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: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567276
• 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.

该建议旨在研究不同地点和时间尺度的甲藻及其孢囊的几个方面。沟鞭藻是单细胞原生生物，是世界海洋中重要的初级生产者。它们产生一个休眠的囊肿作为其生命周期的一部分，以应对不利的条件。这种包囊由一种高抗性聚合物组成，使它们能够在沉积物中完整地保存数百万年。甲藻是造成有害藻华或“赤潮”的主要原因，赤潮给人类造成慢性疾病，杀死鱼类和海洋哺乳动物，每年给加拿大水产养殖业造成数百万美元的收入损失。它们也很有名，因为它们很容易在船舶的压载舱中运输，当压载舱在船舶目的地清空时，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，它们的孢囊构成了海洋表面状况的良好古指标，它们被用来定量重建最近地质历史的海洋表面状况。在这里，我们提出了7个项目，使用甲藻或其孢囊作为主要工具。其中一个项目的目的是重建加拿大北极地区海面状况的演变，特别是海冰和初级生产力。重建的重点是过去2000年，以了解在最近的地质过去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层沉积物中发现的两个新物种。将进行形态学描述，孢囊将被分配一个正式的物种名称，它们的遗传密码将被测序，以帮助在未来识别它们。其中一个项目涉及新斯科舍省的哈利法克斯港的一种有毒物种的包囊。将对这些包囊进行基因测序，以验证它们的毒性，并确定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芯，以查明包囊是否自然地发生在该位置，或者它们是否是由船只从其他地方运来的，因此被认为是入侵物种。类似的研究将在阿根廷的圣豪尔赫湾进行。在那里，我们将研究表层沉积物中的孢囊，以估计有毒赤潮的风险，并研究短沉积物芯，以确定是否有任何物种被转移到那里，或者是否是自然发生的。下一个项目包括一个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。我们正在使用微型和纳米CT扫描，它使用X射线产生图像来可视化甲藻。据我们所知，这是第一次成功地用X射线扫描这种小生物。完善后，该技术将允许从各个角度观察腰鞭毛虫，而无需接触它们，或浮游生物或沉积物样品中的任何海洋生物，而无需使用化学品来处理样品，并具有与最强大的显微镜相同的精度。扫描也产生非常酷的图像！最后，我们将研究甲藻孢囊的化学成分，试图找出它们是由什么组成的，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组合物来创造超耐纳米材料。我们还计划利用孢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。