scholarly journals Satellite-detected fluorescence reveals global physiology of ocean phytoplankton

2008 ◽  
Vol 5 (6) ◽  
pp. 4235-4270 ◽  
Author(s):  
M. J. Behrenfeld ◽  
T. K. Westberry ◽  
E. S. Boss ◽  
R. T. O'Malley ◽  
D. A. Siegel ◽  
...  
Keyword(s):  
Field Studies ◽  
Growth Conditions ◽  
Global Ocean ◽  
Physiological Status ◽  
Light Use Efficiency ◽  
Fluorescence Measurements ◽  
Ocean Productivity ◽  
Natural Iron ◽  
Use Efficiency ◽  
Ocean Ecosystem

Abstract. Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we use satellite-based fluorescence measurements to evaluate light-absorption and energy-dissipation processes influencing phytoplankton light use efficiency and demonstrate its utility as a global physiological indicator of iron-limited growth conditions. This new tool provides a path for monitoring climate-phytoplankton physiology interactions, improving descriptions of light use efficiency in ocean productivity models, evaluating nutrient-stress predictions in ocean ecosystem models, and appraising phytoplankton responses to natural iron enrichments or purposeful iron fertilizations activities.

scholarly journals Satellite-detected fluorescence reveals global physiology of ocean phytoplankton

2009 ◽  
Vol 6 (5) ◽  
pp. 779-794 ◽  
Author(s):  
M. J. Behrenfeld ◽  
T. K. Westberry ◽  
E. S. Boss ◽  
R. T. O'Malley ◽  
D. A. Siegel ◽  
...  
Keyword(s):  
Chlorophyll Concentration ◽  
Field Studies ◽  
Global Ocean ◽  
Quantum Yields ◽  
Physiological Status ◽  
Fluorescence Quantum Yields ◽  
Ocean Productivity ◽  
The Indian Ocean ◽  
Ocean Ecosystem ◽  
High Fluorescence

Abstract. Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we evaluate the physiological underpinnings of global variations in satellite-based phytoplankton chlorophyll fluorescence. The three dominant factors influencing fluorescence distributions are chlorophyll concentration, pigment packaging effects on light absorption, and light-dependent energy-quenching processes. After accounting for these three factors, resultant global distributions of quenching-corrected fluorescence quantum yields reveal a striking consistency with anticipated patterns of iron availability. High fluorescence quantum yields are typically found in low iron waters, while low quantum yields dominate regions where other environmental factors are most limiting to phytoplankton growth. Specific properties of photosynthetic membranes are discussed that provide a mechanistic view linking iron stress to satellite-detected fluorescence. Our results present satellite-based fluorescence as a valuable tool for evaluating nutrient stress predictions in ocean ecosystem models and give the first synoptic observational evidence that iron plays an important role in seasonal phytoplankton dynamics of the Indian Ocean. Satellite fluorescence may also provide a path for monitoring climate-phytoplankton physiology interactions and improving descriptions of phytoplankton light use efficiencies in ocean productivity models.

scholarly journals Potential of Photochemical Reflectance Index for Indicating Photochemistry and Light Use Efficiency in Leaves of European Beech and Norway Spruce Trees

2018 ◽  
Vol 10 (8) ◽  
pp. 1202 ◽  
Author(s):  
Daniel Kováč ◽  
Petra Veselovská ◽  
Karel Klem ◽  
Kristýna Večeřová ◽  
Alexander Ač ◽  
...  
Keyword(s):  
Norway Spruce ◽  
European Beech ◽  
Early Morning ◽  
Photochemical Quenching ◽  
Physiological Status ◽  
Photosynthetic Parameters ◽  
Light Use Efficiency ◽  
Photochemical Reflectance Index ◽  
Temperature Regimes ◽  
Use Efficiency

Hyperspectral reflectance is becoming more frequently used for measuring the functions and productivity of ecosystems. The purpose of this study was to re-evaluate the potential of the photochemical reflectance index (PRI) for evaluating physiological status of plants. This is needed because the reasons for variation in PRI and its relationships to physiological traits remain poorly understood. We examined the relationships between PRI and photosynthetic parameters in evergreen Norway spruce and deciduous European beech grown in controlled conditions during several consecutive periods of 10–12 days between which the irradiance and air temperature were changed stepwise. These regime changes induced significant changes in foliar biochemistry and physiology. The responses of PRI corresponded particularly to alterations in the actual quantum yield of photosystem II photochemistry (ΦPSII). Acclimation responses of both species led to loss of PRI sensitivity to light use efficiency (LUE). The procedure of measuring PRI at multiple irradiance-temperature conditions has been designed also for testing accuracy of ΔPRI in estimating LUE. A correction mechanism of subtracting daily measured PRI from early morning PRI has been performed to account for differences in photosynthetic pigments between irradiance-temperature regimes. Introducing ΔPRI, which provided a better estimate of non-photochemical quenching (NPQ) compared to PRI, also improved the accuracy of LUE estimation. Furthermore, ΔPRI was able to detect the effect of drought, which is poorly observable from PRI.

scholarly journals Photochemical Characterization of Greenhouse-grown Lettuce (Lactuca sativa L. ‘Green Towers’) with Applications for Supplemental Lighting Control

