Microcosm Investigations of Carbonate Reef Microbial Biogeochemistry

该项目是一个为期一年的概念验证项目，展示了使用实验室微观实验来研究大气CO2水平升高和碳酸盐溶解度升高对碳酸盐礁微生物群落和生物地球化学的影响。这项研究项目是在夏威夷卡内奥赫湾海洋生物研究所进行的。HIMB是一个长期监测项目的地点，该项目研究海湾河口和珊瑚礁生态系统之间的动态相互作用。在这个示范阶段，pi正在重建珊瑚礁内部沉积物及其异养微生物群落；该系统正在从海水中“喂食”天然颗粒有机物质。目的是复制在自然珊瑚礁系统中观察到的地球化学梯度，并生成关于二氧化碳升高对珊瑚礁水力学、碳酸盐矿物学、孔隙水化学和微生物学影响的初步数据。测量包括水力导电性和沉积物中大块碳酸盐矿物组分的变化。利用电子显微镜、x射线衍射和阴极发光对碳酸盐骨架的结构和矿物学进行了研究。孔隙水分析是测量碳酸盐化学（pH，碱度，Mg2+和Ca2+）和氧化还原指标（溶解O2和NH4+）。沉积物微生物群落沿沉积物氧化还原梯度的变化是通过直接计数和16S rRNA种类来监测的。

Gaidos AbstractThis project is a one-year proof-of-concept project that is demonstrating the use of laboratory microcosm experiments to investigate the impact of elevated atmospheric CO2 levels and higher carbonate solubility on the microbial community and biogeochemistry of carbonate reefs. The research program is being carried out at the Hawaii Institute of Marine Biology in Kaneohe Bay. HIMB is the site of a long-term monitoring project that studies the dynamical interaction between estuarine and reef ecosystems in the bay. For this demonstration phase, the PIs are reconstructing the interior reef sediment and its heterotrophic microbial community; the system is being "fed" natural particulate organic matter from seawater. The objectives are to replicate the geochemical gradients observed in the natural reef system and generate preliminary data on the effect of elevated CO2 on reef hydraulics, carbonate mineralogy, porewater chemistry, and microbiology. Measurements include the hydraulic conductivity and changes in the bulk carbonate mineral fraction of the sediments. The structure and mineralogy of the carbonate framework is being studied using electron microscopy, X-ray diffraction and cathodoluminescence. Porewater analyses is measuring carbonate chemistry (pH, alkalinity, Mg2+ and Ca2+) and redox indicators (dissolved O2 and NH4+). Variation in the sediment microbial community along the sediment redox gradient is being monitored by direct counts and 16S rRNA phylotypes.