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Author

Zbigniew Kolber

Bio: Zbigniew Kolber is an academic researcher from Monterey Bay Aquarium Research Institute. The author has contributed to research in topics: Photosynthesis & Chlorophyll fluorescence. The author has an hindex of 42, co-authored 76 publications receiving 10743 citations. Previous affiliations of Zbigniew Kolber include Rutgers University & University of California, Santa Cruz.


Papers
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Journal ArticleDOI
08 Sep 1994-Nature
TL;DR: Findings indicate that iron limitation can control rates of phytoplankton productivity and biomass in the ocean.
Abstract: The idea that iron might limit phytoplankton growth in large regions of the ocean has been tested by enriching an area of 64 km2 in the open equatorial Pacific Ocean with iron This resulted in a doubling of plant biomass, a threefold increase in chlorophyll and a fourfold increase in plant production Similar increases were found in a chlorophyll-rich plume down-stream of the Galapagos Islands, which was naturally enriched in iron These findings indicate that iron limitation can control rates of phytoplankton productivity and biomass in the ocean

1,346 citations

Journal ArticleDOI
TL;DR: Fast repetition rate (FRR) fluorescence as mentioned in this paper applies a sequence of subsaturating excitation pulses ('flashlets') at microsecond intervals to induce fluorescence transients, which can be extremely flexible and allow the generation of both single-turnover (ST) and multiple-transover (MT) flashes.

763 citations

01 Jan 1998
TL;DR: The simultaneous measurements of sigmaPS II, p, and the kinetics of Q-A reoxidation, which can be derived only from a combination of ST and MT flash fluorescence transients, permits robust characterization of the processes of photosynthetic energy-conversion.
Abstract: We present a methodology, called fast repetition rate (FRR) fluorescence, that measures the functional absorption crosssection (cPS II) of Photosystem II (PS II), energy transfer between PS II units (p), photochemical and nonphotochemical quenching of chlorophyll fluorescence, and the kinetics of electron transfer on the acceptor side of PS II. The FRR fluorescence technique applies a sequence of subsaturating excitation pulses (‘flashlets’) at microsecond intervals to induce fluorescence transients. This approach is extremely flexible and allows the generation of both single-turnover (ST) and multiple-turnover (MT) flashes. Using a combination of ST and MT flashes, we investigated the effect of excitation protocols on the measured fluorescence parameters. The maximum fluorescence yield induced by an ST flash applied shortly (10 W st o 5 ms) following an MT flash increased to a level comparable to that of an MT flash, while the functional absorption crosssection decreased by about 40%. We interpret this phenomenon as evidence that an MT flash induces an increase in the fluorescence-rate constant, concomitant with a decrease in the photosynthetic-rate constant in PS II reaction centers. The simultaneous measurements of cPS II, p, and the kinetics of Q 3 reoxidation, which can be derived only from a combination of ST and MT flash fluorescence transients, permits robust characterization of the processes of photosynthetic energyconversion. fl 1998 Elsevier Science B.V. All rights reserved.

703 citations

Journal ArticleDOI
TL;DR: In this paper, a pump-and-probe fluorescence technique was used to measure the change in the quantum yield of fluorescence induced by the strong pump flash, which was then used to derive the absolute absorption cross sections for photosystem 2 and the maximum rate of photosynthetic electron transport at light saturation.
Abstract: We describe the theory and practice of estimating photosynthetic rates from light-stimulated changes in the quantum yield of chlorophyll fluorescence. By means of a pump-and-probe fluorescence technique, where weak probe flashes are used to measure the change in the quantum yield of fluorescence induced by the strong pump flash, it is possible to derive the absolute absorption cross sections for photosystem 2, the quantum yield for photochemistry, and the maximum rate of photosynthetic electron transport at light saturation. In conjunction with a semiempirical biophysical model of photosynthesis, these parameters can bc used to calculate the instantaneous rate of gross photosynthesis in situ under ambient irradiance. A profiling pump-and-probe fluorometer was constructed and interfaced with a CTD, and vertical profiles of variable fluorescence were obtained on four cruises in the northwest Atlantic Ocean. The derived photosynthetic rates were compared with concurrent estimates of production based on radiocarbon uptake. The correlation coefficient between the two estimates of primary production, normalized to Chl a, was 0.86; linear regression analysis yielded a slope of 1.06. There is a 3-4-fold range in the maximum change in the quantum yields of photochemistry and absorption cross-sections in natural phytoplankton communities. Uncertainties in the pump-and-probe-derived estimates of photosynthesis arc primarily due to temporal mismatches between instantaneous and time-integrated measures of production and in biological variability in the ratio of the number of PS2 reaction centers to total Chl a. Almost all measurements of phytoplankton photosynthesis in situ are based on the timedependent incorporation of radiocarbon into particulate matter or on changes in concentration of dissolved oxygen in the bulk fluid.

