1
|
Shimakawa G, Matsuda Y. Extra O 2 evolution reveals an O 2-independent alternative electron sink in photosynthesis of marine diatoms. PHOTOSYNTHESIS RESEARCH 2024; 159:61-68. [PMID: 38316719 DOI: 10.1007/s11120-023-01073-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 12/27/2023] [Indexed: 02/07/2024]
Abstract
Following the principle of oxygenic photosynthesis, electron transport in the thylakoid membranes (i.e., light reaction) generates ATP and NADPH from light energy, which is subsequently utilized for CO2 fixation in the Calvin-Benson-Bassham cycle (i.e., dark reaction). However, light and dark reactions could discord when an alternative electron flow occurs with a rate comparable to the linear electron flow. Here, we quantitatively monitored O2 and total dissolved inorganic carbon (DIC) during photosynthesis in the pennate diatom Phaeodactylum tricornutum, and found that evolved O2 was larger than the consumption of DIC, which was consistent with 14CO2 measurements in literature. In our measurements, the stoichiometry of O2 evolution to DIC consumption was always around 1.5 during photosynthesis at different DIC concentrations. The same stoichiometry was observed in the cells grown under different CO2 concentrations and nitrogen sources except for the nitrogen-starved cells showing O2 evolution 2.5 times larger than DIC consumption. An inhibitor to nitrogen assimilation did not affect the extra O2 evolution. Further, the same physiological phenomenon was observed in the centric diatom Thalassiosira pseudonana. Based on the present dataset, we propose that the marine diatoms possess the metabolic pathway(s) functioning as the O2-independent electron sink under steady state photosynthesis that reaches nearly half of electron flux of the Calvin-Benson-Bassham cycle.
Collapse
Affiliation(s)
- Ginga Shimakawa
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo, 669-1330, Japan.
| | - Yusuke Matsuda
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei Gakuin University, 1 Gakuen Uegahara, Sanda, Hyogo, 669-1330, Japan
| |
Collapse
|
2
|
Rehder L, Rost B, Rokitta SD. Abrupt and acclimation responses to changing temperature elicit divergent physiological effects in the diatom Phaeodactylum tricornutum. THE NEW PHYTOLOGIST 2023. [PMID: 37247339 DOI: 10.1111/nph.18982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 04/14/2023] [Indexed: 05/31/2023]
Abstract
Growth rates and other biomass traits of phytoplankton are strongly affected by temperature. We hypothesized that resulting phenotypes originate from deviating temperature sensitivities of underlying physiological processes. We used membrane-inlet mass spectrometry to assess photosynthetic and respiratory O2 and CO2 fluxes in response to abrupt temperature changes as well as after acclimation periods in the diatom Phaeodactylum tricornutum. Abrupt temperature changes caused immediate over- or undershoots in most physiological processes, that is, photosynthetic oxygen release ( PS O 2 $$ {\mathrm{PS}}_{{\mathrm{O}}_2} $$ ), photosynthetic carbon uptake ( PS CO 2 $$ {\mathrm{PS}}_{{\mathrm{CO}}_2} $$ ), and respiratory oxygen release ( R O 2 $$ {\mathrm{R}}_{{\mathrm{O}}_2} $$ ). Over acclimation timescales, cells were, however, able to re-adjust their physiology and revert to phenotypic 'sweet spots'. Respiratory CO2 release ( R CO 2 $$ {\mathrm{R}}_{{\mathrm{CO}}_2} $$ ) was generally inhibited under high temperature and stimulated under low-temperature settings, on abrupt as well as acclimation timescales. Such behavior may help mitochondria to stabilize plastidial ATP : NADPH ratios and thus maximize photosynthetic carbon assimilation.
