Persistence and Fate of Domoic Acid in the Santa Barbara Basin

各种藻类的有毒繁殖（有害藻华- HABs）在世界各地都有记录。最终影响到大面积的贝类、鱼类、海洋哺乳动物和鸟类。假硅藻属（一组产生神经毒素软骨藻酸（DA）的海洋硅藻）中的几个物种已被确定为加利福尼亚海岸藻类组合的共同成员。有害藻华研究的关键问题不仅包括是什么导致有毒的伪硝氏菌繁殖，还包括它死亡后会发生什么。从沿海富营养化到增加的上升流，再到沉积物中种子种群的再悬浮，这些因素都是假设的，但仍然是谜，主要是由于缺乏综合数据。产生伪nitzschia花的DA的命运仍然更加难以捉摸，然而越来越多的证据表明，在沿海和近海的底栖动物和底栖生物中都有大量的DA浓度。在这个项目中，南卡罗来纳大学哥伦比亚分校的一个研究小组将基于有趣和令人兴奋的初步数据，这些数据表明下沉颗粒是从地表水到沉积物的主要垂直运输机制，在超过500米的深度，DA通量超过50,000 ng DA/m2/d。他们假设，DA会被迅速转移到沉积物中，并且可能在假性尼齐亚花消失后很长一段时间内持续存在，而不是季节性的时间尺度。他们的目标是建立一个以圣巴巴拉盆地（SBB）为重点的区域观测和建模程序，具体包括：1)研究伪尼齐亚藻华、DA毒性以及伪尼齐亚藻和DA向底底生物的垂直运输效率之间的时间关系；2)研究DA与沉积物的结合；3)建立过去十年（可能是上个世纪）的DA毒性历史记录。为了实现这一目标，他们将结合每月对水柱生物地球化学的调查巡航，两个连续系泊的沉积物陷阱（150米和550米），区域表面和核心沉积物记录，卫星图像，并开发一个数值模型，以检查有毒伪尼氏藻华的表面时间和DA向海底的垂直出口。他们期望这项研究将从根本上改变目前对海洋系统中DA毒性持久性的看法，并将为其他有害毒素的类似测量提供基础。拟议的研究利用了加利福尼亚沿海许多正在进行的项目的采样机会，如羽状和华状和圣巴巴拉海岸LTER项目（水柱），南加州大学海洋沉积物实验室（存档和未来沉积物陷阱收集），以及南加州沿海水研究项目2008年活动（表层和下芯沉积物收集）。预计该项目将产生一系列更广泛的影响。除了与有害藻华研究和海洋环境毒理学明显相关外，该项目还将直接资助一名博士后和一名美洲原住民研究生。本科生也将参与拟议的研究，由南卡罗来纳大学提供内部资金支持。所有学生都是首席研究员吗？他的实验室参加了Science Quest，这是一个面向处境危险的中小学生（8 -14岁）的课外非正式科学技术项目。

Toxic blooms of a variety of algal species (harmful algal blooms -- HABs) have been documented throughout the world?s coastal oceans, ultimately impacting shellfish, finfish, marine mammals and birds over large areas. Several species within the genus of Pseudo-nitzschia, a group of marine diatoms that produce the neurotoxin domoic acid (DA), have been identified as common members of algal assemblages along the coast of California. Key questions in HAB research include not only what causes toxic Pseudo-nitzschia spp. to bloom, but what happens to that bloom after its demise. Causative factors ranging from coastal eutrophication to increased upwelling to resuspension of seed populations from sediments have all been hypothesized, but remain enigmatic, mainly due to a paucity of integrative data. The fate of DA producing Pseudo-nitzschia blooms remains even more elusive, and yet there is increasing evidence of substantial DA concentrations in benthopelagic feeders and benthic organisms both along the coast and offshore. In this project, a research team at the University of South Carolina at Columbia will build upon intriguing and exciting preliminary data that suggests that sinking particles are a major vertical transport mechanism of DA from surface waters to sediments, with DA fluxes exceeding 50,000 ng DA/m2/d at depths in excess of 500 m. They hypothesize that DA is rapidly transported to sediments and likely persists on greater than seasonal timescales, well after the demise of a Pseudo-nitzschia bloom. Their goal is to create a regional observation and modeling program focused on the Santa Barbara Basin (SBB) that specifically: 1) Examines the temporal relationship between Pseudo-nitzschia blooms, DA toxicity, and the vertical transport efficiency of Pseudo-nitzschia and DA to the benthos, 2) Investigates the incorporation of DA into the sediments, and 3) establishes a historical record of DA toxicity spanning the past decade, and potentially, the last century. To achieve this goal, they will use a combination of monthly survey cruises of water column biogeochemistry, two continuously moored sediment traps (150 and 550 m), regional surface and down core sediments records, satellite imagery and develop a numerical model that examines the surface timing of toxic Pseudo-nitzschia blooms and the vertical export of DA to the seafloor. They expect that this research will fundamentally change current views on the persistence of DA toxicity in marine systems and that it will provide the groundwork for similar measurements of other harmful toxins. The proposed research leverages sampling opportunities with a number of ongoing programs off coastal California, such as Plumes and Blooms and the Santa Barbara Coastal LTER Project (water column), the Marine Sediments Laboratory at USC (archived and future sediment trap collections), and the Southern California Coastal Water Research Project Bight 2008 campaign (surface and down core sediment collections). The project is expected to have a number of broader impacts. Beside its obvious relevance to HAB research and marine environmental toxicology, the project will directly support a postdoctoral fellow and one Native American graduate student. Undergraduate students will also participate in the proposed research, supported by internal funds contributed by the University of South Carolina. All students in the principal investigator?s laboratory participate in Science Quest, an after school informal science and technology program geared towards at-risk elementary and middle school students (ages 8 -14).