LTER - Georgia Land/Ocean Margin Ecosystem

将在萨佩洛岛附近的格鲁吉亚中部海岸建立一个长期生态研究基地。这是一个屏障岛和沼泽复合体，Altamaha河是美国东海岸最大和最不发达的河流之一，是淡水的主要来源。将调查由水-地表水和地下水-输送到沿海地区所介导的当地和遥远的高地地区之间的联系。将研究由河流驱动的环境因素变化（主要是盐度，因为我们可以高频率地测量盐度）与生态系统过程和结构之间的关系。这将通过比较一个或两个泻湖河口/沼泽复合体，阻尼和衰减的河流信号从阿尔塔马哈河分开河口/沼泽复合体。这种空间梯度类似于流域发展所带来的河流影响的时间趋势。将实施一个监测系统，记录物理和生物变量。这些变量的时间趋势和空间分布及其方差结构将被用来解决问题的因素控制分布，营养结构，多样性，和bioeochemical.A现有的基于GIS的水文模型将被修改，以纳入河流水的变化，土地利用模式的变化，可以预期的流域发展。这一模式将与生态系统模式相联系，并将作为一种启发和管理工具。 沿海开发的另一个后果是，随着河流流量的减少，地下水流量增加并得到营养。地下水排放的影响，从地表含水层在相对原始的（萨佩洛岛）将进行比较，对更多的城市化（大陆）的网站，以评估相对重要性的淡水与营养物质的生产力，结构和生物量周转率在沼泽地的影响，地下水。将研究海洋过程（潮汐、风暴潮）对表层含水层淡水/盐界面混合的影响。 进一步的物理研究将把盐沼-潮沟通道复合体的形态与潮流分布和交换联系起来。这些研究结果将纳入一个物理模型，该模型将与现有的生态系统模型相结合，这一陆地/海洋边缘生态系统位于两个生态系统之间的界面，在这两个生态系统中，控制有机物降解的分解者截然不同。真菌分解者在陆地生态系统中占主导地位，而细菌分解者则在海洋生态系统中占主导地位。这两个群体在以盐沼为主的生态系统中都很重要。具体的研究将检查，在单个细胞和菌丝的水平上，在分解立死米草和其他沼泽植物的财团中的细菌和真菌的关系，并检查如何，或者如果，这种变化沿着盐度梯度。

A Long Term Ecological Research site will be established on the central Georgia coast in the vicinity of Sapelo Island. This is a barrier island and marsh complex with the Altamaha River, one of the largest and least developed rivers on the east coast of the US, as the primary source of fresh water. The linkages between local and distant upland areas mediated by water - surface water and ground water - delivery to the coastal zone will be investigated. The relationship between variability in environmental factors driven by river flow, primarily salinity because we can measure it at high frequency, and ecosystem processes and structure will be examined. This will accomplished by comparing estuary/marsh complexes separated from the Altamaha River by one or two lagoonal estuary/marsh complexes that damp and attenuate the river signal. This spatial gradient is analogous to the temporal trend in riverine influence expected as a result of development in the watershed. A monitoring system will be implemented that documents physical and biological variables. The time trends and spatial distributions of these variables and of their variance structure will be used to address questions about the factors controlling distributions, trophic structure, diversity, and biogeochemistry.An existing GIS-based hydrologic model will be modified to incorporate changes in river water resulting from changes in land use patterns that can be expected as the watershed develops. This model will be linked to ecosystem models and will serve as a heuristic and management tool. Another consequence of coastal development is that as river flow decreases, groundwater flow increases and becomes nutrified. The effects of ground water discharge from the surficial aquifer in relatively pristine (Sapelo Island) will be compared against more urbanized (mainland) sites to assess the relative importance of fresh water versus nutrients to productivity, structure and biomass turnover rate in marshes influenced by groundwater. The effect of marine processes (tides, storm surge) on mixing across the fresh/salt interface in the surficial aquifer will be investigated. Additional physical studies will relate the morphology of salt marsh - tidal creek channel complexes to tidal current distributions and exchange. These findings will be incorporated into a physical model that will be coupled to an existing ecosystem model.This land/ocean margin ecosystem lies at the interface between two ecosystems in which distinctly different groups of decomposers control organic matter degradation. Fungal decomposers largely dominate the terrestrial ecosystem, while bacterial decomposers dominate the marine ecosystem. Both groups are important in salt marsh-dominated ecosystems. Specific studies will examine, at the level of individual cells and hyphae, the relationship bacteria and fungi in the consortia that decompose standing dead Spartina and other marsh plants and, examine how, or if, this changes along the salinity gradient.