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

按体积计算，湖泊占内陆水域的近一半，为干旱地区提供了重要的生态栖息地。它们通常有很高的生产力，这支持了更高的营养水平，特别是鸟类。在加利福尼亚州的莫诺湖，环境问题的重点是随着淡水溪流分水岭外的分水岭改道而对盐度增加的威胁。国家机构现在已经规定洛杉矶的水权必须提高并保持莫诺湖的水面高度明显高于目前的水平。对不同湖泊水位和盐度的生态反应是不确定的。在过去的16年里，莫诺湖S浮游生物的动态以营养盐有效性的巨大变化为主导。对单个生物体的盐度生物分析和模拟研究预测，在盐度较低的地区，伴随着较高的地表海拔，初级和次生生产力较高。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质的积累之间几乎没有相关性。S的研究将通过湖平面上升和盐度下降的预期时期的关键湖相测量来确定盐度变化的响应，将直接将由此产生的浮游生物动态的长期记录与沉积记录进行比较，并包括分析150-200年的沉积记录，其中可以获得湖平面和盐度的估计。21年浮游生物动态记录与沉积物中有机质积累之间的对比将通过同时测量下沉通量而得到加强。咸水湖正日益受到人类造成的盐度变化的威胁。这项拟议的研究不仅解决了莫诺湖盐度变化的影响，而且有助于解释其他湖泊的沉积记录。此外，这项研究将推动了解物种多样性对生态系统基本功能的影响。对于大型、温带、相对较深、物种贫乏的湖泊，没有可比的记录，可以与研究充分、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。

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.