Collapse
Affiliation(s)
- Linda Rehder
- Alfred-Wegener-Institute, Helmholtz-Centre for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, 27570, Germany
- FB2 Biology/Chemistry, University of Bremen, Leobener Straße, Bremen, 28359, Germany
| | - Björn Rost
- Alfred-Wegener-Institute, Helmholtz-Centre for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, 27570, Germany
- FB2 Biology/Chemistry, University of Bremen, Leobener Straße, Bremen, 28359, Germany
| | - Sebastian D Rokitta
- Alfred-Wegener-Institute, Helmholtz-Centre for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, 27570, Germany
| |
Collapse
|
3
|
Laws EA, McClellan SA. Interactive effects of CO 2 , temperature, irradiance, and nutrient limitation on the growth and physiology of the marine cyanobacterium Synechococcus (Cyanophyceae). JOURNAL OF PHYCOLOGY 2022; 58:703-718. [PMID: 35830205 PMCID: PMC9805005 DOI: 10.1111/jpy.13278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 06/24/2022] [Indexed: 06/15/2023]
Abstract
The marine cyanobacterium Synechococcus elongatus was grown in a continuous culture system to study the interactive effects of temperature, irradiance, nutrient limitation, and the partial pressure of CO2 (pCO2) on its growth and physiological characteristics. Cells were grown on a 14:10 h light:dark cycle at all combinations of low and high irradiance (50 and 300 μmol photons ⋅ m-2 ⋅ s-1 , respectively), low and high pCO2 (400 and 1000 ppmv, respectively), nutrient limitation (nitrate-limited and nutrient-replete conditions), and temperatures of 20-45°C in 5°C increments. The maximum growth rate was ~4.5 · d-1 at 30-35°C. Under nutrient-replete conditions, growth rates at most temperatures and irradiances were about 8% slower at a pCO2 of 1000 ppmv versus 400 ppmv. The single exception was 45°C and high irradiance. Under those conditions, growth rates were ~45% higher at 1000 ppmv. Cellular carbon:nitrogen ratios were independent of temperature at a fixed relative growth rate but higher at high irradiance than at low irradiance. Initial slopes of photosynthesis-irradiance curves were higher at all temperatures under nutrient-replete versus nitrate-limited conditions; they were similar at all temperatures under high and low irradiance, except at 20°C, when they were suppressed at high irradiance. A model of phytoplankton growth in which cellular carbon was allocated to structure, storage, or the light or dark reactions of photosynthesis accounted for the general patterns of cell composition and growth rate. Allocation of carbon to the light reactions of photosynthesis was consistently higher at low versus high light and under nutrient-replete versus nitrate-limited conditions.
Collapse
Affiliation(s)
- Edward A. Laws
- Department of Environmental SciencesLouisiana State UniversityBaton RougeLouisiana70803USA
| | - S. Alex McClellan
- Department of Environmental SciencesLouisiana State UniversityBaton RougeLouisiana70803USA
| |
Collapse
|
4
|
Millette N, Kelble C, Smith I, Montenero K, Harvey E. Spatial variability of microzooplankton grazing on phytoplankton in coastal southern Florida, USA. PeerJ 2022; 10:e13291. [PMID: 35497184 PMCID: PMC9048640 DOI: 10.7717/peerj.13291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 03/28/2022] [Indexed: 01/13/2023] Open
Abstract
Microzooplankton are considered the primary consumers of phytoplankton in marine environments. Microzooplankton grazing rates on phytoplankton have been studied across the globe, but there are still large regions of the ocean that are understudied, such as sub-tropical coastal oceans. One of these regions is the coastal area around south Florida, USA. We measured microzooplankton grazing rates in two distinct environments around south Florida; the oligotrophic Florida Keys and the mesotrophic outflow from the Everglades. For 2-years from January 2018 to January 2020, we set up 55 dilution and light-dark bottle experiments at five stations to estimate the microzooplankton community grazing rate, instantaneous phytoplankton growth rate, and primary production. Our results suggest that microzooplankton are consuming a higher proportion of the primary production near the Everglades outflow compared to the Florida Keys. We also found that changes in phytoplankton growth rates are disconnected from changes in the microzooplankton grazing rates in the Florida Keys. Overall, the data from the Everglades outflow is what would be expected based on global patterns, but factors other than microzooplankton grazing are more important in controlling phytoplankton biomass in the Florida Keys.
Collapse
Affiliation(s)
- Nicole Millette
- William & Mary, Virginia Institute of Marine Science, Gloucester Point, VA, United States
| | - Christopher Kelble
- Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration, Miami, FL, United States
| | - Ian Smith
- Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration, Miami, FL, United States,University of Miami, Cooperative Institute for Marine and Atmospheric Studies, Miami, FL, United States
| | - Kelly Montenero
- Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration, Miami, FL, United States,University of Miami, Cooperative Institute for Marine and Atmospheric Studies, Miami, FL, United States
| | - Elizabeth Harvey
- Department of Biological Sciences, University of New Hampshire, Durham, NH, United States
| |
Collapse
|
5
|
Gorbunov MY, Falkowski PG. Using Chlorophyll Fluorescence to Determine the Fate of Photons Absorbed by Phytoplankton in the World's Oceans. ANNUAL REVIEW OF MARINE SCIENCE 2022; 14:213-238. [PMID: 34460315 DOI: 10.1146/annurev-marine-032621-122346] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Approximately 45% of the photosynthetically fixed carbon on Earth occurs in the oceans in phytoplankton, which account for less than 1% of the world's photosynthetic biomass. This amazing empirical observation implies a very high photosynthetic energy conversion efficiency, but how efficiently is the solar energy actually used? The photon energy budget of photosynthesis can be divided into three terms: the quantum yields of photochemistry, fluorescence, and heat. Measuring two of these three processes closes the energy budget. The development of ultrasensitive, seagoing chlorophyll variable fluorescence and picosecond fluorescence lifetime instruments has allowed independent closure on the first two terms. With this closure, we can understand how phytoplankton respond to nutrient supplies on timescales of hours to months and, over longer timescales, to changes in climate.