611 citations

Journal ArticleDOI
04 Jul 1991-Nature
TL;DR: In this paper, a pump-and-probe fluorimeter was used to evaluate the effect of cyclonic eddies on phytoplankton production in the subtropical Pacific.
Abstract: Eddy pumping is considered to explain the disparity between geochemical estimates and biological measurements of exported production. Episodic nutrient injections from the ocean into the photic zone can be generated by eddy pumping, which biological measurements cannot sample accurately. The enhancement of production is studied with respect to a cyclonic eddy in the subtropical Pacific. A pump-and-probe fluorimeter generates continuous vertical profiles of primary productivity from which the contributions of photochemical and nonphotochemical processes to fluorescence are derived. A significant correlation is observed between the fluorescence measurements and radiocarbon measurements. The results indicate that eddy pumping has an important effect on phytoplankton production and that this production is near the maximum relative specific growth rates. Based on the production enhancement observed in this case, eddy pumping increases total primary production by only 20 percent and does not account for all enhancement.

573 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the authors compared the natural and anthropogenic controls on the conversion of unreactive N2 to more reactive forms of nitrogen (Nr) and found that human activities increasingly dominate the N budget at the global and at most regional scales, and the terrestrial and open ocean N budgets are essentially dis-connected.
Abstract: This paper contrasts the natural and anthropogenic controls on the conversion of unreactive N2 to more reactive forms of nitrogen (Nr). A variety of data sets are used to construct global N budgets for 1860 and the early 1990s and to make projections for the global N budget in 2050. Regional N budgets for Asia, North America, and other major regions for the early 1990s, as well as the marine N budget, are presented to highlight the dominant fluxes of nitrogen in each region. Important findings are that human activities increasingly dominate the N budget at the global and at most regional scales, the terrestrial and open ocean N budgets are essentially dis- connected, and the fixed forms of N are accumulating in most environmental reservoirs. The largest uncertainties in our understanding of the N budget at most scales are the rates of natural biological nitrogen fixation, the amount of Nr storage in most environmental reservoirs, and the production rates of N2 by denitrification.

4,555 citations

Journal ArticleDOI
29 Sep 2005-Nature
TL;DR: 13 models of the ocean–carbon cycle are used to assess calcium carbonate saturation under the IS92a ‘business-as-usual’ scenario for future emissions of anthropogenic carbon dioxide and indicate that conditions detrimental to high-latitude ecosystems could develop within decades, not centuries as suggested previously.
Abstract: Today's surface ocean is saturated with respect to calcium carbonate, but increasing atmospheric carbon dioxide concentrations are reducing ocean pH and carbonate ion concentrations, and thus the level of calcium carbonate saturation. Experimental evidence suggests that if these trends continue, key marine organisms—such as corals and some plankton—will have difficulty maintaining their external calcium carbonate skeletons. Here we use 13 models of the ocean–carbon cycle to assess calcium carbonate saturation under the IS92a 'business-as-usual' scenario for future emissions of anthropogenic carbon dioxide. In our projections, Southern Ocean surface waters will begin to become undersaturated with respect to aragonite, a metastable form of calcium carbonate, by the year 2050. By 2100, this undersaturation could extend throughout the entire Southern Ocean and into the subarctic Pacific Ocean. When live pteropods were exposed to our predicted level of undersaturation during a two-day shipboard experiment, their aragonite shells showed notable dissolution. Our findings indicate that conditions detrimental to high-latitude ecosystems could develop within decades, not centuries as suggested previously.

