Persistence and Fate of Domoic Acid in the Santa Barbara Basin

世界各地都有记载各种藻类的有毒水华(有害藻华--赤潮)--S说，这些水华最终会影响沿海海洋，最终影响贝类、鳍类、海洋哺乳动物和鸟类的大片区域。伪菱形藻是一组海洋硅藻，能产生神经毒素软骨藻酸(DA)，该属中的几个物种已被鉴定为加州海岸藻类组合的常见成员。HAB研究中的关键问题不仅包括是什么导致了有毒的伪菱形藻。开花，但花朵消亡后会发生什么。从沿海富营养化到上升流增加，再到种子种群从沉积物中重新悬浮，这些原因都被假设了，但仍然是谜，主要是因为缺乏综合数据。多巴胺产生假菱形藻水华的命运仍然更加扑朔迷离，然而，越来越多的证据表明，沿海和近海的海底摄食者和底栖生物中的多巴胺浓度相当高。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建立在耐人寻味和令人兴奋的初步数据的基础上，这些数据表明，下沉颗粒是DA从地表水到沉积物的主要垂直输送机制，在超过500米的深度，DA通量超过50,000 ng DA/m2/d。他们假设DA被迅速输送到沉积物中，并可能持续比季节性时间尺度更长的时间尺度，很好地在假性菱形藻水华消亡之后很久。他们的目标是创建一个以圣巴巴拉盆地(SBB)为重点的地区性观测和模拟计划，具体如下：1)研究拟菱形藻水华、DA毒性和拟菱形藻和DA向底栖生物的垂直输送效率之间的时间关系；2)调查DA在沉积物中的结合情况；3)建立跨越过去十年，甚至上个世纪的DA毒性的历史记录。为实现这一目标，他们将综合利用水柱生物地球化学月度调查巡航、两个连续系泊沉积物捕捉器(150米和550米)、区域表层和下方岩心沉积物记录、卫星图像，并开发一个数值模型，审查有毒假性菱形藻大量繁殖的表面时间和DA垂直出口到海底的情况。他们预计，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奠定基础。拟议的研究利用了加州沿海正在进行的一些项目的采样机会，例如羽流和水华和圣巴巴拉海岸LTER项目(水柱)、南加州大学的海洋沉积物实验室(存档的和未来的沉积物捕集器收集)以及南加州海岸水研究项目Bight 2008活动(表层和向下的核心沉积物收集)。预计该项目将产生一些更广泛的影响。除了与HAB研究和海洋环境毒理学有明显的相关性外，该项目还将直接支持一名博士后研究员和一名美洲原住民研究生。本科生也将参与这项由南卡罗来纳大学捐赠的内部资金支持的拟议研究。首席研究员S实验室的所有学生都参加了科学探索，这是一个课外非正式的科学技术项目，面向高危中小学生(8-14岁)。

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).