Collapse
Affiliation(s)
- Maxim Y Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA; ,
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA; ,
| |
Collapse
|
6
|
Rearte T, Rodriguez N, Sabatté F, Fabrizio de Iorio A. Unicellular microalgae vs. filamentous algae for wastewater treatment and nutrient recovery. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102442] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
|
7
|
Spatial Patterns of Macromolecular Composition of Phytoplankton in the Arctic Ocean. WATER 2021. [DOI: 10.3390/w13182495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The macromolecular concentrations and compositions of phytoplankton are crucial for the growth or nutritional structure of higher trophic levels through the food web in the ecosystem. To understand variations in macromolecular contents of phytoplankton, we investigated the macromolecular components of phytoplankton and analyzed their spatial pattern on the Chukchi Shelf and the Canada Basin. The carbohydrate (CHO) concentrations on the Chukchi Shelf and the Canada Basin were 50.4–480.8 μg L−1 and 35.2–90.1 μg L−1, whereas the lipids (LIP) concentrations were 23.7–330.5 μg L−1 and 11.7–65.6 μg L−1, respectively. The protein (PRT) concentrations were 25.3–258.5 μg L−1 on the Chukchi Shelf and 2.4–35.1 μg L−1 in the Canada Basin. CHO were the predominant macromolecules, accounting for 42.6% on the Chukchi Shelf and 60.5% in the Canada Basin. LIP and PRT contributed to 29.7% and 27.7% of total macromolecular composition on the Chukchi Shelf and 30.8% and 8.7% in the Canada Basin, respectively. Low PRT concentration and composition in the Canada Basin might be a result from the severe nutrient-deficient conditions during phytoplankton growth. The calculated food material concentrations were 307.8 and 98.9 μg L−1, and the average calorie contents of phytoplankton were 1.9 and 0.6 kcal m−3 for the Chukchi Shelf and the Canada Basin, respectively, which indicates the phytoplankton on the Chukchi Shelf could provide the large quantity of food material and high calories to the higher trophic levels. Overall, our results highlight that the biochemical compositions of phytoplankton are considerably different in the regions of the Arctic Ocean. More studies on the changes in the biochemical compositions of phytoplankton are still required under future environmental changes.
Collapse
|
8
|
Moeller HV, Hsu V, Lepori-Bui M, Mesrop LY, Chinn C, Johnson MD. Prey type constrains growth and photosynthetic capacity of the kleptoplastidic ciliate Mesodinium chamaeleon (Ciliophora). JOURNAL OF PHYCOLOGY 2021; 57:916-930. [PMID: 33454988 DOI: 10.1111/jpy.13131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 12/18/2020] [Accepted: 12/21/2020] [Indexed: 06/12/2023]
Abstract
Kleptoplastidic, or chloroplast-stealing, lineages offer insight into the process of acquiring photosynthesis. By quantifying the ability of these organisms to retain and use photosynthetic machinery from their prey, we can understand how intermediaries on the endosymbiosis pathway might have evolved regulatory and maintenance mechanisms. Here, we focus on a mixotrophic kleptoplastidic ciliate, Mesodinium chamaeleon, noteworthy for its ability to retain functional chloroplasts from at least half a dozen cryptophyte algal genera. We contrasted the performance of kleptoplastids from blue-green and red cryptophyte prey as a function of light level and feeding history. Our experiments showed that starved M. chamaeleon cells are able to maintain photosynthetic function for at least 2 weeks and that M. chamaeleon containing red plastids lost chlorophyll and electron transport capacity faster than those containing blue-green plastids. However, likely due to increased pigment content and photosynthetic rates in red plastids, M. chamaeleon had higher growth rates and more prolonged growth when feeding on red cryptophytes. For example, M. chamaeleon grew rapidly and extensively when fed the blue-green cryptophyte Chroomonas mesostigmatica, but this growth appeared to hinge on high levels of feeding supporting photosynthetic activity. In contrast, even starved M. chamaeleon containing red plastids from Rhodomonas salina could achieve high photosynthetic rates and extensive growth. Our findings show that plastid origin impacts the maintenance and magnitude of photosynthetic activity, though whether this is due to variation in ciliate control or gradual loss of plastid function in ingested prey cells remains unknown.
