Ecology of Marine Phytoplankton

Geider, Richard J.; Moore, C. M.; Suggett, DJ

doi:10.1007/978-1-4614-7612-2_23-1

Cited by 3 publications

(2 citation statements)

References 27 publications

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“…The techniques's use of pigments estimates with algorithms for PFTs should be used with caution because pigment ratios can vary with phytoplankton species composition, light history, and acclimation to temperature and nutrients (Moisan and Mitchell, 1999;Louanchi and Najjar, 2001;Woodward and Rees, 2001;McGillicuddy et al, 2003;Geider et al, 2014). In this paper, PFTs are reported in terms of pigments to Chl MOD SAT ratios in order to be comparable with past HPLC studies and to reduce possible pigment estimate bias errors (Roy et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

Satellite Observations of Phytoplankton Functional Type Spatial Distributions, Phenology, Diversity, and Ecotones

et al. 2017

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Phytoplankton functional diversity plays a key role in structuring the ocean carbon cycle and can be estimated using measurements of phytoplankton functional type (PFT) groupings. Concentrations of 18 phytoplankton pigments were calculated using a linear matrix inversion algorithm, with an average r 2 value of 0.70 for all pigments with p-values below the statistical threshold of 0.05. The inversion algorithm was then used with a chlorophyll-based absorption spectra model and Moderate Resolution Imaging Spectroradiometer (MODIS-Aqua) chlorophyll observations to calculate phytoplankton pigment concentrations in an area of the Atlantic Ocean off the United States east coast. Pigment distributions were analyzed to assess the distribution of PFTs. Five unique PFTs were found and delineated into three distinct offshore, transition, and open ocean groups. Group 1 (Diatoms) had highest abundance along the coast. Group 2 (prymnesiophytes, prokaryotes, and green algae) was a year-round stable offshore community that extended at reduced levels into the coast. Group 3 (dinoflagellates) dominated offshore between the Groups 1 and 2. Phytoplankton communities were delineated into coastal and offshore populations, with Group 2 having a dampened seasonal cycle, relative to the coastal populations. Shannon Diversity Indices (H) for the PFTs showed both spatial and temporal variability and had a clear non-linear relationship with chlorophyll. Diversity levels varied seasonally with changes in chlorophyll a levels. Peak PFT H was observed on the shelf where frontal features dominate, with diversity levels declining nearshore and offshore. This region marks an ecotone for phytoplankton in the study domain, and is associated with the coastal-side boundary of dinoflagellate dominance. Highest levels of diversity were observed in the tidally well-mixed regions of the Gulf of Maine and along a band that ran along the shelf region of the study area that was narrowest in the summer periods and broadened during the winter. These peak diversity zones were associated with moderate levels (∼0.8 mg m −3 ) of chlorophyll a. While the sign in the linear trends in chlorophyll between 2002 and 2016 varied depending on the region, the trends in the PFT H values were nearly all negative due to the non-linear relationship between chlorophyll levels and H.

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Section: Discussionmentioning

confidence: 99%

Satellite Observations of Phytoplankton Functional Type Spatial Distributions, Phenology, Diversity, and Ecotones

et al. 2017

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“…Marine phytoplankton accounts for about half of the world's net primary production of biogenic carbon (Geider et al, ). The export of biogenic particles from the euphotic zone to the deep plays a crucial role in the marine carbon cycle.…”

Section: Introductionmentioning

confidence: 99%

²³⁴Th‐Based Carbon Export Flux Along the Indian GEOTRACES GI02 Section in the Arabian Sea and the Indian Ocean

