Response of coccolithophore communities to oceanographic and atmospheric processes across the North- and Equatorial Atlantic-猫眼课题宝

DOI：

10.3389/fmars.2023.1119488

发表时间：

2023-04

期刊：

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其他

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作者：

C. Guerreiro;Afonso Ferreira;L. Cros;J. Stuut;A. Baker;Andreia Tracana;Catarina Pinto;V. Veloso;Andrew P. Rees;M. Cachão;Telmo Nunes;V. Brotas

颗石藻生产力因气候驱动的海洋变暖而发生的变化可能会产生级联的地球化学效应，反馈到不断变化的气候中。本文探讨了大规模的海洋和大气过程的作用（和相互作用），在北大西洋和赤道大西洋，包括撒哈拉沙漠的灰尘沉积，对分布的颗石群落。该研究基于在海洋透光区收集的生物和水文数据，以及在2018年北方秋季大西洋经向断面（AMT 28）期间从低层大气收集的气溶胶数据，与地球观测协同。研究结果证实了现有的理解，分布的颗石藻群落，这是相关的主要跨北大西洋的跨大西洋的水文梯度。动态的，含氧和microphytophyton-enriched沃茨在高纬度地区的特点是不太多样化的颗石植物种群，占主导地位的基板轴承r-选择颗石植物。相比之下，严重分层和picoclitton丰富的沃茨的亚热带环流揭示了更多样化的人口，占主导地位的伞形coccolithophores和holococcolithophores在表面，和floriform类群在较低的透光带。北大西洋热带环流区（北纬30-12°）的平均浓度为14.4×103个细胞/升，仅略低于北大西洋漂流区（北纬50-40°）的17.7×103个细胞/升，这为在高度分层的环流条件下产生颗石藻的重要性提供了一个快照视角。较高浓度的19 '-Hexanoyloxyfucoxanthin（HexFuco）的区域增强生产的r-选择的板石轴承物种表明，这种色素不应该被概括为整个颗石群落的代理。快速开花的Emiliania huxleyi和Gephyrocapsa oceanica以及蓝细菌（包括picoplankon和N2固定Trichodesmium spp.）在撒哈拉地区更持久的沙尘沉积区域的表面（约12-10°N），似乎是由沙尘携带的营养物质输入造成的。在这个分层的表层下，深层叶绿素最大值（DCM）的生产力增强似乎与表面上的生产力脱钩，由北大西洋热带营养线的地转向东变浅提供动力。由于这是最高的宏量营养素浓度的区域测量沿着和营养线下，我们的数据表明，东北热带大西洋可能作为一个永久的尘埃出生的营养沉积中心，如先前假设的。

Changes in coccolithophore productivity in response to climate-driven ocean warming are likely to have cascading biogeochemical effects that feed back to the changing climate. This paper investigates the role (and interplay) of large-scale oceanographic and atmospheric processes across the North- and Equatorial Atlantic, including Saharan dust deposition, on the distribution of coccolithophore communities. The study is based on biological and hydrological data collected across the photic zone of the ocean, and aerosol data collected from the lower atmosphere, across 50°N–1°S during the Atlantic Meridional Transect in boreal Autumn of 2018 (AMT28), in synergy with Earth Observations. Results confirm existing understanding of the distribution of coccolithophore communities which are related to major meridional hydrological gradients across the North Atlantic. Dynamic, oxygenated and microphytoplankton-enriched waters at higher-latitudes were characterized by less diverse coccolithophore populations, dominated by placolith-bearing r-selected coccolithophores. In contrast, the heavily stratified and picoplankton-enriched waters of the subtropical gyre revealed more diverse populations, dominated by umbelliform coccolithophores and holococcolithophores at the surface, and by floriform taxa in the lower photic zone. Mean concentrations of 14.4×103 cells/L present in the North Atlantic Tropical Gyre Province (30–12°N), only slightly lower compared to 17.7×103 cells/L produced in the North Atlantic Drift province (50–40°N), provide a snapshot perspective on the importance of coccolithophore production in heavily stratified gyre conditions. Higher concentrations of 19’-Hexanoyloxyfucoxanthin (HexFuco) in regions of enhanced production of r-selected placolith-bearing species suggest that this pigment should not be generalized as a proxy for the entire coccolithophore community. Enhanced abundances of fast-blooming Emiliania huxleyi and Gephyrocapsa oceanica, and of cyanobacteria (including both picoplankton and N2-fixing Trichodesmium spp.) at the surface of the region of more persistent Saharan dust deposition (at ~12-10°N) appeared to result from dust-born nutrient input. Underneath this stratified surface layer, enhanced productivity in the deep chlorophyll maximum (DCM) appeared decoupled from that on the surface, fueled by geostrophic eastward shoaling of the nutricline across the tropical North Atlantic. As this was the region of highest macronutrient concentrations measured along and below the nutricline, our data suggest that the NE tropical Atlantic may act as a permanent dust-born nutrient depocenter as previously hypothesized.

Response of coccolithophore communities to oceanographic and atmospheric processes across the North- and Equatorial Atlantic

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