Collapse
Affiliation(s)
- Holly V Moeller
- Department of Ecology, Evolution, and Marine Biology, University of California - Santa Barbara, Santa Barbara, California, 93106, USA
| | - Veronica Hsu
- Department of Ecology, Evolution, and Marine Biology, University of California - Santa Barbara, Santa Barbara, California, 93106, USA
| | - Michelle Lepori-Bui
- Department of Ecology, Evolution, and Marine Biology, University of California - Santa Barbara, Santa Barbara, California, 93106, USA
| | - Lisa Y Mesrop
- Department of Ecology, Evolution, and Marine Biology, University of California - Santa Barbara, Santa Barbara, California, 93106, USA
| | - Cara Chinn
- Department of Ecology, Evolution, and Marine Biology, University of California - Santa Barbara, Santa Barbara, California, 93106, USA
| | - Matthew D Johnson
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, 02543, USA
| |
Collapse
|
9
|
Fernández-González C, Pérez-Lorenzo M, Pratt N, Moore CM, Bibby TS, Marañón E. Effects of Temperature and Nutrient Supply on Resource Allocation, Photosynthetic Strategy, and Metabolic Rates of Synechococcus sp. JOURNAL OF PHYCOLOGY 2020; 56:818-829. [PMID: 32130730 DOI: 10.1111/jpy.12983] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 02/23/2020] [Indexed: 06/10/2023]
Abstract
Temperature and nutrient supply are key factors that control phytoplankton ecophysiology, but their role is commonly investigated in isolation. Their combined effect on resource allocation, photosynthetic strategy, and metabolism remains poorly understood. To characterize the photosynthetic strategy and resource allocation under different conditions, we analyzed the responses of a marine cyanobacterium (Synechococcus PCC 7002) to multiple combinations of temperature and nutrient supply. We measured the abundance of proteins involved in the dark (RuBisCO, rbcL) and light (Photosystem II, psbA) photosynthetic reactions, the content of chlorophyll a, carbon and nitrogen, and the rates of photosynthesis, respiration, and growth. We found that rbcL and psbA abundance increased with nutrient supply, whereas a temperature-induced increase in psbA occurred only in nutrient-replete treatments. Low temperature and abundant nutrients caused increased RuBisCO abundance, a pattern we observed also in natural phytoplankton assemblages across a wide latitudinal range. Photosynthesis and respiration increased with temperature only under nutrient-sufficient conditions. These results suggest that nutrient supply exerts a stronger effect than temperature upon both photosynthetic protein abundance and metabolic rates in Synechococcus sp. and that the temperature effect on photosynthetic physiology and metabolism is nutrient dependent. The preferential resource allocation into the light instead of the dark reactions of photosynthesis as temperature rises is likely related to the different temperature dependence of dark-reaction enzymatic rates versus photochemistry. These findings contribute to our understanding of the strategies for photosynthetic energy allocation in phytoplankton inhabiting contrasting environments.
