Desiccation of ecosystem-critical microbialites in the shrinking Great Salt Lake, Utah (USA)
Desiccation of ecosystem-critical microbialites in the shrinking Great Salt Lake, Utah (USA)
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DOI：
10.1371/journal.pwat.0000100
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发表时间：
2023-09
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影响因子：
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通讯作者：
Carie Frantz;Cecilia Gibby;R. Nilson;Cole J. Stern;Maggie Nguyen;Cody Ellsworth;Hank Dolan;Alvin Sihapanya;Jake Aeschlimann;Bonnie K. Baxter
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作者：
Carie Frantz;Cecilia Gibby;R. Nilson;Cole J. Stern;Maggie Nguyen;Cody Ellsworth;Hank Dolan;Alvin Sihapanya;Jake Aeschlimann;Bonnie K. Baxter
大盐湖拥有一个对候鸟和国际水产养殖至关重要的生态系统，但目前它正受到上游流域水改道和美国西部持续特大干旱造成的湖面海拔下降和湖水盐度高的威胁。微生物岩礁是生态系统的基础，拥有一个表面微生物群落，估计贡献了该湖 30% 的初级生产力。我们监测了微生物岩礁区域随时间的暴露、干燥和漂白情况。在此期间，湖面海拔下降了1.8 m，外礁开放水域盐度从11.0%增加到19.5%，水文封闭区达到石盐饱和状态。当暴露时，微生物岩迅速漂白。然而，漂白的微生物岩并不一定已经死亡，微生物群落和叶绿素在微生物岩表面下持续存在数月的暴露和干燥。然而，垫层群落的表面损失导致微生物岩风化作用增强。在使用漂白微生物岩碎片的微生物岩恢复实验中，在盐度≤ 17% 时部分群落恢复很快。 16S 和 18S rRNA 基因测序表明恢复是由湖水的初始播种驱动的。在较高的盐度水平下，叶绿素的最终积累可能反映了石盐结壳中湖泊物质的积累和保存与真正的恢复。我们的结果表明，应优先考虑增加水输入，以使湖泊恢复到淹没微生物礁并降低盐度水平的高度。如果不迅速采取行动扭转流域的改道，持续的高盐度导致中上层微生物群落成员的丧失可能会阻碍大盐湖生态系统关键微生物岩表面群落的恢复。
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 water input should be prioritized in order to return the lake to an elevation that submerges microbialite reefs and lowers salinity levels. Without quick action to reverse diversions in the watershed, loss of pelagic microbial community members due to sustained high salinity could prevent the recovery of the ecosystem-critical microbialite surface communities in Great Salt Lake.