4,244 citations

Journal ArticleDOI
TL;DR: In this paper, a light-dependent, depth-resolved model for carbon fixation (VGPM) was developed to understand the critical variables required for accurate assessment of daily depth-integrated phytoplankton carbon fixation from measurements of sea surface pigment concentrations (Csat)(Csat).
Abstract: We assembled a dataset of 14C-based productivity measurements to understand the critical variables required for accurate assessment of daily depth-integrated phytoplankton carbon fixation (PP(PPeu)u) from measurements of sea surface pigment concentrations (Csat)(Csat). From this dataset, we developed a light-dependent, depth-resolved model for carbon fixation (VGPM) that partitions environmental factors affecting primary production into those that influence the relative vertical distribution of primary production (Pz)z) and those that control the optimal assimilation efficiency of the productivity profile (P(PBopt). The VGPM accounted for 79% of the observed variability in Pz and 86% of the variability in PPeu by using measured values of PBopt. Our results indicate that the accuracy of productivity algorithms in estimating PPeu is dependent primarily upon the ability to accurately represent variability in Pbopt. We developed a temperature-dependent Pbopt model that was used in conjunction with monthly climatological images of Csat sea surface temperature, and cloud-corrected estimates of surface irradiance to calculate a global annual phytoplankton carbon fixation (PPannu) rate of 43.5 Pg C yr‒1. The geographical distribution of PPannu was distinctly different than results from previous models. Our results illustrate the importance of focusing Pbopt model development on temporal and spatial, rather than the vertical, variability.

2,471 citations

Journal ArticleDOI
01 Jan 1992
TL;DR: The Xanthophyll cycle and thermal energy dissipation were investigated in this paper. But the results of these experiments were limited to the case of light-capturing systems, where active oxygen was not formed in the Photochemical Apparatus.
Abstract: PHOTO PROTECTION 604 Prevention oj Excessive Light Absorption... 604 Removal of Excess Excitation Energy Directly within the Light-Capturing System ......... ...... . . ..... ..... . .... . ..... ...... .... . .. . .. . . ..... . . . ... ... . 604 Removal oj Active Oxygen Formed in the Photochemical Apparatus ........ . . .. . . . . . . 605 INACTIV A TIONiTURNOVER OF PS II 606 THE XANTHOPHYLL CYCLE AND THERMAL ENERGY DISSIPATION: A PHOTOPROTECTIVE RESPONSE 608 Characteristics oj the Xanthophyll Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 608 Association Among the De-epoxidized State oj the Xanthophyll Cycle, Thermal Energy Dissipation. and Photoprotection .. .. . . . .. . . ...... .. .. ... ... 609 Operation of the Xanthophyll Cycle in the Field . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .... . . . .. . . . . 611 CONCLUSIONS 618

2,388 citations

Journal ArticleDOI
23 May 2008-Science
TL;DR: Virtually all nonequilibrium electron transfers on Earth are driven by a set of nanobiological machines composed largely of multimeric protein complexes associated with a small number of prosthetic groups.
Abstract: Virtually all nonequilibrium electron transfers on Earth are driven by a set of nanobiological machines composed largely of multimeric protein complexes associated with a small number of prosthetic groups. These machines evolved exclusively in microbes early in our planet's history yet, despite their antiquity, are highly conserved. Hence, although there is enormous genetic diversity in nature, there remains a relatively stable set of core genes coding for the major redox reactions essential for life and biogeochemical cycles. These genes created and coevolved with biogeochemical cycles and were passed from microbe to microbe primarily by horizontal gene transfer. A major challenge in the coming decades is to understand how these machines evolved, how they work, and the processes that control their activity on both molecular and planetary scales.

2,345 citations