Desiccation of ecosystem-critical microbialites in the shrinking Great Salt Lake, Utah (USA)

作者：Carie M. Frantz, Cecilia Gibby, Rebekah Nilson, Cole J. Stern, Maggie Nguyen, Cody Ellsworth, Hank Dolan, Alvin Sihapanya, Jake Aeschlimann, Bonnie K. Baxter · 发表于：PLOS Water · 年份：2023 · DOI：10.1371/journal.pwat.0000100 · 被引用次数：4 · 研究领域：Microbial Community Ecology and Physiology、Geology and Paleoclimatology Research、Marine and coastal ecosystems

Great Salt Lake hosts an ecosystem that is critical to migratory birds and international aquaculture, yet it is currently threatened by falling lake elevation and high lakewater salinity resulting from water diversions in the upstream watershed and the enduring megadrought in the western United States. Microbialite reefs underpin the ecosystem, hosting a surface microbial community that is estimated to contribute 30% of the lake’s primary productivity. We monitored exposure, desiccation, and bleaching over time in an area of microbialite reef. During this period, lake elevation fell by 1.8 m, and salinity increased from 11.0% to 19.5% in open-water portions of the outer reef, reaching halite saturation in hydrologically closed regions. When exposed, microbialite bleaching was rapid. Bleached microbialites are not necessarily dead, however, with communities and chlorophyll persisting beneath microbialite surfaces for several months of exposure and desiccation. However, superficial losses in the mat community resulted in enhanced microbialite weathering. In microbialite recovery experiments with bleached microbialite pieces, partial community recovery was rapid at salinities ≤ 17%. 16S and 18S rRNA gene sequencing indicated that recovery was driven by initial seeding from lakewater. At higher salinity levels, eventual accumulation of chlorophyll may reflect accumulation and preservation of lake material in halite crusts vs. true recovery. Our results indicate that increased wat...