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  • 1
    Electronic Resource
    Electronic Resource
    Climate-driven trends in contemporary ocean productivity (2006)
    [s.l.] : Nature Publishing Group
    Nature 444 (2006), S. 752-755 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Contributing roughly half of the biosphere’s net primary production (NPP), photosynthesis by oceanic phytoplankton is a vital link in the cycling of carbon between living and inorganic stocks. Each day, more than a hundred million tons of carbon in the form of CO2 are fixed ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature05317
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Controls on tropical Pacific Ocean productivity revealed through nutrient stress diagnostics (2006)
    [s.l.] : Nature Publishing Group
    Nature 442 (2006), S. 1025-1028 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In situ enrichment experiments have shown that the growth of bloom-forming diatoms in the major high-nitrate low-chlorophyll (HNLC) regions of the world's oceans is limited by the availability of iron. Yet even the largest of these manipulative experiments represents only a small fraction ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature05083
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Confirmation of iron limitation of phytoplankton photosynthesis in the equatorial Pacific Ocean (1996)
    [s.l.] : Nature Publishing Group
    Nature 383 (1996), S. 508-511 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A 64 km2 region of the eastern equatorial Pacific Ocean was enriched with ferrous sulphate to a final concentration of 2 nM iron on 29 May, followed by two 1 nM iron enrichments on 1 and 5 June 19958. The effects of iron enrichment were detected in real time by following changes in variable ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/383508a0
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Compensatory changes in Photosystem II electron turnover rates protect photosynthesis from photoinhibition (1998)
    Springer
    Photosynthesis research 58 (1998), S. 259-268 
    Details
    ISSN: 1573-5079
    Keywords: carbon fixation ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure of algae or higher plants to bright light can result in a photoinhibitory reduction in the number of functional PS II reaction centers (n) and a consequential decrease in the maximum quantum yield of photosynthesis. However, we found that light-saturated photosynthetic rates (Pmax) in natural phytoplankton assemblages sampled from the south Pacific ocean were not reduced despite photoinhibitory decreases in n of up to 52%. This striking insensitivity of Pmax to photoinhibition resulted from reciprocal increases in electron turnover ( $${1 \mathord{\left/ {\vphantom {1 {\tau _{PSII} }}} \right. \kern-\nulldelimiterspace} {\tau _{PSII} }}$$ )through the remaining functional PS II centers. Similar insensitivity of Pmax was also observed in low light adapted cultures of Thalassiosira weissflogii (a marine diatom), but not in high light adapted cells where Pmax decreased in proportion to n. This differential sensitivity to decreases in n occurred because $${1 \mathord{\left/ {\vphantom {1 {\tau _{PSII} }}} \right. \kern-\nulldelimiterspace} {\tau _{PSII} }}$$ was close to the maximum achievable rate in the high light adapted cells, whereas $${1 \mathord{\left/ {\vphantom {1 {\tau _{PSII} }}} \right. \kern-\nulldelimiterspace} {\tau _{PSII} }}$$ was initially low in the low light adapted cells and could thus increase in response to decreases in n. Our results indicate that decreases in plant productivity are not necessarily commensurate with photoinhibition, but rather will only occur if decreases in n are sufficient to maximize $${1 \mathord{\left/ {\vphantom {1 {\tau _{PSII} }}} \right. \kern-\nulldelimiterspace} {\tau _{PSII} }}$$ or incident irradiance becomes subsaturating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006138630573
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    Paper (German National Licenses)
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  • 5
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    Small phytoplankton dominate western North Atlantic biomass (2020)
    Details
    Publication Date: 2023-02-08
    Description: The North Atlantic phytoplankton spring bloom is the pinnacle in an annual cycle that is driven by physical, chemical, and biological seasonality. Despite its important contributions to the global carbon cycle, transitions in plankton community composition between the winter and spring have been scarcely examined in the North Atlantic. Phytoplankton composition in early winter was compared with latitudinal transects that captured the subsequent spring bloom climax. Amplicon sequence variants (ASVs), imaging flow cytometry, and flow-cytometry provided a synoptic view of phytoplankton diversity. Phytoplankton communities were not uniform across the sites studied, but rather mapped with apparent fidelity onto subpolar- and subtropical-influenced water masses of the North Atlantic. At most stations, cells 〈 20-µm diameter were the main contributors to phytoplankton biomass. Winter phytoplankton communities were dominated by cyanobacteria and pico-phytoeukaryotes. These transitioned to more diverse and dynamic spring communities in which pico- and nano-phytoeukaryotes, including many prasinophyte algae, dominated. Diatoms, which are often assumed to be the dominant phytoplankton in blooms, were contributors but not the major component of biomass. We show that diverse, small phytoplankton taxa are unexpectedly common in the western North Atlantic and that regional influences play a large role in modulating community transitions during the seasonal progression of blooms.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Exploring Vitamin B1 Cycling and Its Connections to the Microbial Community in the North Atlantic Ocean (2020)
