Santa Barbara Coastal LTER. marine metagenome

The Santa Barbara Channel (SBC) is located on an extremely narrow region of the continental shelf, being only a few kilometers wide in many areas. This allows greater potential for cross shelf processes that affect supply and export of key resources to and from the near shore rocky reef environment. A monthly cross shelf time series program was initiated in January 2008 - April 2009 from the shallow rocky reef environment into the Santa Barbara Channel to examine the onshore to offshore gradients of inorganic and organic nutrients, as well as microbial processes and community structure. The main goals of this study were to (1) to assess the evolution and persistence of temporal and spatial gradients in biogeochemical parameters and how that variability coincided with bacterioplankton dynamics (2) assess the bioavailability of the accumulated DOM via laboratory seawater culture approaches, and (3) investigate the significance of bacterioplankton production, community structure and its associated demand for organic carbon in this near shore environment. These data reveal significant gradients in dissolved organic matter and microbial activity and suggest that at times the near shore rocky reef environment could be highly isolated from offshore waters. If the accumulation of a pool of organic matter resists microbial degradation, then when connectivity between the near shore and offshore does occur a significant flux of energy and associated nutrients could be potentially exported away from this near shore system and remineralized off shore. We hypothesize that the physical and chemical gradients that develop along these horizontal gradients play an important role in structuring the microbial community. In May and September 2008 samples were collected from 5 m depth along the onshore - offshore transect for MIRADA's project for obtaining deep pyrosequencing of the prokaryotic and eukaryotic microbial community. The time points were chosen to represent the period of spring bloom activity and the autumn stratified period. These data combined with the DNA fingerprint data and the biogeochemical variables of nutrients, dissolved and particulate organic matter, primary and bacterial production and biomass will elucidate whether patterns of biogeochemistry will reveal emerging patterns of microbial community structure.

圣巴巴拉海峡（Santa Barbara Channel, SBC）地处大陆架极端狭窄的区域，多数区域宽度仅数公里，这为跨陆架过程提供了更大的发生潜力——这类过程会影响近岸岩礁生境关键资源的补给与输出。2008年1月至2009年4月，研究团队启动了一项月度跨陆架时间序列项目，从浅海岩礁生境延伸至圣巴巴拉海峡，旨在探究无机与有机营养盐的岸-海梯度分布，以及微生物过程与群落结构特征。本研究的核心目标有三：（1）评估生物地球化学参数的时空梯度演化与持续性，及其与浮游细菌动态的耦合关系；（2）通过实验室海水培养法，评估累积溶解有机物（dissolved organic matter, DOM）的生物可利用性；（3）探究近岸生境中浮游细菌生产、群落结构及其伴随的有机碳需求的生态学意义。本数据集揭示了溶解有机物与微生物活性的显著梯度，并表明近岸岩礁生境有时会与外海水体高度隔离。若某一有机碳库的累积过程能抵御微生物降解，那么当近岸与外海的连通性恢复时，大量能量与相关营养盐可能会从该近岸系统向外输出，并在远海发生再矿化。我们提出假说：沿这些水平梯度形成的物理与化学梯度，在微生物群落结构构建中发挥着重要作用。2008年5月与9月，研究团队沿岸-海断面在5米深度处采集了样本，用于MIRADA项目的原核与真核微生物群落深度焦磷酸测序（pyrosequencing）。选取这两个时间点是为了分别代表春季水华活动期与秋季层化期。将本数据集与DNA指纹图谱数据、营养盐、溶解态与颗粒态有机物、初级生产与细菌生产及生物量等生物地球化学变量相结合，将有助于阐明生物地球化学模式是否能揭示微生物群落结构的新兴分布格局。