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

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。它们的生产力通常很高，支持更高的营养水平，尤其是鸟类。在加州的莫诺湖，人们对环境的关注主要集中在随着淡水流从流域转移而增加的盐度威胁上。州政府机构现在已经限制了洛杉矶的水权，以提高和维持莫诺湖的表面高度，使其明显高于目前的水平。不同湖泊水位和盐度的生态响应是不确定的。近16年来，Mono湖浮游生物动态以养分有效性的大变化为主。对单个生物的盐度生物分析和模型研究预测，在低盐度和高地表海拔地区，初级和次级生产力更高。然而，最近对沉积物岩心的分析表明，过去170年的盐度变化与沉积物中的有机质积累之间的相关性很小。这项研究将通过关键的湖泊测量来确定盐度变化对预期湖泊水位上升和盐度下降期间的响应，将直接将所得到的浮游生物动态的长期记录与沉积记录进行比较，并包括对150-200年的沉积记录的分析，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21年浮游生物动态记录与沉积物中有机质积累的比较。盐湖正日益受到人类造成的盐度变化的威胁。该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，这项研究将推动在…了解物种多样性对生态系统基本功能的影响。对于大型的、温带的、相对较深的、物种较少的湖泊，没有可比较的记录来与研究充分的、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.