Seasonal and Geographical Transitions in Eukaryotic Phytoplankton Community Structure in the Atlantic and Pacific Oceans

Choi, Chang Jae; Jiménez, Valeria; Needham, David M.; Poirier, Camille; Bachy, Charles; Alexander, Harriet; Wilken, Susanne; Chávez, Francisco P.; Sudek, Sebastian; Giovannoni, Stephen J.; Worden, Alexandra Z.

doi:10.3389/fmicb.2020.542372

Cited by 37 publications

(78 citation statements)

References 102 publications

(216 reference statements)

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“…A dynamic ecological system underlies the annual cycle of phytoplankton biomass in the western North Atlantic. Phytoplankton composition has been observed to undergo major seasonal shifts (Choi et al, 2020;Kramer et al, 2020;Yang et al, 2020). Communities dominated by cyanobacteria, prasinophytes and pelagophytes in the early winter give way to a more diverse eukaryotic phytoplankton community in the spring.…”

Section: Introductionmentioning

confidence: 99%

Seasonality of the Microbial Community Composition in the North Atlantic

et al. 2021

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Planktonic communities constitute the basis of life in marine environments and have profound impacts in geochemical cycles. In the North Atlantic, seasonality drives annual transitions in the ecology of the water column. Phytoplankton bloom annually in spring as a result of these transitions, creating one of the major biological pulses in productivity on earth. The timing and geographical distribution of the spring bloom as well as the resulting biomass accumulation have largely been studied using the global capacity of satellite imaging. However, fine-scale variability in the taxonomic composition, spatial distribution, seasonal shifts, and ecological interactions with heterotrophic bacterioplankton has remained largely uncharacterized. The North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) conducted four meridional transects to characterize plankton ecosystems in the context of the annual bloom cycle. Using 16S rRNA gene-based community profiles we analyzed the temporal and spatial variation in plankton communities. Seasonality in phytoplankton and bacterioplankton composition was apparent throughout the water column, with changes dependent on the hydrographic origin. From winter to spring in the subtropic and subpolar subregions, phytoplankton shifted from the predominance of cyanobacteria and picoeukaryotic green algae to diverse photosynthetic eukaryotes. By autumn, the subtropics were dominated by cyanobacteria, while a diverse array of eukaryotes dominated the subpolar subregions. Bacterioplankton were also strongly influenced by geographical subregions. SAR11, the most abundant bacteria in the surface ocean, displayed higher richness in the subtropics than the subpolar subregions. SAR11 subclades were differentially distributed between the two subregions. Subclades Ia.1 and Ia.3 co-occurred in the subpolar subregion, while Ia.1 dominated the subtropics. In the subtropical subregion during the winter, the relative abundance of SAR11 subclades “II” and 1c.1 were elevated in the upper mesopelagic. In the winter, SAR202 subclades generally prevalent in the bathypelagic were also dominant members in the upper mesopelagic zones. Co-varying network analysis confirmed the large-scale geographical organization of the plankton communities and provided insights into the vertical distribution of bacterioplankton. This study represents the most comprehensive survey of microbial profiles in the western North Atlantic to date, revealing stark seasonal differences in composition and richness delimited by the biogeographical distribution of the planktonic communities.

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Section: Introductionmentioning

confidence: 99%

Seasonality of the Microbial Community Composition in the North Atlantic

et al. 2021

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“…Among PPEs, Pelagomonas calceolata was the first described member of the heterokont class Pelagophyceae 19 . It has since been identified in many oceanic regions using its 18S rRNA sequence and chloroplastic genome [20][21][22] . Several studies have demonstrated the capacity of P. calceolata to adapt to different environmental conditions.…”

Section: Introductionmentioning

confidence: 99%

Genomic adaptation of the picoeukaryote Pelagomonas calceolata to iron-poor oceans revealed by a chromosome-scale genome sequence

Guérin

Ciccarella

Flamant

et al. 2021

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Eukaryotic phytoplankton are key actors in marine ecosystems, they contribute to atmospheric CO2 sequestration and supply organic matter to the trophic network. Among them, Pelagophytes (Stramenopiles) algae are a diverse class with coastal species causative of harmful algal blooms while others are cosmopolites and abundant in open ocean ecosystems. Despite their ecological importance, only a few genomic references exist limiting our capacity to identify them and study their adaptation mechanisms in a changing environment. Here, we report the complete chromosome-scale assembled genome sequence of Pelagomonas calceolata. We identified unusual large low-GC and gene-rich regions potentially hosting centromeres. These particular genomic structures could be explained by the absence of genes necessary for an important recombination pathway in this species. We identified a large repertoire of genes involved in inorganic nitrogen sensing and uptake as well as many genes replacing iron-required proteins potentially explaining its ecological success in oligotrophic waters. Finally, based on this high-quality assembly, we evaluated P. calceolata relative abundance in all oceans using environmental Tara datasets. Our results suggest that P. calceolata is one of the most abundant eukaryote species in the oceans with a relative abundance driven by the high temperature and iron-poor conditions. Collectively, these findings bring new insights into the biology and ecology of P. calceolata and lay the foundation for the analysis of the adaptation and acclimation strategy of this picophytoplankton.

