Brassicasterol as a Biomarker in the Ross Sea

在南方的春天，硅藻种类和殖民地原水藻Phaeocystis antarctica在罗斯海形成大规模的水华。硅藻华通常局限于罗斯海西部，而南极藻华通常发育在罗斯海的东南部和中南部地区。最近的数据表明，非硅质浮游植物生物的优势，如南极浮游植物，可能是末次盛冰期发生的大气二氧化碳减少的原因。拟议中的项目将侧重于开发一种新方法，以测试藻类甾醇（芸苔甾醇）是否可以作为一种有用的沉积物生物标志物，用于描绘上覆水域南极南极藻的相对丰度。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特定化合物的d13C方法来确定来自上覆水域的南极褐囊藻的相对丰度。具体来说，实验室培养物和岩心材料将用于寻找耗尽的d13C沉积物油菜甾醇信号。如果该方法在罗斯海被证明是有效的，那么它就可以为南极南极冰在冰期/间冰期边界的潜在作用提供一些明确的答案。积极的结果可能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建模者在内的各种科学家都很重要。

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.