How do Arctic microalgae thrive in the chaotic light field of in-ice and under-ice marine habitats?

北极微藻如何在冰内和冰下海洋栖息地的混乱光场中繁衍生息？

• 批准号: RGPIN-2020-06384
• 负责人: Babin, Marcel
• 金额: $ 5.46万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=717671
• 关键词: How; do; Arctic; microalgae; thrive

Marine polar environments are, for photosynthesising organisms, among the most extreme in terms of variations in light. From the polar night to the midnight sun, and from ice-free to ice-covered conditions, microalgae have evolved to outlive sustained lacks and excesses of photons. How polar microalgae survive prolonged darkness, grow at extremely low levels of light, cope with wide and rapid fluctuations, and tolerate excess irradiance remain poorly understood. My research programme will address the following questions: 1) What is the minimum light level at which ice algae and phytoplankton can achieve net growth during early to mid-winter? 2) How is light distributed inside the sea-ice matrix, together with nutrients and grazers, and how does this distribution relates to sea-ice microphysics? 3) How is the under-ice dynamic light regime shaped by various macroscopic features of sea ice (snow-pack heterogeneity and metamorphism, ridges, leads, ice age, melt ponds)? 4) How do phytoplankton respond to this highly fluctuating light regime in terms of gross primary production? 5) Considering also grazing and other loss processes, which dynamic light regime is most favourable for biomass accumulation (bloom) under sea ice? 6) How to properly account for small- and medium-scale light fluctuations when estimating primary production at large scale using remote-sensing data? 7) What are the consequences, on un-der-ice primary production, of the ongoing modifications of sea ice in the Arctic? This Discovery Grant research program will include laboratory experiments, field activities, and the development of upscaling methods for large-scale remote-sensing applications. The laboratory experiments will aim at determining: 1) the minimum light requirement for microalgae growth in conditions typical of the sea-ice matrix and the upper-water column during late winter and early spring, and 2) how polar microalgae cope with wide and rapid fluctuations in light and how the light variation and limitation ultimately affect growth. During the field expeditions, new miniaturised optical sensors and imaging systems mounted onto an ad hoc endoscope will be used to document the optical, physical and chemical properties that shape the micro-scale environment of ice algae. Also, various autonomous platforms (drones, autonomous underwater vehicles and remotely operating vehicles) will be used to describe the under-ice light field at scales ranging from the metre to several kilometres, and we will determine the space and time response of primary production to the broad spectrum of observed light variations. Finally, new upscaling approaches will be developed to appropriately account for small- and medium-scale features of sea ice that affect light and primary production at large scale during all seasons. The new approaches will be applied on remote-sensing data to determine multiyear trends in pan-Arctic primary production, including the under-ice contribution.

对于光合生物来说，海洋极地环境是光线变化最极端的环境之一。从极夜到午夜的太阳，从无冰到冰层覆盖的条件下，微藻已经进化到比持续缺乏和过度的光子更长寿。极地微藻如何在长时间的黑暗中生存，在极低的光照下生长，科普广泛而快速的波动，以及耐受过度的辐照度，仍然知之甚少。我的研究计划将解决以下问题：1）冰藻和浮游植物在初冬至仲冬期间能够实现净生长的最低光照水平是多少？2)光是如何分布在海冰矩阵，连同营养物质和食草动物，以及如何这种分布与海冰微物理？3)海冰的各种宏观特征（积雪的异质性和变质作用、山脊、铅、冰河时代、融化池）是如何塑造冰下动态光态的？4)浮游植物在总初级生产力方面如何应对这种高度波动的光照状况？5)还考虑放牧和其他损失过程，动态光制度是最有利于生物量积累（水华）下海冰？6)在利用遥感数据估算大规模初级生产时，如何适当考虑中小规模的光照波动？7)北极海冰的持续变化对冰下初级生产有什么影响？ 这项发现补助金研究计划将包括实验室实验、现场活动以及开发大规模遥感应用的升级方法。实验室实验的目的是确定：1）在冬季末和春季初海冰基质和上层水柱的典型条件下微藻生长的最低光照要求，以及2）极地微藻如何科普光照的广泛和快速波动以及光照变化和限制最终如何影响生长。在实地考察期间，安装在特设内窥镜上的新型光学传感器和成像系统将用于记录塑造冰藻微尺度环境的光学，物理和化学特性。此外，各种自主平台（无人驾驶飞机、自主水下航行器和遥控潜水器）将用于描述冰下光场，尺度从米到几公里不等，我们将确定初级生产对观测到的广泛光变化的空间和时间响应。最后，将开发新的尺度放大方法，以适当考虑海冰的中小尺度特征，这些特征在所有季节都会大规模影响光照和初级生产。将对遥感数据采用新的方法，以确定泛北极初级生产的多年趋势，包括冰下的贡献。