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“…Depth is the main axis of organization of both the heterotrophic and small photosyn- position depends strongly on depth and water mass (Treusch et al, 2009;Agogué et al, 2011;Choi et al, 2020). Notably, we observe that the samples from the three research cruises cluster together with differences attributable to water mass.…”

Section: Community Compositionmentioning

confidence: 66%

“…Incubations took place at 14 ∘ C in the dark in the temperature controlled room of the Pourquoi Pas?. ; Choi et al (2017Choi et al ( , 2020. PCR reactions contained 25 ng of template, 5 l of 10× buffer, 1 U of HiFi-Taq, 1.6 mM MgSO4 (Thermo Fisher) and 0.2 M of each primer.…”

Section: Respiration Ratementioning

confidence: 99%

“…Amplicons from plastids and cyanobacteria were further classified using a global plastid and cyanobacterial reference alignment and tree according to protocols outlined in Choi et al (2017). Cyanobacterial amplicons were analyzed using fine-scale cyanobacterial reference alignment and tree Sudek et al (2015), and plastid amplicons were further analyzed using multiple high-resolution alignments and trees focusing on stramenopiles and viridiplantae Choi et al (2017Choi et al ( , 2020. For the assessment of heterotrophic bacterioplankton communities, sequences (82,135,874 reads) were resolved into 49,150 amplicon sequence variants (ASVs) of 100% pairwise identity with USEARCH v10.0.240 Edgar and Flyvbjerg (2015).…”

Section: S Rrna Amplicon Analysesmentioning

confidence: 99%

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Vertical fluxes in the upper ocean

Freilich¹

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Oceanic fronts at the mesoscale and submesoscale are associated with enhanced vertical motion, which strengthens their role in global biogeochemical cycling as hotspots of primary production and subduction of carbon from the surface to the interior. Using process study models, theory, and field observations of biogeochemical tracers, this thesis improves understanding of submesoscale vertical tracer fluxes and their influence on carbon cycling. Unlike buoyancy, vertical transport of biogeochemical tracers can occur both due to the movement of isopycnals and due to motion along sloping isopycnals. We decompose the vertical velocity below the mixed layer into two components in a Lagrangian frame: vertical velocity along sloping isopycnal surfaces and the adiabatic vertical velocity of isopycnal surfaces and demonstrate that vertical motion along isopycnal surfaces is particularly important at submesoscales (1-10 km). The vertical flux of nutrient, and consequently the new production of phytoplankton depends not just on the vertical velocity but on the relative time scales of vertical transport and nutrient uptake. Vertical nutrient flux is maximum when the biological timescale of phytoplankton growth matches the vertical velocity frequency. Export of organic matter from the surface and the interior requires water parcels to cross the mixed layer base. Using Lagrangian analysis, we study the dynamics of this process and demonstrate that geostrophic and ageostrophic frontogenesis drive subduction along density surfaces across the mixed layer base. Along-front variability is an important factor in subduction. Both the physical and biological modeling studies described above are used to interpret observations from three research cruises in the Western Mediterranean. We sample intrusions of high chlorophyll and particulate organic carbon below the euphotic zone that are advected downward by 100 meters on timescales of days to weeks. We characterize the community composition in these subsurface intrusions at a lateral resolution of 1–10 km. We observe systematic changes in community composition due to the changing light environment and differential decay of the phytoplankton communities in low-light environments, along with mixing. We conclude that advective fluxes could make a contribution to carbon export in subtropical gyres that is equal to the sinking flux.

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Seasonal and Geographical Transitions in Eukaryotic Phytoplankton Community Structure in the Atlantic and Pacific Oceans

Cited by 37 publications

References 102 publications

Seasonality of the Microbial Community Composition in the North Atlantic

Seasonality of the Microbial Community Composition in the North Atlantic

Genomic adaptation of the picoeukaryote Pelagomonas calceolata to iron-poor oceans revealed by a chromosome-scale genome sequence

Vertical fluxes in the upper ocean

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