    Frontiers
    Details
    Publication Date: 2023-02-08
    Description: Vitamin B1 (thiamin) is an essential coenzyme for all cells. Recent findings from experimental cell biology and genome surveys have shown that thiamin cycling by plankton is far more complex than was previously understood. Many plankton cells cannot produce thiamin (are auxotrophic) and obligately require an exogenous source of thiamin or one or more of 5 different thiamin-related compounds (TRCs). Despite this emerging evidence for the evolution among plankton of complex interactions related to thiamin, the influence of TRCs on plankton community structure and productivity are not understood. We report measurements of three dissolved TRCs 4-amino-5-aminomethyl-2-methylpyrimidine (AmMP), 5-(2-hydroxyethyl)-4-methyl-1,3-thiazole-2-carboxylic acid (cHET), and 4-methyl-5-thiazoleethanol (HET) that have never before been assayed in seawater. Here we characterize them alongside other TRCs that were measured previously [thiamin and 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP)], in depth profiles from a latitudinal transect in the north Atlantic in March 2018. TRC concentrations ranged from femptomolar to picomolar. Surface depletion relative to a maximum near the bottom of the euphotic zone and low concentrations at deeper depths were consistent features. Our observations suggest that when bacterial abundance and production are low, TRC concentrations approach a steady state where TRC production and consumption terms are balanced. Standing stocks of TRCs also appear to be positively correlated with bacterial production. However, near the period of peak biomass in the accumulation phase of a bloom we observed an inverse relationship between TRCs and bacterial production, coincident with an increased abundance of Flavobacteria that comparative genomics indicates could be vitamin B1 auxotrophs. While these observations suggest that the dissolved pool of TRCs is often at steady state, with TRC production and consumption balanced, our data suggests that bloom induced shifts in microbial community structure and activity may cause a decoupling between TRC production and consumption, leading to increased abundances of some populations of bacteria that are putatively vitamin B1 auxotrophs.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Assessing the uncertainties of model estimates of primary productivity in the tropical Pacific Ocean (2009)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 76 (2009): 113-133, doi:10.1016/j.jmarsys.2008.05.010.
    Description: Depth-integrated primary productivity (PP) estimates obtained from satellite ocean color based models (SatPPMs) and those generated from biogeochemical ocean general circulation models (BOGCMs) represent a key resource for biogeochemical and ecological studies at global as well as regional scales. Calibration and validation of these PP models are not straightforward, however, and comparative studies show large differences between model estimates. The goal of this paper is to compare PP estimates obtained from 30 different models (21 SatPPMs and 9 BOGCMs) to a tropical Pacific PP database consisting of ~1000 14C measurements spanning more than a decade (1983- 1996). Primary findings include: skill varied significantly between models, but performance was not a function of model complexity or type (i.e. SatPPM vs. BOGCM); nearly all models underestimated the observed variance of PP, specifically yielding too few low PP (〈 0.2 gC m-2d-2) values; more than half of the total root-mean-squared model-data differences associated with the satellite-based PP models might be accounted for by uncertainties in the input variables and/or the PP data; and the tropical Pacific database captures a broad scale shift from low biomass-normalized productivity in the 1980s to higher biomass-normalized productivity in the 1990s, which was not successfully captured by any of the models. This latter result suggests that interdecadal and global changes will be a significant challenge for both SatPPMs and BOGCMs. Finally, average root-mean-squared differences between in situ PP data on the equator at 140°W and PP estimates from the satellite-based productivity models were 58% lower than analogous values computed in a previous PP model comparison six years ago. The success of these types of comparison exercises is illustrated by the continual modification and improvement of the participating models and the resulting increase in model skill.
    Description: This research was supported by a grant from the National Aeronautics and Space Agency Ocean Biology and Biogeochemistry program (NNG06GA03G), as well as by numerous other grants to the various participating investigators
    Keywords: Primary production ; Modeling ; Remote sensing ; Satellite ocean color ; Statistical analysis ; Tropical Pacific Ocean (15°N to 15°S and 125°E to 95°W)
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
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  • 8
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    Regional to global assessments of phytoplankton dynamics from the SeaWiFS mission (2015)
    Elsevier
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Remote Sensing of Environment 135 (2013): 77-91, doi:10.1016/j.rse.2013.03.025.
