Origin and fate of long-chain polyunsaturated fatty acids in the Kerguelen Islands region (Southern Ocean) in late summer

IF 2.7 3区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY
Marine Remize , Frédéric Planchon , Ai Ning Loh , Fabienne Le Grand , Antoine Bideau , Eleonora Puccinelli , Aswani Volety , Philippe Soudant
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引用次数: 1

Abstract

Long-chain polyunsaturated fatty acids (LC-PUFA) are molecules produced at the basis of marine food webs and essential for ecosystem functioning. This study reports detailed fatty acid (FA) composition including the two LC-PUFA 20:5n-3 and 22:6n-3, in suspended organic matter (SPOM) from the upper 300 m collected in the Kerguelen Island region in the Southern Ocean during the post-bloom period (February–March 2018; project MOBYDICK). FA profiles were largely dominated by PUFA (53–69% of Total Fatty Acid, TFA) regardless of stations and among PUFA, proportions of LC-PUFA were especially high, making up 27–44% of TFA both in the ML and upper mesopelagic. 20:5n-3 and 22:6n-3 co-occurred in the ML as a result of the post-bloom phytoplankton community showing a mixed composition dominated by small size phytoplankton (prymnesiophytes and prasinophytes) supplying 22:6n-3, and with diatoms in lower proportions supplying 20:5n-3. Elevated levels of LC-PUFA were observed both inside the iron-fertilized area on the Kerguelen Plateau and downstream, and outside in High Nutrient Low Chlorophyll waters located upstream of the Plateau, and appeared unrelated to site. In the upper mesopelagic, both LC-PUFA were maintained at high relative proportions suggesting an efficient and possibly fast vertical transfer from the surface. Transfer with depth seems to proceed via distinct pathways according to LC-PUFA. 20:5n-3 may be exported along with diatoms, presumably in the form of large intact cells, aggregates as well as resting spores. For 22:6n-3, transfer may involve a channeling through the heterotrophic food web resulting in its association with fecal material at depth. Channeling of 22:6n-3 could involve heterotrophic protists such as dinoflagellates and ciliates grazing on small phytoplankton, as well as larger zooplankton such as copepods and salps, possibly feeding on microzooplankton and producing fecal pellets rich in 22:6n-3. According to LC-PUFA content, SPOM present throughout the upper water column (0–300 m) appeared of high nutritional quality both on- and off-plateau, and represented a valuable source of food for secondary consumers and suspension feeders.

夏末克尔盖伦群岛地区(南大洋)长链多不饱和脂肪酸的起源和命运
长链多不饱和脂肪酸(LC-PUFA)是在海洋食物网的基础上产生的分子,对生态系统功能至关重要。本研究详细报道了2018年2月至3月在南大洋克尔盖伦岛地区收集的300 m以上悬浮有机质(SPOM)中脂肪酸(FA)的组成,包括两种lcpufa 20:5n-3和22:6n-3。项目MOBYDICK)。无论站位如何,FA谱主要以PUFA为主(占总脂肪酸的53-69%),在PUFA中,LC-PUFA的比例特别高,在ML和上中系肌纤维中占27-44%。20:5n-3和22:6n-3在ML中同时出现,这是由于开花后浮游植物群落呈现出以小型浮游植物(prymnesiopophytes和prasinophytes)提供22:6n-3为主的混合组成,而硅藻的比例较低,提供20:5n-3。克尔格伦高原铁肥区及下游和高原上游高营养低叶绿素水域的LC-PUFA水平均出现升高,且与场地无关。在中上层,两种LC-PUFA保持在较高的相对比例,表明从表面进行有效且可能快速的垂直转移。根据LC-PUFA,深度转移似乎通过不同的途径进行。20:5n-3可能与硅藻一起输出,可能以完整的大细胞、聚集体和休眠孢子的形式输出。对于22:6n-3,转移可能涉及通过异养食物网的通道,导致其与深层粪便物质相关联。22:6 - n-3的通道可能涉及异养原生生物,如鞭毛虫和纤毛虫,它们以小型浮游植物为食,以及大型浮游动物,如桡足类和海鞘,它们可能以微型浮游动物为食,产生富含22:6 - n-3的粪便颗粒。根据LC-PUFA含量,SPOM在高原和非高原的上游水柱(0-300 m)均具有较高的营养质量,是次级消费者和悬浮饲料的宝贵食物来源。
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来源期刊
Journal of Marine Systems
Journal of Marine Systems 地学-地球科学综合
CiteScore
6.20
自引率
3.60%
发文量
81
审稿时长
6 months
期刊介绍: The Journal of Marine Systems provides a medium for interdisciplinary exchange between physical, chemical and biological oceanographers and marine geologists. The journal welcomes original research papers and review articles. Preference will be given to interdisciplinary approaches to marine systems.
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