Collaborative Research SGER: Domoic acid toxins in the oceanic north Pacific in iron enrichment studies

该项目解决了与全球变暖有关的一个新问题：减少大气中温室气体水平的必要性。几十年前提出的一种解决方案是给广阔的、铁有限、高营养、低叶绿素(HNLC)的海洋区域施肥，吸收原本会与大气交换的二氧化碳。这种解决方案非常有吸引力，因为它的成本相对较低，而且有证据表明，铁肥确实促进了这些地区的浮游植物大量繁殖。然而，一些研究人员对可能会对生态系统的组成和功能产生意想不到的负面影响的铁剂疗法表示震惊。在这个项目中，研究人员假设，HNLC区域的铁肥会导致产生软骨藻酸(一种神经毒素)的假性菱形藻的生物量增加。HNLC地区DA增加的后果可能类似于在沿海地区观察到的后果，即这些生态系统中的捕食者受到污染，有时甚至死亡。探索性研究的一小笔赠款(SGER)是基于调查人员最近在拟菱形藻中发现DA的基础上提供的，这种藻经常在HNLC地区水域的铁浓缩实验中开花。研究人员开发了一种新的毒素检测方法，用于测定从亚北极西北太平洋HNLC水域采集的斑节对虾样本中的DA。这一SGER使研究人员能够参与2007年8月由NSF资助的一次研究巡航，测量沿HNLC(贫铁)地区的阿拉斯加湾(GOA)水域中的铁以及含有陆源铁的自然富集涡。研究人员将沿着果阿样带和在生长实验中测量相关的图尔迪格氏菌的丰度和DA水平，并确定与DA生产相关的假菱形藻物种。伪菱形藻的所有样本都将有相关的营养和海洋学数据，以提供海洋学和生理学背景下细胞DA配额的背景。这项研究的结果对于确定铁的富集度对生态系统的影响很重要。

The project addresses an emerging issue related to global warming: the necessity to reduce levels of greenhouse gases in the atmosphere. A solution proposed several decades ago is to fertilize the extensive, iron-limited, high nutrient, low chlorophyll (HNLC) regions of the sea, drawing down carbon dioxide that would otherwise exchange with the atmosphere. This solution is highly attractive due to its relatively low cost and evidence that iron fertilization does indeed promote phytoplankton blooms in such regions. Some researchers, however, have expressed alarm about the iron remedy that could result from unanticipated negative effects on the composition and functioning of ecosystems. In this project, the investigators hypothesize that iron fertilization of HNLC regions results in biomass increases of Pseudo-nitzschia that produce domoic acid (DA), a neurotoxin. The consequences of increased DA in HNLC areas could be like those observed in coastal regions, namely contamination and sometimes deaths of predators in those ecosystems. A Small Grant for Exploratory Research (SGER) is provided based on the investigators recent discovery of DA in Pseudo-nitzschia turdigula, which often blooms in iron enrichment experiments in waters of HNLC regions. The investigators developed a new toxin assay to measure DA in samples of P. turdigula collected from HNLC waters of the subarctic NW Pacific. This SGER enables the investigators to participate in an August 2007 NSF-funded research cruise measuring iron in waters of the Gulf of Alaska (GoA) along transects in HNLC (iron poor) regions and naturally enriched eddies containing terrestrially-derived iron. The investigators will measure the associated abundance and DA levels of P. turdigula along the GoA transect and in the grow-out experiments, and to determine the Pseudo-nitzschia species associated with DA production. All samples for Pseudo-nitzschia will have associated nutrient and oceanographic data to provide context for the cellular DA quotas in an oceanographic and physiological context. Results of the research are important in determining ecosystem effects iron enrichment.