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

该项目解决了一个与全球变暖相关的新问题：降低大气中温室气体水平的必要性。几十年前提出的一个解决方案是对海洋中广泛的、铁含量有限的、高营养、低叶绿素（HNLC）的区域进行施肥，从而吸收二氧化碳，否则二氧化碳将与大气交换。这一解决方案极具吸引力，因为其成本相对较低，而且有证据表明，铁施肥确实会促进这些地区的浮游植物大量繁殖。然而，一些研究人员对铁疗法可能对生态系统的组成和功能产生意想不到的负面影响提出了警告。在这个项目中，研究人员假设，在HNLC区域施用铁肥导致产生软骨藻酸（DA）的伪nitzschia生物量增加，这是一种神经毒素。低海拔地区的自然灾害增加的后果可能与沿海地区的情况类似，即这些生态系统中的捕食者受到污染，有时甚至死亡。由于研究人员最近在高铁区水体富铁实验中发现了大量繁殖的turdigula伪nitzschia DA，因此获得了探索性研究（SGER）小额资助。研究人员开发了一种新的毒素测定方法，以测量从西北太平洋亚北极HNLC水域收集的P. turdigula样品中的DA。该SGER使研究人员能够参加2007年8月由美国国家科学基金会资助的一项研究巡航，测量阿拉斯加湾（GoA）水域的铁，沿着HNLC（缺铁）地区的横断面和含有陆源铁的自然富集漩涡。研究人员将在GoA样带和生长实验中测量P. turdigula的相关丰度和DA水平，并确定与DA产生相关的伪尼茨氏菌物种。伪nitzschia的所有样本将具有相关的营养和海洋学数据，以便在海洋学和生理学背景下为细胞DA配额提供背景。研究结果对确定铁富集对生态系统的影响具有重要意义。

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.