Diapause

滞育

• 批准号: NE/J006718/1
• 负责人: Ray Leakey
• 金额: $ 4万
• 依托单位: Scottish Association For Marine Science
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ006718%2F1
• 关键词: Diapause

Non-technical summary Calanoid copepods are key players in World's oceans. They are the largest constituent of oceanic zooplankton biomass and are a major link within global carbon cycles. In the North Atlantic and Arctic, calanoid copepods are a vital food for commercially important fish species such as cod, mackerel and herring. A key feature of many calanoid copepod life-cycles is a phase of overwintering at great depth, in a state analogous to hibernation. This increases their chances of surviving to the next season through avoiding predation at times when there is little else to be gained by remaining within the surface layers. A notable feature of calanoid copepods is that they contain exceptionally high amounts of fat (or lipid). The large lipid store is both a valuable energy reserve and a major determinant of buoyancy. The attainment of neutral buoyancy is important to copepods over winter since they must minimise swimming effort in order to save energy. A balance must be sought between provisioning for the winter without disturbing the ability of the copepod to achieve neutral buoyancy. The best scientific efforts at trying to simulate this balance have so far proved to be unsatisfactory. Recently, two potential additional mechanisms of buoyancy control have been identified. In one study, Sartoris and colleagues found that diapausing copepods contained a different balance of ions in their bodily fluids (haemolymph) compared to active, surface dwelling copepods. In a second study, scientists involved in the present proposal showed that lipids rich in omega-3 polyunsaturated fatty acids (PUFAs) changed from liquid to solid state when under pressures typical of the deep sea. The effect only happened when PUFAs comprised more than 50% of the lipid store which, coincidentally, was commonly found in deep diapausing copepods, but not in those still active at the surface. At present, both of the mechanisms have only been identified in Southern Ocean copepods, although previously 'misinterpreted' evidence in the scientific literature also suggests that northern hemisphere species employ similar techniques. We will carry out surveys across a number of locations in the North Atlantic, Arctic and adjacent sea-lochs to determine lipid composition and haemolymph-ion concentrations in three calanoid copepod species. The surveys take into account environmental influences, particularly the type and availability of the microplanktonic food of copepods. This will determine whether there is any active regulation of the levels of omega-3 fatty acids in the lipid stores. Such active regulation may be of particular importance towards the end of winter as a means of controlling the timing and rate of ascent back into the surface layers. Our sampling strategy, application of novel analytical techniques and datasets generated during the research will allow these questions to be addressed. Secondly, using statistical techniques we will reconsider efforts made so far to simulate overwintering depth and seek improvements through including additional data and mechanisms. For instance, in changing from a liquid to solid state, the volume occupied by a lipid will be decreased and its response to increasing pressure will change. The effects of ionic balance will also be considered, mainly in how it may assist copepods maintain their theoretical neutral buoyancy depth in the face of any physical disturbance. This research proposal is based on our recent discovery, that the biophysical properties of lipids are a major factor controlling the distribution of life in the oceans. This finding gives an exciting new perspective on the role of lipids in marine organisms, opening up a fundamentally new direction for research, with profound implications for our understanding of the entire ocean food web.

非技术摘要calanoid copepods是世界海洋中的主要参与者。它们是海洋浮游生物生物量最大的组成部分，并且是全球碳周期中的主要联系。在北大西洋和北极，calanoid copods是鳕鱼，鲭鱼和鲱鱼等商业重要鱼类的重要食物。许多Calanoid Copepod Life-Cycles的关键特征是在类似于冬眠的状态下深度越冬的阶段。这增加了他们通过避免捕食的机会，有时会避免捕食，而在表面层中几乎没有其他东西可以获得。 cananoid copepods的一个值得注意的特征是它们含有极高的脂肪（或脂质）。大型脂质商店既是宝贵的能源储备，又是浮力的主要决定因素。在冬季，中性浮力对于copepods很重要，因为它们必须最大程度地减少游泳工作以节省能源。必须在为冬季提供的供应之间寻求平衡，而不会扰乱Copepod实现中性浮力的能力。迄今为止，试图模拟这种平衡的最佳科学努力被证明是不令人满意的。最近，已经确定了两个潜在的浮力控制机制。在一项研究中，Sartoris及其同事发现，与主动的表面居住Copepods相比，育育copepods copepods的体液（血液隔淋巴）中的离子平衡不同。在第二项研究中，参与本提案的科学家表明，富含omega-3多不饱和脂肪酸（PUFAS）的脂质在典型的深海压力下，从液体变为固态。这种效果只有在Pufas占脂质店的50％以上时才发生，偶然地在深处的毛发状copepods中发现，但在表面仍然活跃的脂质copepods中没有发现。 目前，这两种机制仅在南大洋copods中被鉴定出来，尽管以前在科学文献中“误解”证据也表明北半球物种采用了相似的技术。我们将在北大西洋，北极和邻近的海绵中进行多个位置进行调查，以确定三种钙的copepod物种中的脂质组成和乙糖蛋白浓度。这些调查考虑了环境的影响，尤其是Copepods微量膨胀食品的类型和可用性。这将确定脂质储存中omega-3脂肪酸水平是否存在任何主动调节。这种主动调节在冬季结束时可能特别重要，这是控制恢复到地面层的时机和上升速率的一种手段。我们的抽样策略，在研究期间生成的新分析技术和数据集的应用将允许解决这些问题。 其次，使用统计技术，我们将重新考虑迄今为止为模拟越冬的深度所做的努力，并通过包括其他数据和机制来寻求改进。例如，在从液体变为固态时，脂质占据的体积将减少，其对压力增加的反应将改变。还将考虑离子平衡的影响，主要是在面对任何身体障碍的情况下如何帮助copepods保持其理论中性浮力深度。 这项研究建议是基于我们最近的发现，即脂质的生物物理特性是控制海洋生命分布的主要因素。这一发现使人们对脂质在海洋生物中的作用有一个令人兴奋的新观点，从根本上为研究开辟了一个新的方向，对我们对整个海洋食品网的理解产生了深远的影响。