HortScience ◽  
2019 ◽  
Vol 54 (2) ◽  
pp. 317-322 ◽  
Author(s):  
Geoffrey Weaver ◽  
Marc W. van Iersel
Keyword(s):  
Chlorophyll Fluorescence ◽  
Lactuca Sativa ◽  
Control Strategies ◽  
Photon Flux ◽  
Production Cycle ◽  
Light Use Efficiency ◽  
Lighting Control ◽  
Fluorescence Measurements ◽  
Use Efficiency ◽  
Supplemental Lighting

Plant light use efficiency decreases as light intensity is increased, and a better understanding of crop-specific light responses can contribute to the development of more energy-efficient supplemental lighting control strategies for greenhouses. In this study, diurnal chlorophyll fluorescence monitoring was used to characterize the photochemical responses of ‘Green Towers’ lettuce (Lactuca sativa L.) to photosynthetic photon flux density (PPFD) and daily light integral (DLI) in a greenhouse during a production cycle. Plants were monitored continuously for 35 days, with chlorophyll fluorescence measurements collected once every 15 minutes. Quantum yield of photosystem II (ΦPSII) decreased exponentially with PPFD, whereas electron transport rate (ETR) increased asymptotically to 121 µmol·m–2·s–1. Daily photochemical integral (DPI) is defined as the integral of ETR over a 24-hour period; DPI increased asymptotically to 3.29 mol·m–2·d–1 with increasing DLI. No effects of plant age or prior day’s DLI and a negligible effect of PPFDs 15 or 30 minutes before measurements within days were observed. Simulations were conducted using the regression equation of ETR as a function of PPFD {ETR = 121[1 – exp(–0.00277PPFD)]} to illustrate methods of increasing photochemical light use efficiency for improved supplemental lighting control strategies. For a given DLI, DPI can be increased by providing light at lower PPFDs for a longer period of time, and can be maximized by providing light with a uniform PPFD throughout the entire photoperiod. Similarly, the DLI required to achieve a given DPI is reduced using these same methods.

Enhanced light interception and light use efficiency explain overyielding in young tree communities

2021 ◽  
Author(s):  
Laura J. Williams ◽  
Ethan E. Butler ◽  
Jeannine Cavender‐Bares ◽  
Artur Stefanski ◽  
Karen E. Rice ◽  
...  
Keyword(s):  
Light Interception ◽  
Light Use Efficiency ◽  
Young Tree ◽  
Tree Communities ◽  
Use Efficiency

scholarly journals A common garden experiment examining light use efficiency and heat sum to explain growth differences in native and exotic Pinus taeda

2018 ◽  
Vol 425 ◽  
pp. 35-44 ◽  
Author(s):  
Timothy J. Albaugh ◽  
Thomas R. Fox ◽  
Chris A. Maier ◽  
Otávio C. Campoe ◽  
Rafael A. Rubilar ◽  
...  
Keyword(s):  
Pinus Taeda ◽  
Common Garden ◽  
Light Use Efficiency ◽  
Common Garden Experiment ◽  
Use Efficiency ◽  
Growth Differences

scholarly journals MAREDAT: towards a World Ocean Atlas of MARine Ecosystem DATa

2012 ◽  
Vol 5 (2) ◽  
pp. 1077-1106 ◽  
Author(s):  
E. T. Buitenhuis ◽  
M. Vogt ◽  
R. Moriarty ◽  
N. Bednaršek ◽  
S. C. Doney ◽  
...  
Keyword(s):  
Marine Ecosystem ◽  
World Ocean ◽  
Zooplankton Biomass ◽  
Global Ocean ◽  
Special Issue ◽  
Biomass Distribution ◽  
Phytoplankton Pigment ◽  
Autotrophic Biomass ◽  
Ocean Ecosystem ◽  
World Ocean Atlas

Abstract. We present a summary of biomass data for 11 Plankton Functional Types (PFTs) plus phytoplankton pigment data, compiled as part of the MARine Ecosystem biomass DATa (MAREDAT) initiative. The goal of the MAREDAT initiative is to provide global gridded data products with coverage of all biological components of the global ocean ecosystem. This special issue is the first step towards achieving this. The PFTs presented here include picophytoplankton, diazotrophs, coccolithophores, Phaeocystis, diatoms, picoheterotrophs, microzooplankton, foraminifers, mesozooplankton, pteropods and macrozooplankton. All variables have been gridded onto a World Ocean Atlas (WOA) grid (1° × 1° × 33 vertical levels × monthly climatologies). The data show that (1) the global total heterotrophic biomass (2.0–6.4 Pg C) is at least as high as the total autotrophic biomass (0.5–2.6 Pg C excluding nanophytoplankton and autotrophic dinoflagellates), (2) the biomass of zooplankton calcifiers (0.9–2.3 Pg C) is substantially higher than that of coccolithophores (0.01–0.14 Pg C), (3) patchiness of biomass distribution increases with organism size, and (4) although zooplankton biomass measurements below 200 m are rare, the limited measurements available suggest that Bacteria and Archaea are not the only heterotrophs in the deep sea. More data will be needed to characterize ocean ecosystem functioning and associated biogeochemistry in the Southern Hemisphere and below 200 m. Microzooplankton database: doi:10.1594/PANGAEA.779970.

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