Oxygen, Carbon and Phosphorus Flux from Lake Sediments: Regulation Through Epipelic Algae and Bacteria

将研究湖泊沉积物表面的藻类和细菌群落，即藻类和细菌群落，如何控制水-沉积物界面的氧、碳和磷的通量。这项研究围绕四个方面展开：1)阐明沉积物向上覆水中磷的昼夜波动的产生机制；2)确定在沉积物-水界面存在季节性变化的条件下，藻类异养和对亚营养条件的耐受性在维持藻类群落中的重要性；3)确定和量化沉积物-水界面上的生物和物理化学因素在控制湖水氧动力学中的作用；以及4)确定围生植物群落藻类和细菌的各种营养来源。这项研究将在两个地点进行：密歇根州的一个碱性湖劳伦斯湖；以及缅因州奥诺附近的一个酸性湖。最先进的系统将被用于分离和操纵附生植物，允许改变光照水平和生长附生植物的“孔隙水”溶液的化学成分。将使用计算机辅助微电极数据采集系统对沉积物和水柱之间边界层的化学条件进行极其详细的测量。Klug博士的研究团队率先在湖泊生物地球化学研究中使用了这一系统。这项研究的意义在于它侧重于湖泊磷的动态变化。磷已被确定为导致许多湖泊和河流富营养化的营养物质。了解控制这些水体中磷动态的因素对它们的管理显然很重要。Klug博士是湖泊生物地球化学研究的世界领先者。这项研究的制度支持是突出的。生态系统研究计划建议授予这笔赠款。

The ways in which the community of algae and bacteria, the periphyton community, at the sediment surface in lakes controls the fluxes of oxygen, carbon and phosphorus at the water-sediment interface will be studied. The research is organized around four tasks: 1) elucidation of the mechanisms involved in producing the day-night fluctuations of phosphorus afflux from the sediments to the overlying water; 2) determination of the importance of algal heterotrophy and tolerance of suboxic conditions in the maintenance of the algal community under the seasonally changing conditions present at the sediment-water interface; 3) identification and quantification of the roles of the biological and physiochemical factors at the sediment-water interface that are involved in the control of oxygen dynamics of lake hypolimnia; and 4) determination of the various sources of nutrients for the algae and bacteria of the periphyton community. The research will be conducted at two sites: an alkaline lake, Lawrence Lake, in Michigan; and an acidic lake in the vicinity of Orno, Maine. State-of-the-art systems will be used for the isolation and manipulation of periphyton that permits variations in light levels and the chemical composition of the "porewater" solutions in which the periphyton is grown. Extremely detailed measurements of chemical conditions at the boundary layer between sediment and the water column will be made with a computer-aided microelectrode data acquisition system. Dr. Klug's research team has pioneered in the use of this system in studies of lake biogeochemistry. The significance of this research is its focus on phosphorus dynamics of lakes. Phosphorus has been identified as the nutrient responsible for the euthrphication of many lakes and rivers. Understanding factors that control phosphorus dynamics in these water bodies is clearly important to their management. Dr. Klug is a world leader in the study of lake biogeochemistry. The institutional support for this research is outstanding. The Ecosystem Studies Program recommends award of this grant.