Quantifying the contribution of sympagic versus pelagic diatoms to Arctic food webs and biogeochemical fluxes (SYM-PEL)

量化共生硅藻与远洋硅藻对北极食物网和生物地球化学通量的贡献 (SYM-PEL)

• 批准号: NE/S002480/1
• 负责人: Simon Belt
• 金额: $ 24.85万
• 依托单位: Plymouth University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FS002480%2F1
• 关键词: Quantifying; contribution; sympagic; versus; pelagic

At the base of the Arctic food web, there are three major primary producers: small flagellates, diatoms living in open water (pelagic) and diatoms growing in sea ice (sympagic). The role of the sea ice diatoms is perceived differently across the research community. For ecologists they are central to the polar ecosystem, while those looking at global ocean scales consider them less important and have not incorporated them into their models projecting climate change feedbacks. This may reflect their minor (<10%) contribution to the total primary production in Arctic waters. However, two newly developed trophic marker approaches that can trace diatoms from sea ice and open water within the food web, consistently find a strong ice algae 'signal' in polar consumers. Even in whales, seals and polar bears, as much as 80% of their body fat reserves are from carbon originally fixed by ice algae. How is this possible? How will this change in a warming Arctic? Our project aims to answer this puzzle and to bridge the gap between the contrasting perceptions of ice algae.We propose to quantify the relative importance of ice algae vs. open water diatoms for consumers living in the high Arctic - considering different species, regions and times of the year. We will also look at material that sinks to the seabed, and is collected in sediment traps. Our first hypothesis is that the input of ice algae to Arctic food webs and to export fluxes is disproportionately higher than their contribution to total primary production. Our second hypothesis examines the mechanisms behind these energy transfers, focussing on the more subtle concept of food benefit. It is not just the total annual amount of food that matters; it also has to arrive at the right time, be accessible and be nutritious. To test these hypotheses, we have developed a method based on "Highly Branched Isoprenoids" (HBIs). These lipid molecules are specific to a series of diatom species specific either to sea ice or open water. Using the ratio of ice-versus water column-derived HBIs, we can now trace the relative roles of these energy inputs to the food web. The chemical stability of these molecules as they pass through the food web is a key advantage of this tracer method, as previously it has been very difficult to follow the fate of ice- or water column derived algae.We propose to take part in an ice drift across the Central Arctic Ocean (MOSAiC) that will give the opportunity to sample the foodweb and material from sediment traps for subsequent HBI analysis in our lab in Plymouth. We will also determine the body condition of various consumers as an integrator of net benefit derived from each food type over the season. The cruise data set will be complemented with data from other Arctic expeditions and those estimated with a second, independent diet method by our Project partners. This will give a pan-Arctic overview of the importance of ice algae to the lipid stores of key consumers. Then, simulation model outputs of future climate projection will allow scaling up to the whole Arctic Basin. First, we will work with Project partners modelling life cycles of key zooplankton species, to estimate their potential to colonise a future, more ice-free central Arctic Ocean. Second, we will use NEMO-MEDUSA - the oceanic component of the UK's Earth system model (UKESM1) - to determine whether projected increases in pelagic primary production could compensate for loss of ice algae as a food source for zooplankton. Our findings, and those of other participants in MOSAiC, will be used to initiate a "roadmap" for the incorporation of ice algae into NEMO-MEDUSA. By helping to bridge between the physical, biogeochemical and ecological functions of sea ice and requirements of large-scale modelling, we aim to improve our understanding of the changing Arctic and its provision of services to mankind.