    Description: Photosynthetic production of organic matter by microscopic oceanic phytoplankton fuels ocean ecosystems and contributes roughly half of the Earth's net primary production. For 13 years, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) mission provided the first consistent, synoptic observations of global ocean ecosystems. Changes in the surface chlorophyll concentration, the primary biological property retrieved from SeaWiFS, have traditionally been used as a metric for phytoplankton abundance and its distribution largely reflects patterns in vertical nutrient transport. On regional to global scales, chlorophyll concentrations covary with sea surface temperature (SST) because SST changes reflect light and nutrient conditions. However, the ocean may be too complex to be well characterized using a single index such as the chlorophyll concentration. A semi-analytical bio-optical algorithm is used to help interpret regional to global SeaWiFS chlorophyll observations from using three independent, well-validated ocean color data products; the chlorophyll a concentration, absorption by CDM and particulate backscattering. First, we show that observed long-term, global-scale trends in standard chlorophyll retrievals are likely compromised by coincident changes in CDM. Second, we partition the chlorophyll signal into a component due to phytoplankton biomass changes and a component caused by physiological adjustments in intracellular chlorophyll concentrations to changes in mixed layer light levels. We show that biomass changes dominate chlorophyll signals for the high latitude seas and where persistent vertical upwelling is known to occur, while physiological processes dominate chlorophyll variability over much of the tropical and subtropical oceans. The SeaWiFS data set demonstrates complexity in the interpretation of changes in regional to global phytoplankton distributions and illustrates limitations for the assessment of phytoplankton dynamics using chlorophyll retrievals alone.
    Description: The authors would like to acknowledge the NASA Ocean Biology and Biogeochemistry program for its long-term support of satellite ocean color research and the Orbital Sciences Corporation and GeoEye who were responsible for the launch, satellite integration and on-orbit management the SeaWiFS mission.
    Keywords: Ocean color ; SeaWiFS ; Phytoplankton ; Colored dissolved organic matter ; Decadal trends
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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  • 9
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    Annual cycles of ecological disturbance and recovery underlying the subarctic Atlantic spring plankton bloom (2013)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2013. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 27 (2013): 526–540, doi:10.1002/gbc.20050.
    Description: Satellite measurements allow global assessments of phytoplankton concentrations and, from observed temporal changes in biomass, direct access to net biomass accumulation rates (r). For the subarctic Atlantic basin, analysis of annual cycles in r reveals that initiation of the annual blooming phase does not occur in spring after stratification surpasses a critical threshold but rather occurs in early winter when growth conditions for phytoplankton are deteriorating. This finding has been confirmed with in situ profiling float data. The objective of the current study was to test whether satellite-based annual cycles in r are reproduced by the Biogeochemical Element Cycling–Community Climate System Model and, if so, to use the additional ecosystem properties resolved by the model to better understand factors controlling phytoplankton blooms. We find that the model gives a similar early onset time for the blooming phase, that this initiation is largely due to the physical disruption of phytoplankton-grazer interactions during mixed layer deepening, and that parallel increases in phytoplankton-specific division and loss rates during spring maintain the subtle disruption in food web equilibrium that ultimately yields the spring bloom climax. The link between winter mixing and bloom dynamics is illustrated by contrasting annual plankton cycles between regions with deeper and shallower mixing. We show that maximum water column inventories of phytoplankton vary in proportion to maximum winter mixing depth, implying that future reductions in winter mixing may dampen plankton cycles in the subarctic Atlantic. We propose that ecosystem disturbance-recovery sequences are a unifying property of global ocean plankton blooms.
    Description: This work was supported by the National Aeronautics and Space Administration, Ocean Biology and Biogeochemistry Program (grants NNX10AT70G, NNX09AK30G, NNX08AK70G, NNX07AL80G, and NNX08AP36A) and the Center for Microbial Oceanography Research and Education (C-MORE; grant EF-0424599), a National Science Foundation-supported Science and Technology Center.
    Keywords: Phytoplankton ; Bloom ; Atlantic ; Satellite ; Model ; Ecosystems
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 10
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    Reply to a comment by Stephen M. Chiswell on: “Annual cycles of ecological disturbance and recovery underlying the subarctic Atlantic spring plankton bloom” by M. J. Behrenfeld et al. (2013) (2014)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, [year]. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 27 (2013): 1294–1296, doi:10.1002/2013GB004720.
    Description: 2014-06-12
    Repository Name: Woods Hole Open Access Server
    Type: Article
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