Metabarcoding under Brine: Microbial Ecology of Five Hypersaline Lakes at Rottnest Island (WA, Australia)

Hypersaline ecosystems—aquatic environments where concentration of salt exceeds 35 g L−1—host microbial communities that are highly specialised to cope with these extreme conditions. However, our knowledge on the taxonomic diversity and functional metabolisms characterising microbial communities in the water columns of hypersaline ecosystems is still limited, and this may compromise the future preservation of these unique environments. DNA metabarcoding provides a reliable and affordable tool to investigate environmental dynamics of aquatic ecosystems, and its use in brine can be highly informative. Here, we make use of bacterial 16S metabarcoding techniques combined with hydrochemical analyses to investigate the microbial patterns (diversity and functions) from five hypersaline lakes located at Rottnest Island (WA). Our results indicate lake-driven microbial aquatic assemblages that are characterised by taxonomically and functionally moderately to extremely halophilic groups, with TDS (total dissolved solids) and alkalinity amongst the most influential parameters driving the community patterns. Overall, our findings suggest that DNA metabarcoding allows rapid but reliable ecological assessment of the hypersaline aquatic microbial communities at Rottnest Island. Further studies involving different hypersaline lakes across multiple seasons will help elucidate the full extent of the potential of this tool in brine.

Influence of grazing on populations of the specialist grasshopper Mioscirtus wagneri inhabiting hypersaline habitats in La Mancha Region, Central Spain

Grazing is an influential land use that has introduced profound changes in worldwide landscapes, ecosystems and their species. In this paper, we analysed the influence of grazing on the presence and abundance of the endangered Mioscirtuswagneri, a monophagous grasshopper inhabiting inland hypersaline ecosystems in Spain and showing a marked spatial and genetic fragmentation. Using count transects, we analyzed the presence and abundance of this grasshopper in relation to specific vegetation cover and the abundance of goat and sheep droppings, considering this variable as a surrogate of livestock activity and grazing impact. We found that both the presence and abundance of M.wagneri were positively related to the cover of its host plant Suaedavera and negatively associated with the abundance of droppings. We conclude that dropping abundance is a useful parameter to assess livestock impact and evaluate habitat quality and the conservation status of M.wagneri and many other singular species of macroinvertebrates inhabiting inland hypersaline ecosystems. We highly recommend the use of electric shepherd fencing around all sensitive and protected areas where inland hypersaline ecosystems are present in order to deter livestock. We also suggest intensive educational campaigns for farmers and shepherds, revealing the ecological importance of these singular and unique habitats for rare and exclusive species like M.wagneri and many other coexisting plants and invertebrates.