The Influence of Cobalt and Cadmium Speciation on Marine Cyanobacteria in the Costa Rica Upwelling Dome and at Station Aloha

虽然铁对浮游植物生长的影响已被广泛研究，但对钴、镉和锌等其他微量金属的影响的研究相对较少。伍兹霍尔海洋研究所的一位科学家根据培养研究的结果推测，微量元素的相对丰度和种类的变化可能会影响浮游植物组合的组成，这些研究表明，微量元素的浓度会导致生长速度的差异。为了验证这一假设，研究人员计划在太平洋的两个地点检查钴和镉物种对聚球菌和鳄鱼的影响。此外，他将确定钴在东赤道太平洋横断面上的分布，以提高我们对钴的全球生物地球化学循环的理解。为了实现这些目标，科学家将开发和校准镉形态形成方法，测量垂直剖面上的钴和镉形态，分析与镉和钴形态相关的蓝藻丰度，进行生理实验以确定固氮蓝藻对钴和锌限制和镉毒性的敏感性。分析聚球菌中金属酶的功能基因表达，评估鳄鱼细胞数量和固氮基因表达的变化。

ABSTRACTOCE-0327225While the influence of iron on phytoplankton growth has been the subject of extensive investigations, comparatively little work has been conducted on the influence of other trace metals such as cobalt, cadmium and zinc. Building on results from culture studies indicating differences in growth rates depending on trace metal concentrations, a scientist from Woods Hole Oceanographic Institution hypothesizes that shifts in relative abundances and speciation of trace elements could influence the composition of phytoplankton assemblages. To test the hypothesis, the investigator plans to examine the influence of cobalt and cadmium speciation on Synechococcus and Crocosphaera at two sites in the Pacific Ocean. In addition, he will determine the distribution of cobalt across transects in the Eastern Equatorial Pacific to improve our understanding of the global biogeochemical cycle of cobalt. To attain these goals, the scientist will develop and calibrate a cadmium speciation method, measure cobalt and cadmium speciation on vertical profiles, analyze cyanobacterial abundances relative to cadmium and cobalt speciation, conduct physiological experiments to determine the sensitivity of nitrogen fixing cyanobacteria to cobalt and zinc limitations and cadmium toxicity, analyze functional gene expression of metalloenzymes in Synechococcus and assess changes in cell number of Crocosphaera and nitrogen fixation gene expression.