Size-fractionated biomass and primary productivity of Sargasso Sea phytoplankton

Cotti-Rausch, Bridget Elise; Lomas, Michael W.; Lachenmyer, Eric M.; Baumann, Emily G.; Richardson, Tammi L.

doi:10.1016/j.dsr.2019.103141

Cited by 9 publications

(4 citation statements)

References 58 publications

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“…Assimilation numbers (µg C µg Chla -1 h -1 ) were not impacted much by the different treatments except for a slight increase in mean microphytoplankton AN with increasing upwelling intensity (Figure 6), which can be attributed to the few very high datapoints that skewed the mean values. Microphytoplankton having generally higher AN than smaller phytoplankton is consistent with literature (Poulton et al, 2006;Cotti-Rausch et al, 2020). The absence of a strong upwelling mode or intensity effect on AN seems counterintuitive, but follows observations made by Harrison and Platt (1980) and Falkowski (1981) that showed no observable relationship between available total inorganic nitrogen and AN.…”

Section: Carbon Dynamics and Implications For Primary Production Modelssupporting

confidence: 89%

Oligotrophic Phytoplankton Community Effectively Adjusts to Artificial Upwelling Regardless of Intensity, but Differently Among Upwelling Modes

Ortíz

Arı́stegui²,

Hernández‐Hernández³

et al. 2022

Front. Mar. Sci.

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Artificial upwelling has been proposed as a means of enhancing oceanic CO2 sequestration and/or raising fishery yields through an increase in primary production in unproductive parts of the ocean. However, evidence of its efficacy, applicability and side effects is scarce. Here we present part of the results of a 37-day mesocosm study conducted in oligotrophic waters off the coast of Gran Canaria. The goal was to assess in situ the effects of artificial upwelling on the pelagic community. Upwelling was simulated via two modes: i) a singular deep-water pulse and ii) a recurring supply every 4 days; each mode at four different intensities defined by the total amount of nitrate added: approx. 1.5, 3, 5.7, and 11 µmol L-1. In this study we focus on the phytoplankton response through size-fractionated 14C primary production rates (PP), Chlorophyll a and biomass. We observed increases in PP, accumulated PP, Chlorophyll a and biomass that scaled linearly with upwelling intensity. Upwelling primarily benefitted larger phytoplankton size fractions, causing a shift from pico- and nano- to nano- and microphytoplankton. Recurring deep-water addition produced more biomass under higher upwelling intensities than a single pulse addition. It also reached significantly higher accumulated PP per unit of added nutrients and showed a stronger reduction in percentage extracellular release with increasing upwelling intensity. These results demonstrate that oligotrophic phytoplankton communities can effectively adjust to artificial upwelling regardless of upwelling intensity, but differently depending on the upwelling mode. Recurring supply of upwelled waters generated higher efficiencies in primary production and biomass build-up than a single pulse of the same volume and nutrient load.

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Section: Carbon Dynamics and Implications For Primary Production Modelssupporting

confidence: 89%

Oligotrophic Phytoplankton Community Effectively Adjusts to Artificial Upwelling Regardless of Intensity, but Differently Among Upwelling Modes

Ortíz

Arı́stegui²,

Hernández‐Hernández³

et al. 2022

Front. Mar. Sci.

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“…The pronounced seasonality observed in the Sargasso Sea implies shifts in trophic ecology and energy fluxes which likely influence biogeochemical cycles over the annual cycle (Goericke, 1998;Lomas et al, 2013). High relative abundances of mixotrophs and heterotrophs compared to autotrophs during the stratified and fall seasons indicate a complex recycling food web where small protists such as Warnowia, Telonemia, Karlodinium or Minorisa minuta and MAST and MOCH lineages prey on picophytoplankton, responsible of most of the primary production in the Sargasso Sea (Caron et al, 1999;Sanders et al, 2000;Klaveness et al, 2005;Riemann et al, 2011;Place et al, 2012;del Campo et al, 2013;Massana et al, 2014;Orsi et al, 2018;Cotti-Rausch et al, 2020). Both autotrophs and small mixo-and heterotrophs would also be preyed upon by larger mixotrophs or heterotrophs protists (Lessard and Murrell, 1998;Quevedo and Anadoń, 2001;Andersen et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…To predict future conditions, it is essential to characterize their present state (Agusti et al, 2019). In these regions, PP is dominated by the prokaryotic and eukaryotic picophytoplankton (Riemann et al, 2011;Orsi et al, 2018;Agusti et al, 2019;Cotti-Rausch et al, 2020). Much of the PP of the larger size fractions depends on mixotrophic strategies, combining autotrophy with phagotrophy on the smaller primary producers (Mitra et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

