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

Frontiers in Marine Science

Marine Science

Mário A. P. Cachão¹  Jan-Berend Stuut²  Telmo Nunes³  Lluisa Cros⁴  Afonso Ferreira⁵  Vera Veloso⁵  Andreia Tracana⁵  Vanda Brotas⁶  Catarina Pinto⁷  Catarina V. Guerreiro⁸  Andrew P. Rees⁹  Alex Baker^1,10 

[1] Departament of Geology, Faculty of Sciences of the University of Lisbon, Lisbon, Portugal;Department of Ocean Systems, NIOZ Royal Netherlands Institute for Sea Research, Texel, Den Burg, Netherlands;Faculty of Earth and Life Sciences, Vrije Universiteit (VU), Amsterdam, Netherlands;Department of Plant Biology, Faculty of Sciences of the University of Lisbon, Lisbon, Portugal;Institut de Ciencies del Mar (CSIC), Passeig Marítim de la Barceloneta, Barcelona, Spain;Marine and Environmental Science Centre (MARE)/Aquatic Research Network (ARNET), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal;Marine and Environmental Science Centre (MARE)/Aquatic Research Network (ARNET), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal;Department of Plant Biology, Faculty of Sciences of the University of Lisbon, Lisbon, Portugal;Marine and Environmental Science Centre (MARE)/Aquatic Research Network (ARNET), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal;Instituto Dom Luiz (IDL), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal;Marine and Environmental Science Centre (MARE)/Aquatic Research Network (ARNET), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal;Instituto Dom Luiz (IDL), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal;Department of Plant Biology, Faculty of Sciences of the University of Lisbon, Lisbon, Portugal;Plymouth Marine Laboratory (PML), Plymouth, United Kingdom;School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom;

关键词: coccolithophores;    phytoplankton;    ecological gradients;    nutricline;    Westerly Wind Biome;    Trade Wind Biome;    Saharan dust;    Atlantic Meridional Transect;   

DOI  :  10.3389/fmars.2023.1119488

 received in 2022-12-08, accepted in 2023-03-06,  发布年份 2023

来源: Frontiers

【 摘 要 】

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.

【 授权许可】

Unknown   
Copyright © 2023 Guerreiro, Ferreira, Cros, Stuut, Baker, Tracana, Pinto, Veloso, Rees, Cachão, Nunes and Brotas