Brassicasterol as a Biomarker in the Ross Sea

在南半球的春天，硅藻物种和南极洲的丛生裸子植物棕囊藻在罗斯海形成了大规模的水华。硅藻水华通常局限在罗斯海西部，而南极洲赤潮通常发生在罗斯海的东南部和中南部地区。最近的数据表明，非硅质浮游植物的优势，如南极微藻，可能是上一次冰川盛期大气二氧化碳减少的原因。拟议的项目将侧重于开发一种新的方法，以测试藻类甾醇--油菜籽甾醇--是否可以作为一种有用的沉积物生物标记物，用于描绘南极微藻在上覆水域中的相对丰度。来自这些地区的沉积物样本将被分析，以测试是否可以使用化合物特有的d13C方法来确定南极洲棕囊藻的相对丰度。具体地说，实验室培养物和岩心材料将被用来寻找耗尽的d13C沉淀物油菜甾醇信号。如果该方法在罗斯海被证明是有效的，那么它可以提供一些关于南极洲在冰川/间冰期边界上的潜在作用的明确答案。积极的结果可能会对包括生物地球化学家、生物海洋学家、古海洋学家和全球气候模型师在内的不同领域的科学家产生重要影响。

During the austral spring, diatom species and the colonial prymnesiophyte Phaeocystis antarctica form large blooms in the Ross Sea. The diatom blooms are typically localized in the western Ross Sea while the P. antarctica blooms typically develop in the southeastern and south central regions of the Ross Sea. Recent data suggest that the dominance of non-siliceous phytoplankton organisms, such as P. antarctica may be responsible for the drawdown in atmospheric CO2 that occurred during the last glacial maximum. The proposed project would focus on developing a new method to test whether the algal sterol, brassicasterol, could be a useful sediment biomarker for delineating the relative abundance of P. antarctica in over-lying waters. Sediment samples from each of these regions will be analyzed to test whether a compound-specific d13C method could be used to determine the relative abundance of Phaeocystis antarctica from over-lying waters. Specifically, laboratory cultures and core materials would be used to look for a depleted d13C sediment brassicasterol signal. If the method proves valid in the Ross Sea, then it could provide some definitive answers regarding the potential role of P. antarctica during the glacial/interglacial boundary. Positive results would be potentially important to a diverse array of scientists including: biogeochemists, biological oceanographers, paleoceanographers, and global climate modelers.