Dinoflagellates as proxy indicators of marine environmental conditions in northern and southern high latitudes

本建议旨在研究鞭毛藻及其囊在不同地点和时间尺度的几个方面。鞭毛虫是单细胞原生生物，是世界海洋中重要的初级生产者。它们产生一个静止的囊肿，作为它们生命周期的一部分，以应对不利的条件。囊肿由一种高度耐腐蚀的聚合物组成，这使得它们在沉积物中完好无损地保存了数百万年。鞭毛藻是造成有害藻华或“赤潮”的主要原因，它会导致人类慢性疾病，杀死鱼类和海洋哺乳动物，并导致加拿大水产养殖业每年损失数百万美元的收入。它们也很容易在船舶的压载舱中运输，当压载舱在目的地清空时，它们会殖民到新的环境，经常在新的地区带来有毒的赤潮。尽管如此，它们的囊肿构成了极好的古海表条件指标，它们被用来定量地重建最近地质历史的海表条件。在这里，我们提出了7个使用鞭毛藻或其囊肿作为主要工具的项目。其中一个项目旨在重建加拿大北极海面条件的演变，特别是海冰和初级生产力的演变。重建的重点是过去2000年，以便了解在最近的地质历史中，在温暖或寒冷的气候条件下，初级生产力是如何变化的。该项目还旨在研究可能被洋流或船只带到北极的潜在有毒物种的囊肿。另一个项目旨在描述在北极表层沉积物中发现的两个新物种。形态学描述将被完成，这些囊肿将被分配一个正式的物种名称，它们的遗传密码将被测序，以帮助将来识别它们。其中一个项目涉及新斯科舍省哈利法克斯港有毒物种的囊肿。将对这些囊肿进行基因测序，以验证其毒性，并查看该地区是否存在有毒红潮的潜在危险。研究人员还将研究一个短沉积物岩心，以确定这些囊肿是在该地点自然发生的，还是由船只从其他地方运来的，因此被认为是入侵物种。阿根廷的圣乔治湾也将进行类似的研究。在那里，我们将观察地表沉积物中的囊肿，以估计有毒赤潮的风险，并观察短沉积物芯，以确定是否有物种被运送到那里，还是自然发生。下一个项目包括一个高度创新的方法来研究囊肿或运动形式，或任何其他海洋微生物。我们正在使用微型和纳米ct扫描，它使用X射线产生图像来可视化鞭毛藻。据我们所知，这是第一次用X射线成功扫描如此小的生物体。当这项技术得到完善后，它可以在不接触鞭毛藻的情况下，从各个角度观察鞭毛藻的内外，也可以在不使用化学物质处理样本的情况下观察浮游生物或沉积物样本中的任何海洋生物，而且精度与最强大的显微镜一样高。扫描也会产生非常酷的图像！最后，我们将研究鞭毛藻包囊的化学成分，试图找出它们是由什么组成的，以及为什么它们如此具有抵抗力。如果我们成功了，我们应该能够复制这种成分来制造超耐药的纳米材料。我们还计划利用这些囊肿的化学成分来了解它们生活的环境条件，从而记录过去的气候。

This proposal aims at studying several aspects of dinoflagellates and their cysts at various locations and timescales. Dinogflagellates are unicellular protists that are important primary producers in the World oceans. They produce a resting cyst as part of their life cycle in response to adverse conditions. The cyst is composed of a highly resistant polymer that allows them to be preserved intact for millions of years in the sediments. Dinoflagellates are notably responsible for harmful algal blooms, or "red tides", which cause chronic illness to humans, kill fish and marine mammals and cause the loss of millions of dollars in revenue to the Canadian aquaculture industry each year. They are also famous because they are easily transported in ballast tanks of ships and colonize new environments when the ballast tanks are emptied at the ship destination, often bringing toxic red tides in new areas. Despite that, their cysts constitute excellent paleo-indicators of sea surface conditions and they are used to quantitatively reconstruct sea surface conditions of the recent geological past. Here we present 7 projects that use dinoflagellates or their cysts as the main tool. One project aims at reconstructing the evolution of sea surface conditions in the Canadian Arctic, notably with respect to sea ice and primary productivity. The reconstruction focuses on the last 2000 years in order to understand how the primary productivity has changed in the recent geological past during warmer or colder climate conditions. The project also aims at looking at cysts of potentially toxic species that may have been transported in the Arctic by oceanic currents or by ship. Another projects aims at describing two new species discovered in Arctic surface sediments. A morphological description will be done, the cysts will be assigned a formal species name and their genetic code will be sequenced to help identifying them in the future. One project deals with the cysts of a toxic species in the Port of Halifax, Nova Scotia. Genetic sequencing of the cysts will be done to verify their toxicity and see if there is potential danger of toxic red tide in the area. A short sediment core will also be studied to find out if the cysts occur in that location naturally, or if they were transported from somewhere else by ships, therefore being considered as an invasive species. A similar study will take place in the Gulf of San Jorge in Argentina. There we will look at cysts in surface sediments to estimates the risks of toxic red tides, and look at short sediment cores to find out if anyone species present was transported there or if it occurs naturally. The next project consists of a highly innovative approach to study the cysts or the motile forms, or any other marine micro-organsims. We are using micro- and nano-CT-Scans, which use X rays to produce images to visualize the dinoflagellate. To our knowledge, this is the first time that such small organisms are successfully scanned with X rays. When perfected, the technique will allow observing dinoflagellates inside and out and from every angles without touching them, or any marine organism in plankton or sediment samples without having to use chemicals to process the samples and with the same precision as the most powerful microscope. And the scans produce very cool images too! Finally we will be studying the chemical composition of dinoflagellate cysts to try and find out what they are made of and why they are so resistant. If we are successful, we should be able to replicate this composition to create ultra-resistant nanomaterials. We are also planning to use the chemical composition of the cysts to find out about the environmental conditions in which they lived, therefore documenting past climates.