Collapse
Affiliation(s)
| | - María Pérez-Lorenzo
- Department of Ecology and Animal Biology, Universidade de Vigo, 36310, Vigo, Spain
| | - Nicola Pratt
- Ocean and Earth Science, University of Southampton, SO14 3ZH, Southampton, UK
| | - C Mark Moore
- Ocean and Earth Science, University of Southampton, SO14 3ZH, Southampton, UK
| | - Thomas S Bibby
- Ocean and Earth Science, University of Southampton, SO14 3ZH, Southampton, UK
| | - Emilio Marañón
- Department of Ecology and Animal Biology, Universidade de Vigo, 36310, Vigo, Spain
| |
Collapse
|
10
|
Smyth TJ, Tarran GA, Sathyendranath S. Marine picoplankton size distribution and optical property contrasts throughout the Atlantic Ocean revealed using flow cytometry. APPLIED OPTICS 2019; 58:8802-8815. [PMID: 31873658 DOI: 10.1364/ao.58.008802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 10/05/2019] [Indexed: 06/10/2023]
Abstract
Depth-resolved flow cytometric observations have been used to determine the size distribution and refractive index (RI) of picoplankton throughout the Atlantic Ocean. Prochlorococcus frequently showed double size distribution peaks centered on ${0.75 \pm 0.25}$0.75±0.25 and ${1.75 \pm 0.25}\,\,{\rm \unicode{x00B5}{\rm m}}$1.75±0.25µm; the smallest peak diameters were ${\le}{0.65}\,\,{\rm \unicode{x00B5}{\rm m}}$≤0.65µm in the equatorial upwelling with larger cells (${\sim}{0.95}\,\,{\rm \unicode{x00B5}{\rm m}}$∼0.95µm) in the surface layers of the tropical gyres. Synechococcus was strongly monodispersed: the smallest (${\sim}{1.5}\,\,{\rm \unicode{x00B5}{\rm m}}$∼1.5µm) and largest cells (${\sim}{2.25{-}2.50}\,\,{\rm \unicode{x00B5}{\rm m}}$∼2.25-2.50µm) were encountered in the lowest and highest abundance regions, respectively. Typical RI for Prochlorococcus was found to be ${\sim}{1.06}$∼1.06, whereas for Synechococcus surface RI varied between 1.04-1.08 at high and low abundances, respectively.
Collapse
|
11
|
Fuchsman CA, Palevsky HI, Widner B, Duffy M, Carlson MCG, Neibauer JA, Mulholland MR, Keil RG, Devol AH, Rocap G. Cyanobacteria and cyanophage contributions to carbon and nitrogen cycling in an oligotrophic oxygen-deficient zone. ISME JOURNAL 2019; 13:2714-2726. [PMID: 31249393 PMCID: PMC6794308 DOI: 10.1038/s41396-019-0452-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 04/20/2019] [Accepted: 05/26/2019] [Indexed: 12/03/2022]
Abstract
Up to half of marine N losses occur in oxygen-deficient zones (ODZs). Organic matter flux from productive surface waters is considered a primary control on N2 production. Here we investigate the offshore Eastern Tropical North Pacific (ETNP) where a secondary chlorophyll a maximum resides within the ODZ. Rates of primary production and carbon export from the mixed layer and productivity in the primary chlorophyll a maximum were consistent with oligotrophic waters. However, sediment trap carbon and nitrogen fluxes increased between 105 and 150 m, indicating organic matter production within the ODZ. Metagenomic and metaproteomic characterization indicated that the secondary chlorophyll a maximum was attributable to the cyanobacterium Prochlorococcus, and numerous photosynthesis and carbon fixation proteins were detected. The presence of chemoautotrophic ammonia-oxidizing archaea and the nitrite oxidizer Nitrospina and detection of nitrate oxidoreductase was consistent with cyanobacterial oxygen production within the ODZ. Cyanobacteria and cyanophage were also present on large (>30 μm) particles and in sediment trap material. Particle cyanophage-to-host ratio exceeded 50, suggesting that viruses help convert cyanobacteria into sinking organic matter. Nitrate reduction and anammox proteins were detected, congruent with previously reported N2 production. We suggest that autochthonous organic matter production within the ODZ contributes to N2 production in the offshore ETNP.
Collapse
Affiliation(s)
- Clara A Fuchsman
- School of Oceanography, University of Washington, Seattle, WA, USA. .,Horn Point Laboratory, University of Maryland, Cambridge, MD, USA.
| | - Hilary I Palevsky
- School of Oceanography, University of Washington, Seattle, WA, USA.,Geosciences Department, Wellesley College, Wellesley, MA, USA
| | - Brittany Widner
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.,Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, VA, USA
| | - Megan Duffy
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Michael C G Carlson
- School of Oceanography, University of Washington, Seattle, WA, USA.,Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | | | - Margaret R Mulholland
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Richard G Keil
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Allan H Devol
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Gabrielle Rocap
- School of Oceanography, University of Washington, Seattle, WA, USA.
