PubMed · 13549205
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1958-06-14. CLEAN rivers and lakes.. https://doi.org/10.1001/jama.1958.02990240064011
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Saline lakes are hypersensitive to changes in their water balance and therefore show amplified responses to climatic and land-use changes in their catchment. Despite often dramatic ecological impacts, saline lakes rank low on policy agendas as they are assumed to support few ecosystem services and low levels of biodiversity. Here, we challenge this view and evaluate ecosystem services and threatened species in 85 saline lakes distributed across the globe. We show that saline lakes support, additionally to threatened aquatic biota, a diverse range of red-listed terrestrial species that contribute together with a large beta diversity to their conservation value. Further, our results highlight that saline lakes provide a number of culturally and economically important ecosystem services but several of them are 'hidden' and difficult to quantify. We conclude our analysis with best-practice recommendations for sustainable management of saline lakes. Their local adaptation and implementation will be key for safeguarding biodiversity and ecosystem services of these valuable and highly sensitive ecosystems.
We isolated a novel halophilic archaeon, strain DSL9, representing the proposed new species Haloliberatus hailidukes gen. nov., sp. nov., from Dishui Lake, China. Unlike most obligate halophiles, DSL9 survives in low salinity, even distilled water, without lysis. Genomic analysis revealed dual salinity adaptation strategies: salt-in and compatible solutes, including a complete trehalose biosynthesis pathway. The strain harbors multiple plasmids, notably a 111,311 bp large plasmid (pHdsl9-3) encoding replication (Orc1/Cdc6, SSB), transcription (TFIIB), transmission (T4SS cluster, ArdC-like protein), and recombination (XerA) modules. pHdsl9-3 provides auxiliary functions such as defense, genome diversification, ion detoxification, and suggests active horizontal gene transfer. Similar elements are widespread in Halobacteriales, highlighting their role in haloarchaeal genetic diversity and plasticity. The encoded XerA hinted at a function beyond DNA dimer resolution, suggesting it may have been adapted by other archaeal mobile genetic elements. These findings underscore the need to investigate plasmid-driven evolution and environmental adaptation mechanisms in haloarchaea.IMPORTANCEThis study reports the isolation and characterization of DSL9, a novel halophilic archaeon from a freshwater lake. Remarkably, DSL9 defies the typical obligate halophilic lifestyle by surviving in low-salinity environments, including distilled water, without cell lysis. A key discovery is the identification of a 111,311 bp large plasmid harboring essential modules for replication, transcription, transmission, and integration. Widespread distribution of similar elements across Halobacteriales suggests their crucial role in haloarchaeal genetic diversity and plasticity, warranting further study of plasmid-mediated evolution and adaptation strategies.
Crawford Lake has an exceptional stratigraphic record that began recording biannual (varved) sedimentation in the lake basin ~750 years ago, preserving evidence of shifting cultural zones and agricultural practices, from Late Woodland Period Indigenous agriculturalists to the impacts of industrialization during the late 19th century. It was selected as the candidate site for the proposed 'Anthropocene' epoch in 2023-a proposal ultimately rejected in 2024-but the lake's significance extends beyond a formal stratigraphic boundary. Its sediments preserve a long record of human-ecosystem entanglement that captures the cumulative, reverberating nature of local human impacts and global change. While many proxies have been studied at the site, the lake's sedimentary ancient DNA (sedaDNA) record has yet to be investigated. Here, we report on sedaDNA preserved at Crawford Lake over the last ~1300 years. Sedentism and agriculture clearly impacted the entire lake ecosystem, with corresponding shifts observable in the sedaDNA of plants, animals, algae, fungi and bacteria. Canada goose (Branta canadensis) roosting on the lake-likely drawn by foraging opportunities in fields cleared for Three/Four Sisters agriculture and sedentism-contributed to repeated eutrophications and algal blooms that permanently shifted the lake's ecological structure. Subsequent impacts during the Euro-Canadian zone furthered anthropogenic succession, although local impacts have been minimal since closure of the sawmill in 1900 ce, allowing for sensitivity to global change. Beyond the molecular ecological history of the lake, we also evaluate the effectiveness of an Arctic/Subarctic bait-set for palaeoecological reconstructions of the Eastern Woodlands, and the preservation of lake sedaDNA.