The protist community traces seasonality and mesoscale hydrographic features in the oligotrophic Sargasso Sea

et al. 2022

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Protists represent the majority of the eukaryotic diversity in the oceans. They have different functions in the marine food web, playing essential roles in the biogeochemical cycles. While the available data is rich in horizontal and temporal coverage, little is known on their vertical structuring, particularly below the photic zone. The present study applies V4 18S rDNA metabarcoding to samples collected over three years in conjunction with the BATS time-series to assess marine protist communities in the epipelagic and mesopelagic zones (0-1000 m). The protist community showed a dynamic seasonality in the epipelagic, responding to hydrographic yearly cycles. Mixotrophic lineages dominated throughout the year. However, autotrophs bloomed during the rapid transition between the winter mixing and the stratified summer, and heterotrophs had their peak at the end of summer, when the base of the thermocline reaches its deepest depth. Below the photic zone, the community, dominated by Rhizaria, is depth-stratified and relatively constant throughout the year, although they followed local hydrographic and biological features such as the oxygen minimum zone. The results suggest a dynamic partitioning of the water column, where the niche vertical position for each community changes throughout the year in the epipelagic, likely depending on nutrient availability, the mixed layer depth, and other hydrographic features. At depth, the protist community closely tracked mesoscale events (eddies), where the communities followed the hydrographic uplift, raising the deeper communities for hundreds of meters, and compressing the communities above.

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“…The pronounced seasonality observed in the Sargasso Sea implies shifts in trophic ecology and energy fluxes which likely influence biogeochemical cycles over the annual cycle. Elevated abundances of mixotrophs and heterotrophs relative to autotrophs during the stratified and fall seasons indicate a complex recycling food web where small protists such as Warnowia , Telonemia , Karlodiniumor Minorisa minuta and MAST and MOCH lineages prey on picophytoplankton, responsible of most of the primary production in the Sargasso Sea (Caron et al 1999;Cotti-Rausch et al 2020;del Campo et al 2013;Klaveness et al 2005;Massanaet al 2014;Orsi et al 2018;Place et al 2012;Riemann et al 2011;Sanders et al 2000). Both autotrophs and small mixoand heterotrophs would also be preyed upon by larger mixotrophs or heterotrophs protists (Andersen et al 2011;Evelyn & Michael 1998;Quevedo & Anadón 2001).…”

Section: Discussionmentioning

confidence: 99%

The protist community mirrors seasonality and mesoscale hydrographic features in the oligotrophic Sargasso Sea

Blanco-Bercial

Parsons

Bolaños

et al. 2022

Preprint

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Protists represent the majority of the eukaryotic diversity in the oceans. They have different functions in the marine food web, playing essential roles in the biogeochemical cycles. Meanwhile the available data is rich in horizontal and temporal coverage, little is known on their vertical structuring, particularly below the photic zone. The present study applies DNA metabarcoding to samples collected over three years in conjunction with the BATS time-series to assess marine protist communities in the epipelagic and mesopelagic zones. The protist community showed a dynamic seasonality in the epipelagic, responding to hydrographic yearly cycles. Mixotrophic lineages dominated throughout the year; however, autotrophs bloomed during the rapid transition between the winter mixing and the stratified summer, and heterotrophs had their peak at the end of summer, when the base of the thermocline reaches its deepest depth. Below the photic zone, the community, dominated by Rhizaria, is depth-stratified and relatively constant throughout the year, mirroring local hydrographic and biological features such as the oxygen minimum zone. The results suggest a dynamic partitioning of the water column, where the niche vertical position for each community changes throughout the year, likely depending on nutrient availability, the mixed layer depth, and other hydrographic features. Finally, the protist community closely followed mesoscale events (eddies), where the communities mirrored the hydrographic uplift, raising the deeper communities for hundreds of meters, and compressing the communities above.

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Size-fractionated biomass and primary productivity of Sargasso Sea phytoplankton

Cited by 9 publications

References 58 publications

Oligotrophic Phytoplankton Community Effectively Adjusts to Artificial Upwelling Regardless of Intensity, but Differently Among Upwelling Modes

Oligotrophic Phytoplankton Community Effectively Adjusts to Artificial Upwelling Regardless of Intensity, but Differently Among Upwelling Modes

The protist community traces seasonality and mesoscale hydrographic features in the oligotrophic Sargasso Sea

The protist community mirrors seasonality and mesoscale hydrographic features in the oligotrophic Sargasso Sea

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