southern Seas of RAS (Russia) (№ 121041500203‐3). V.B.‐N. thanks the support of the DIDULS‐2020 program: Research on Sustainability and Natural Systems of central Chile of the Universidad de La Serena. C.H. is supported by Nucleo Milenio INVASAL funded by ANID – Millennium Science Initiative – NCN16_034.

Publisher Copyright:
© 2021 Cambridge Philosophical Society.

Keywords

  • conservation
  • ecosystem services
  • energy flows
  • extremophile
  • food webs
  • functional ecology
  • nutrient flows
  • wetlands

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