Benthic Dinoflagellate Migration (BenDiM): Occurrence and Processes

由于表层水华的可见性，大多数标准的甲藻垂直迁移(DVM)假说的应用考虑了白天的表层目标和夜间的次表层营养目标。然而，地下营养源可能很深，以至于甲藻在12小时的上升过程中无法到达表面。至少有三份文献报告记录了以沉积物为导向的另一种DVM模式的表达，其特征是大陆边界更宽、更缓倾斜的陆架，可以产生高生物量、接近底部的甲藻堆积。目标甲藻生态位，这里称为“底栖甲藻迁移”或“本迪姆”，受到光照和营养梯度的影响，但其独特之处在于，在靠近或位于沉积物-海界面的营养源与支持种群净增加的下部真光带的光照强度之间存在DVM。该项目具体涉及：1)5月至11月在佛罗里达州巴拿马城外60米至20米等高线之间的大陆架上占据本迪姆生态位的不同甲藻物种；2)占据本迪姆生态位的不同甲藻物种的光适应、营养吸收能力和所需的行为模式；以及3)具有代表性的物理水分运动对不同本迪姆甲藻种群形成、运输和命运的影响。这项研究包括：1)在2008年5月至10月和2009年7月至8月的不同月份，进行三次为期7天的远洋/底栖实地考察；2)对能够成功与近底浮游硅藻和小型底栖植物竞争的本迪姆甲藻的光、营养和行为特征进行实验室研究；以及3)物理-生物模拟研究，以规划、整合和扩展现场和实验室结果。巡航方案应用了联合国全球海洋观测系统的标准船舶能力，并配备了各种仪器，包括：1)Acrobat起伏系统，配备有海鸟CTD-O2系统、生物圈PAR、海点叶绿素和CDOM荧光仪、Seapoint浊度计、卫星Isus硝酸盐传感器、Brooke-Ocean激光浮游生物计数器和具有集成GPS和回波探测定位系统和实时图形显示收集数据的通用海洋流量计，2)FlowCAM，3)自主垂直剖面仪。实验室工作应用了一种经过验证的运动分析系统来研究甲藻的行为，并应用了一种发达的中微体能力来研究甲藻的生理、生化和行为。建模工作建立在现有的生物密集型建模方法的基础上，该方法结合了甲藻生理、生化和典型物理场中的行为的参数化。这一智能优势直接适用于“隐形”水华的启动，因为正在形成的本迪姆生物量一般是看不见的，因为它发生在卫星探测的第一个光学深度以下。BenDim还牵涉到对碳出口的改进估计，因为在常规真光带调查和营养关系中可能会遗漏这种生物量，因为这种生物量可能对食草动物有利或有害，这取决于在给定地点和时间主导生态位的甲藻物种。更广泛的影响包括：NCSU和UNW的研究生和本科教育；通过COSEE进行高中教师教育；在国家/国际会议上向同事传递信息；以及通过COSEE协助的DVD向公众传递关于邮轮活动的信息。

Most applications of the standardized dinoflagellate diel vertical migration (DVM) hypothesis consider a surface goal in daylight and a subsurface nutrient goal at night because of the visibility of surface blooms. The sub-surface nutrient source, however, can be so deep that dinoflagellates are unable to reach the surface during a 12 h ascent. At least three literature reports document a sediment-oriented expression of an alternative DVM pattern characteristic of continental boundaries with wider, more gently sloping shelves that can yield high biomass, near-bottom dinoflagellate accumulations. The targeted dinoflagellate niche, here termed ''Benthic Dinoflagellate Migration'' or ''BenDiM'', is influenced by light and nutrient gradients but is unique in that a DVM exists between a nutrient source near or at the sediment-sea interface and a light intensity in the lower euphotic zone that supports a net increase in population size. The project specifically deal with: 1) the different dinoflagellate species that occupy the BenDiM niche on the continental shelf off Panama City, FL between the 60 m and 20 m contours between May and Nov; 2) the light acclimation, the nutrient uptake capabilities, and the behavioral patterns required of different dinoflagellate species that occupy the BenDiM niche; and, 3) the effect of representative physical water motion on the formation, transport and fate of the different BenDiM dinoflagellate species populations. The study includes: 1) a pelagic/benthic field program with three 7-day cruises during different months between May and Oct in 2008 and Jul-Aug 2009; 2) laboratory studies on the light, nutrient, and behavioral characteristics of BenDiM dinoflagellates that allow successful competition with near-bottom pelagic diatoms and the microphytobenthos; and 3) a physical-biological modeling study to plan, integrate and extend the field and laboratory results. The cruise program applies standard UNOLS ship capabilities extended with instrumentation that includes: 1) an Acrobat undulating system instrumented with SeaBird CTD-O2 system, Biospherical PAR, SeaPoint Chlorophyll and CDOM Fluorometers, Seapoint Turbidity, Satlantic ISUS Nitrate Sensor, Brooke-Oceans Laser Optical Plankton Counter, and General Oceanics Flow Meter with integrated GPS and echo sounding location system and a real-time graphical display of the collected data, 2) the FlowCAM, and 3) the autonomous vertical profiler (AVP). The laboratory effort applies a proven motion analysis system for studying dinoflagellate behavior and a well-developed mesocosm capability for studying dinoflagellate physiology, biochemistry, and behavior. The modeling effort builds on an existing, biologically intense modeling approach that incorporates parameterization of dinoflagellate physiology, biochemistry and behavior in a representative physical field. The intellectual merit directly applies to "stealthy" bloom initiation since the developing BenDiM biomass generally is unseen because it occurs below the first optical depth of satellite detection. BenDiM also is implicated in improved estimates of carbon export since this biomass may be missed during routine euphotic zone surveys and in trophic relationships since this biomass may benefit or harm grazers depending on the dinoflagellate species that dominates the niche at a given place and time. The broader impacts include: NCSU and UNCW graduate and undergraduate education; high school teacher education through COSEE; information transfer to colleagues at national/international meetings; and, information transfer to the public through a COSEE facilitated DVD on the cruise effort.