| |
Collapse
|
12
|
Wei Y, Zhao X, Sun J, Liu H. Fast Repetition Rate Fluorometry (FRRF) Derived Phytoplankton Primary Productivity in the Bay of Bengal. Front Microbiol 2019; 10:1164. [PMID: 31244786 PMCID: PMC6544007 DOI: 10.3389/fmicb.2019.01164] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 05/07/2019] [Indexed: 11/13/2022] Open
Abstract
The approach of fast repetition rate fluorometry (FRRF) requires a conversion factor (Φe : C/n PSII) to derive ecologically-relevant carbon uptake rates (PP z,t). However, the required Φe : C/n PSII is commonly measured by 14C assimilation and varies greatly across phytoplankton taxonomy and environmental conditions. Consequently, the use of FRRF to estimate gross primary productivity (GP z,t), alone or in combination with other approaches, has been restricted by both inherent conversion and procedural inconsistencies. Within this study, based on a hypothesis that the non-photochemical quenching (NPQNSV) can be used as a proxy for the variability and magnitude of Φe : C/n PSII, we thus proposed an independent field model coupling with the NPQNSV-based Φe : C/n PSII for FRRF-derived carbon, without the need for additional Φe : C/n PSII in the Bay of Bengal (BOB). Therewith, this robust algorithm was verified by the parallel measures of electron transport rates and 14C-uptake PP z,t. NPQNSV is theoretically caused by the effects of excess irradiance pressure, however, it showed a light and depth-independent response on large spatial scales of the BOB. Trends observed for the maximum quantum efficiency (Fv/Fm), the quantum efficiency of energy conversion ( F q ' / F m ' ) and the efficiency of charge separation ( F q ' / F v ' ) were similar and representative, which displayed a relative maximum at the subsurface and were collectively limited by excess irradiance. In particular, most observed values of Fv/Fm in the BOB were only about half of the values expected for nutrient replete phytoplankton. FRRF-based estimates of electron transport at PSII (ETRRCII) varied significantly, from 0.01 to 8.01 mol e- mol RCII-1 s-1, and showed profound responses to depth and irradiance across the BOB, but fitting with the logistic model. N, P, and irradiance are key environmental drivers in explaining the broad-scale variability of photosynthetic parameters. Furthermore, taxonomic shifts and physiological changes may be better predictors of photosynthetic parameters, and facilitate the selection of better adapted species to optimize photosynthetic efficiency under any particular set of ambient light condition.
Collapse
Affiliation(s)
- Yuqiu Wei
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Xiangwei Zhao
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Jun Sun
- Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, China.,Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin University of Science and Technology, Tianjin, China
| | - Haijiao Liu
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| |
Collapse
|
13
|
Revisiting the distribution of oceanic N 2 fixation and estimating diazotrophic contribution to marine production. Nat Commun 2019; 10:831. [PMID: 30783106 PMCID: PMC6381160 DOI: 10.1038/s41467-019-08640-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 01/22/2019] [Indexed: 12/26/2022] Open
Abstract
Marine N2 fixation supports a significant portion of oceanic primary production by making N2 bioavailable to planktonic communities, in the process influencing atmosphere-ocean carbon fluxes and our global climate. However, the geographical distribution and controlling factors of marine N2 fixation remain elusive largely due to sparse observations. Here we present unprecedented high-resolution underway N2 fixation estimates across over 6000 kilometers of the western North Atlantic. Unexpectedly, we find increasing N2 fixation rates from the oligotrophic Sargasso Sea to North America coastal waters, driven primarily by cyanobacterial diazotrophs. N2 fixation is best correlated to phosphorus availability and chlorophyll-a concentration. Globally, intense N2 fixation activity in the coastal oceans is validated by a meta-analysis of published observations and we estimate the annual coastal N2 fixation flux to be 16.7 Tg N. This study broadens the biogeography of N2 fixation, highlights the interplay of regulating factors, and reveals thriving diazotrophic communities in coastal waters with potential significance to the global nitrogen and carbon cycles. The geographical distribution and controlling factors of marine N2 fixation are understudied. Here the authors find increasing rates of N2 fixation from the Sargasso Sea to the coastal waters of North America, driven primarily by cyanobacterial diazotrophs and best correlated with phosphorus availability and chlorophyll-a concentrations.