在北极食物网的底层，有三种主要的初级生产者：小型鞭毛虫、生活在开阔水域的硅藻（远洋）和生长在海冰中的硅藻（深海硅藻）。海冰硅藻的作用在整个研究界都有不同的看法。对于生态学家来说，它们是极地生态系统的核心，而那些关注全球海洋尺度的人则认为它们不那么重要，并且没有将它们纳入预测气候变化反馈的模型中。这可能反映了它们对北极沃茨总初级生产力的贡献较小（<10%）。然而，两种新开发的营养标记方法，可以跟踪硅藻从海冰和开放水域的食物网，始终发现一个强大的冰藻“信号”在极地消费者。即使在鲸鱼、海豹和北极熊中，它们身体脂肪储备的80%也来自最初由冰藻固定的碳。这怎么可能？在北极变暖的情况下，这将如何改变？我们的项目旨在回答这个难题，并弥合冰藻对比认知之间的差距。我们建议量化冰藻与开放水域硅藻对生活在北极高纬度地区的消费者的相对重要性-考虑不同的物种，地区和一年中的不同时间。我们还将研究沉入海底的物质，并在沉积物收集器中收集。我们的第一个假设是，冰藻的北极食物网和出口通量的输入是不成比例地高于其对总初级生产的贡献。我们的第二个假设研究了这些能量转移背后的机制，重点是更微妙的食物益处概念。重要的不仅仅是每年的粮食总量;粮食还必须在正确的时间到达，可以获得和有营养。为了验证这些假设，我们开发了一种基于“高度支化类异戊二烯”（HBI）的方法。这些脂质分子是一系列硅藻物种所特有的，这些硅藻物种在海冰或开放水域中都是特有的。利用冰与水柱衍生的HBIs的比率，我们现在可以追踪这些能量输入对食物网的相对作用。这些分子在通过食物网时的化学稳定性是这种示踪方法的一个关键优势，由于以前一直很难跟踪冰或水柱衍生藻类的命运，我们建议参加穿越北冰洋中部的冰漂流（MOSAiC）这将使我们有机会从沉积物收集器中对食物网和物质进行采样，以便在普利茅斯的实验室进行后续的HBI分析。我们还将确定不同消费者的身体状况，作为季节内每种食物类型的净收益的综合者。巡航数据集将与来自其他北极探险的数据以及我们的项目合作伙伴使用第二种独立饮食方法估计的数据进行补充。这将提供冰藻对主要消费者脂质储存的重要性的泛北极概述。然后，未来气候预测的模拟模型输出将允许扩大到整个北极盆地。首先，我们将与项目合作伙伴合作，对主要浮游动物物种的生命周期进行建模，以估计它们在未来更无冰的北冰洋中部殖民的潜力。其次，我们将使用NEMO-MEDUSA -英国地球系统模型（UKESM 1）的海洋部分-来确定浮游生物初级生产的预计增加是否可以补偿作为浮游动物食物来源的冰藻的损失。我们的研究结果，以及MOSAiC的其他参与者的研究结果，将用于启动将冰藻纳入NEMO-MEDUSA的“路线图”。通过帮助在海冰的物理、地球化学和生态功能与大规模建模要求之间架起桥梁，我们的目标是提高我们对北极变化及其为人类提供服务的理解。

项目成果

Multiple Trophic Markers Trace Dietary Carbon Sources in Barents Sea Zooplankton During Late Summer

• DOI: 10.3389/fmars.2020.610248
• 发表时间: 2021-01
• 作者: D. Kohlbach;H. Hop;A. Wold;K. Schmidt;L. Smik;S. Belt;Amalia Keck Al-Habahbeh;M. Woll;M. Graeve;A. Dabrowska;A. Tatarek;A. Atkinson;P. Assmy

A multi-trophic marker approach reveals high feeding plasticity in Barents Sea under-ice fauna

多营养标记方法揭示了巴伦支海冰下动物群的高摄食可塑性

• DOI: 10.1016/j.pocean.2022.102895
• 发表时间: 2022
• 期刊: Progress in Oceanography
• 影响因子: 4.1
• 作者: Kohlbach D

Winter Carnivory and Diapause Counteract the Reliance on Ice Algae by Barents Sea Zooplankton

冬季食肉和滞育抵消了巴伦支海浮游动物对冰藻的依赖

• DOI: 10.3389/fmars.2021.640050
• 发表时间: 2021
• 期刊: Frontiers in Marine Science
• 影响因子: 3.7
• 作者: Kohlbach D