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

甲藻作为北部和南部高纬度地区海洋环境条件的代理指标

• 批准号: RGPIN-2014-05609
• 负责人: Rochon, André
• 金额: $ 2.19万
• 依托单位: Université du Québec à Rimouski
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=611734
• 关键词: Dinoflagellates; proxy; indicators; marine; environmental

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.

该提案旨在研究不同地点和时间尺度的甲藻及其包囊的多个方面。甲藻是单细胞原生生物，是世界海洋中重要的初级生产者。作为生命周期的一部分，它们会产生休眠囊肿，以应对不利条件。囊肿由高抵抗力的聚合物组成，使它们能够在沉积物中完好无损地保存数百万年。甲藻是造成有害藻华或“赤潮”的罪魁祸首，赤潮会给人类带来慢性疾病，杀死鱼类和海洋哺乳动物，并每年给加拿大水产养殖业造成数百万美元的收入损失。它们之所以出名，还因为它们很容易在船舶压载舱中运输，当船舶目的地的压载舱清空时，它们会在新的环境中定居，经常在新的地区带来有毒的赤潮。尽管如此，它们的包囊构成了海面条件的极好的古指标，并且它们被用来定量重建最近地质历史的海面条件。在这里，我们展示了 7 个使用甲藻或其包囊作为主要工具的项目。其中一个项目旨在重建加拿大北极地区海面条件的演变，特别是海冰和初级生产力方面。重建的重点是过去 2000 年，以便了解在较温暖或较寒冷的气候条件下，最近的地质历史中初级生产力如何变化。该项目还旨在研究可能通过洋流或船舶在北极运输的潜在有毒物种的包囊。另一个项目旨在描述在北极表面沉积物中发现的两种新物种。将进行形态学描述，为包囊指定正式的物种名称，并对它们的遗传密码进行测序，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包囊。将对包囊进行基因测序，以验证其毒性，并了解该地区是否存在有毒赤潮的潜在危险。还将研究一个短的沉积物核心，以确定包囊是否自然发生在该位置，或者它们是否是通过船只从其他地方运输来的，因此被视为入侵物种。类似的研究将在阿根廷圣豪尔赫湾进行。在那里，我们将观察表层沉积物中的包囊，以估计有毒赤潮的风险，并观察短沉积物岩心，以确定是否存在任何物种被迁移到那里或是否自然发生。下一个项目包括一种高度创新的方法来研究包囊或运动形式或任何其他海洋微生物。我们正在使用微米和纳米 CT 扫描，它使用 X 射线生成图像来可视化甲藻。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。完善后，该技术将允许在不接触甲藻的情况下从各个角度观察甲藻，或浮游生物或沉积物样本中的任何海洋生物，而无需使用化学物质处理样本，并且具有与最强大的显微镜相同的精度。扫描也会产生非常酷的图像！最后，我们将研究甲藻包囊的化学成分，试图找出它们的成分以及它们为何如此具有抵抗力。如果我们成功了，我们应该能够复制这种成分来制造超耐磨的纳米材料。我们还计划利用包囊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。