Collapse
|
14
|
Ekins-Coward T, Boodhoo KVK, Velasquez-Orta S, Caldwell G, Wallace A, Barton R, Flickinger MC. A Microalgae Biocomposite-Integrated Spinning Disk Bioreactor (SDBR): Toward a Scalable Engineering Approach for Bioprocess Intensification in Light-Driven CO 2 Absorption Applications. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.8b05487] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Thea Ekins-Coward
- Chemical Engineering, School of Engineering, Merz Court, Newcastle University, Newcastle Upon Tyne, NE1 7RU, United Kingdom
| | - Kamelia V. K. Boodhoo
- Chemical Engineering, School of Engineering, Merz Court, Newcastle University, Newcastle Upon Tyne, NE1 7RU, United Kingdom
| | - Sharon Velasquez-Orta
- Chemical Engineering, School of Engineering, Merz Court, Newcastle University, Newcastle Upon Tyne, NE1 7RU, United Kingdom
| | - Gary Caldwell
- Marine Science, School of Natural and Environmental Sciences, Ridley Building, Newcastle University, Newcastle Upon Tyne, United Kingdom, NE1 7RU
| | - Adam Wallace
- Chemical and Biomolecular Engineering, Engineering Building 1, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Ryan Barton
- Chemical and Biomolecular Engineering, Engineering Building 1, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Michael C. Flickinger
- Chemical and Biomolecular Engineering, Engineering Building 1, North Carolina State University, Raleigh, North Carolina 27695, United States
- Golden LEAF Biomanufacturing Training and Education Center, BTEC, North Carolina State University, Raleigh, North Carolina 27695, United States
| |
Collapse
|
15
|
Hughes DJ, Campbell DA, Doblin MA, Kromkamp JC, Lawrenz E, Moore CM, Oxborough K, Prášil O, Ralph PJ, Alvarez MF, Suggett DJ. Roadmaps and Detours: Active Chlorophyll- a Assessments of Primary Productivity Across Marine and Freshwater Systems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:12039-12054. [PMID: 30247887 DOI: 10.1021/acs.est.8b03488] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Assessing phytoplankton productivity over space and time remains a core goal for oceanographers and limnologists. Fast Repetition Rate fluorometry (FRRf) provides a potential means to realize this goal with unprecedented resolution and scale yet has not become the "go-to" method despite high expectations. A major obstacle is difficulty converting electron transfer rates to equivalent rates of C-fixation most relevant for studies of biogeochemical C-fluxes. Such difficulty stems from methodological inconsistencies and our limited understanding of how the electron requirement for C-fixation (Φe,C) is influenced by the environment and by differences in the composition and physiology of phytoplankton assemblages. We outline a "roadmap" for limiting methodological bias and to develop a more mechanistic understanding of the ecophysiology underlying Φe,C. We 1) re-evaluate core physiological processes governing how microalgae invest photosynthetic electron transport-derived energy and reductant into stored carbon versus alternative sinks. Then, we 2) outline steps to facilitate broader uptake and exploitation of FRRf, which could transform our knowledge of aquatic primary productivity. We argue it is time to 3) revise our historic methodological focus on carbon as the currency of choice, to 4) better appreciate that electron transport fundamentally drives ecosystem biogeochemistry, modulates cell-to-cell interactions, and ultimately modifies community biomass and structure.
Collapse
Affiliation(s)
- David J Hughes
- Climate Change Cluster , University of Technology Sydney , Ultimo, Sydney 2007 , New South Wales , Australia
| | - Douglas A Campbell
- Department of Biology , Mount Allison University , Sackville , New Brunswick E4L 1E4 , Canada
| | - Martina A Doblin
- Climate Change Cluster , University of Technology Sydney , Ultimo, Sydney 2007 , New South Wales , Australia
| | - Jacco C Kromkamp
- Department of Estuarine and Delta Systems , NIOZ Royal Netherlands Institute for Sea Research and Utrecht University , P.O. Box 140, 4401 NT Yerseke , The Netherlands
| | - Evelyn Lawrenz
- Centre Algatech , Institute of Microbiology, Czech Academy of Sciences , Třeboň 379 81 , Czech Republic
| | - C Mark Moore
- Ocean and Earth Science , University of Southampton, National Oceanography Centre, Southampton , European Way , Southampton SO14 3ZH , U.K
| | | | - Ondřej Prášil
- Centre Algatech , Institute of Microbiology, Czech Academy of Sciences , Třeboň 379 81 , Czech Republic
| | - Peter J Ralph
- Climate Change Cluster , University of Technology Sydney , Ultimo, Sydney 2007 , New South Wales , Australia
| | - Marco F Alvarez
- Climate Change Cluster , University of Technology Sydney , Ultimo, Sydney 2007 , New South Wales , Australia
| | - David J Suggett
- Climate Change Cluster , University of Technology Sydney , Ultimo, Sydney 2007 , New South Wales , Australia
| |
Collapse
|
16
|
Huang Y, Liu X, Laws EA, Chen B, Li Y, Xie Y, Wu Y, Gao K, Huang B. Effects of increasing atmospheric CO 2 on the marine phytoplankton and bacterial metabolism during a bloom: A coastal mesocosm study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 633:618-629. [PMID: 29597159 DOI: 10.1016/j.scitotenv.2018.03.222] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/23/2018] [Accepted: 03/19/2018] [Indexed: 05/19/2023]
Abstract