Anand

Rengarajan

Sarma

2018

Global Biogeochemical Cycles

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234Th (t1/2 = 24.1 d), present in seawater, is a naturally occurring particle‐reactive radionuclide formed through the radioactive decay of its parent, 238U (t1/2 = 4.47 × 109 years). The 234Th:238U disequilibrium is exploited to quantify fluxes of elements moving out of the euphotic zone by attaching on to sinking particles. Under the Indian GEOTRACES programme, high‐resolution sampling in the upper 300 m depth was carried out at 11 stations in the Arabian Sea and the Indian Ocean during April–May 2014 from 17°N to 16°S along 65°E transect to estimate the 234Th‐based particulate organic carbon (POC) export flux from the upper ocean. Average 234Th fluxes integrated to 100 m depth were 2,612 and 1,968 dpm m−2 d−1 for the Arabian Sea and the Indian Ocean, respectively. The estimated POC export fluxes ranged from negligible to 9.0 mmol m−2 d−1, and the 234Th‐based POC export efficiencies were <2 to 5%. For the same season, the Arabian Sea and the Bay of Bengal showed highly contrasting carbon export trends (mean: 4.0 and 0.8 mmol C m−2 d−1, respectively). The modeled POC export fluxes from in situ and satellite‐derived primary production are higher than the 234Th‐based values for the Laws and Dunne models and are comparable for the Henson model. The modeled POC fluxes that depend on surface temperature and primary production could be further refined for the seasonal cycle in biological productivity and associated differences in trophic structure, grazing intensity, recycling efficiency, high bacterial activity, and associated dissolved organic carbon (DOC) export.

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Growth dynamics and transcriptional responses of a Red SeaProchlorococcus strain to varying temperatures

Labban

Shibl

Calleja

et al. 2023

Environmental Microbiology

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Prochlorococcus play a crucial role in the ocean's biogeochemical cycling, but it remains controversial how they will respond to global warming. Here we assessed the response to temperature (22–30°C) of the growth dynamics and gene expression profiles of a Red Sea Prochlorococcus strain (RSP50) in a non‐axenic culture. Both the specific growth rate (0.55–0.80 day−1) and cell size (0.04–0.07 μm3) of Prochlorococcus increased significantly with temperature. The primary production released extracellularly ranged from 20% to 34%, with humic‐like fluorescent compounds increasing up to fivefold as Prochlorococcus reached its maximum abundance. At 30°C, genes involved in carbon fixation such as CsoS2 and CsoS3 and photosynthetic electron transport including PTOX were downregulated, suggesting a cellular homeostasis and energy saving mechanism response. In contrast, PTOX was found upregulated at 22°C and 24°C. Similar results were found for transaldolase, related to carbon metabolism, and citrate synthase, an important enzyme in the TCA cycle. Our data suggest that in spite of the currently warm temperatures of the Red Sea, Prochlorococcus can modulate its gene expression profiles to permit growth at temperatures lower than its optimum temperature (28°C) but is unable to cope with temperatures exceeding 30°C.

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Ecology of Marine Phytoplankton

Cited by 3 publications

References 27 publications

Satellite Observations of Phytoplankton Functional Type Spatial Distributions, Phenology, Diversity, and Ecotones

Satellite Observations of Phytoplankton Functional Type Spatial Distributions, Phenology, Diversity, and Ecotones

²³⁴Th‐Based Carbon Export Flux Along the Indian GEOTRACES GI02 Section in the Arabian Sea and the Indian Ocean

Growth dynamics and transcriptional responses of a Red SeaProchlorococcus strain to varying temperatures

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Ecology of Marine Phytoplankton

Cited by 3 publications

References 27 publications

Satellite Observations of Phytoplankton Functional Type Spatial Distributions, Phenology, Diversity, and Ecotones

Satellite Observations of Phytoplankton Functional Type Spatial Distributions, Phenology, Diversity, and Ecotones

234Th‐Based Carbon Export Flux Along the Indian GEOTRACES GI02 Section in the Arabian Sea and the Indian Ocean

Growth dynamics and transcriptional responses of a Red SeaProchlorococcus strain to varying temperatures

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²³⁴Th‐Based Carbon Export Flux Along the Indian GEOTRACES GI02 Section in the Arabian Sea and the Indian Ocean