LTREB: Responses of a Saline Lake to Environmental Change from Seasonal to Decadel Time Scales

LTREB：盐湖对季节到十年时间尺度环境变化的响应

• 批准号: 9508733
• 负责人: John Melack
• 金额: $ 25.07万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9508733&HistoricalAwards=false
• 关键词: LTREB; Responses; Saline; Lake; Environmental

Lakes constitute nearly half of inland waters by volume and provide ecologically important habitats in arid regions. They often have high rates of productivity which support higher trophic levels, especially birds. At Mono Lake, California, environmental concern has focused on the threat to increasing salinity accompanying diversions of freshwater streams out of the watershed. State agencies have now conditioned Los Angeles water rights to raise and maintain the surface elevation of Mono Lake at a level significantly higher than the present. The ecological response to different lake levels and salinities is uncertain. During the past 16 years, Mono Lake s plankton dynamics were dominated by large changes in nutrient availability. Salinity bioassays on individual organisms and modeling studies predict higher primary and secondary productivity at the lower salinities accompanying higher surface elevations. However, recent analysis of sediment cores indicate little correlation between changes in salinity over the past 170 years and organic matter accumulation in the sediments. Thi s research will determine the response to change in salinity through key limnological measurements during the anticipated period of rising lake levels and decreasing salinity,will directly compare the resulting long-term record of plankton dynamics to the sedimentary record, and includes analysis of a 150-200 year sedimentary record for which lake level and salinity estimates are available. The comparison between the 21-yr record of plankton dynamics and organic matter accumulation in the sediments will be enhanced through contemporaneous measurements of sinking fluxes. Saline lakes are increasingly threatened by human-caused changes in salinity. The proposed research not only addresses the impact of changing salinity at Mono Lake, but also contributes to interpreting the sedimentary record of other lakes. Additionally, this research will advance efforts at.understanding the effect of species diversity on basic functioning of ecosystems. There are no comparable records for large, temperate, relatively deep, species poor lakes with which to compare to well-studied, species-rich, temperate lakes. This research will help to fill that void.

湖泊占内陆沃茨的近一半，是干旱地区重要的生态生境。它们通常具有高生产率，支持更高的营养水平，特别是鸟类。在加州的莫诺湖，环境问题集中在随着淡水流流出分水岭而增加的盐度的威胁上。 州政府机构现在已经对洛杉矶的水权进行了调整，以提高并保持莫诺湖的水面高度明显高于目前的水平。不同的湖泊水位和盐度的生态响应是不确定的。在过去的16年里，莫诺湖的浮游生物动态主要是由营养物质的可利用性的巨大变化。对单个生物的盐度生物测定和建模研究预测，在较低的盐度伴随较高的表面海拔较高的初级和次级生产力。然而，最近对沉积物岩心的分析表明，过去170年来盐度的变化与沉积物中有机物的积累之间几乎没有关联。这项研究将在预期的湖平面上升和盐度下降期间通过关键的湖沼学测量确定对盐度变化的反应，将直接比较浮游生物动态的长期记录与沉积记录，并包括分析150-200年的沉积记录，其中湖泊水位和盐度估计是可用的。通过同时测量下沉通量，将加强浮游生物动态和沉积物中有机物积累的21年记录之间的比较。 咸水湖越来越受到人为造成的盐度变化的威胁。这项研究不仅解决了莫诺湖盐度变化的影响，还有助于解释其他湖泊的沉积记录。此外，这项研究还将促进人们了解物种多样性对生态系统基本功能的影响。没有大型、温带、相对较深、物种贫乏的湖泊的可比记录，可与研究充分、物种丰富的温带湖泊进行比较。这项研究将有助于填补这一空白。