Increases of atmospheric CO2 concentrations due to human activity and associated effects on aquatic ecosystems are recognized as an environmental issue at a global scale. Growing attention is being paid to CO2 enrichment effects under multiple stresses or fluctuating environmental conditions in order to extrapolate from laboratory-scale experiments to natural systems. We carried out a mesocosm experiment in coastal water with an assemblage of three model phytoplankton species and their associated bacteria under the influence of elevated CO2 concentrations. Net community production and the metabolic characteristics of the phytoplankton and bacteria were monitored to elucidate how these organisms responded to CO2 enrichment during the course of the algal bloom. We found that CO2 enrichment (1000μatm) significantly enhanced gross primary production and the ratio of photosynthesis to chlorophyll a by approximately 38% and 39%, respectively, during the early stationary phase of the algal bloom. Although there were few effects on bulk bacterial production, a significant decrease of bulk bacterial respiration (up to 31%) at elevated CO2 resulted in an increase of bacterial growth efficiency. The implication is that an elevation of CO2 concentrations leads to a reduction of bacterial carbon demand and enhances carbon transfer efficiency through the microbial loop, with a greater proportion of fixed carbon being allocated to bacterial biomass and less being lost as CO2. The contemporaneous responses of phytoplankton and bacterial metabolism to CO2 enrichment increased net community production by about 45%, an increase that would have profound implications for the carbon cycle in coastal marine ecosystems.
Collapse
Affiliation(s)
- Yibin Huang
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, China
| | - Xin Liu
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, China
| | - Edward A Laws
- Department of Environmental Sciences, College of the Coast and Environment, Louisiana State University, Baton Rouge, LA, USA
| | - Bingzhang Chen
- Ecosystem Dynamics Research Group, Research and Development Center for Global Change, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
| | - Yan Li
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - Yuyuan Xie
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, China
| | - Yaping Wu
- College of Oceanography, Hohai University, Nanjing, China
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China.
| | - Bangqin Huang
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Fujian Provincial Key Laboratory of Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, China.
| |
Collapse
|
17
|
Briggs N, Guðmundsson K, Cetinić I, D’Asaro E, Rehm E, Lee C, Perry MJ. A multi-method autonomous assessment of primary productivity and export efficiency in the springtime North Atlantic. BIOGEOSCIENCES (ONLINE) 2018; 15:4515-4532. [PMID: 32676124 PMCID: PMC7365287 DOI: 10.5194/bg-15-4515-2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fixation of organic carbon by phytoplankton is the foundation of nearly all open-ocean ecosystems and a critical part of the global carbon cycle. But quantification and validation of ocean primary productivity at large scale remains a major challenge, due to limited coverage of ship-based measurements and the difficulty of validating diverse measurement techniques. Accurate primary productivity measurements from autonomous platforms would be highly desirable, due to much greater potential coverage. In pursuit of this goal we estimate gross primary productivity over two months in the springtime North Atlantic from an autonomous Lagrangian float using diel cycles of particulate organic carbon derived from optical beam attenuation. We test method precision and accuracy by comparison against entirely independent estimates from a locally parameterized model based on chlorophyll a and light measurements from the same float. During nutrient replete conditions (80% of the study period), we obtain strong relative agreement between the independent methods across an order of magnitude of productivities (r2=0.97), with slight under-estimation by the diel cycles method (-19±5 %). At the end of the diatom bloom, this relative difference increases to -58 % for a six-day period, likely a response to SiO4 limitation, which is not included in the model. In addition, we estimate gross oxygen productivity from O2 diel cycles and find strong correlation with diel cycles-based gross primary productivity over the entire deployment, providing further qualitative support to both methods. Finally, simultaneous estimates of net community productivity, carbon export and particle size suggest that bloom growth is halted by a combination of reduced productivity due to SiO4 limitation and increased export efficiency due to rapid aggregation. After the diatom bloom, high chlorophyll a normalized productivity indicates that low net growth during this period is due to increased heterotrophic respiration and not nutrient limitation. These findings represent a significant advance in the accuracy and completeness of upper ocean carbon cycle measurements from an autonomous platform.
Collapse
Affiliation(s)
- Nathan Briggs
- National Oceanography Centre, Southampton SO14 3ZH, UK
| | | | - Ivona Cetinić
- GESTAR/Universities Space Research Association, 7178 Columbia Gateway Drive, Columbia, MD 21046, USA
- Ocean Ecology Laboratory, NASA Goddard Space Flight Center Code 616, Greenbelt, MD 20771, USA
| | - Eric D’Asaro
- Applied Physics Laboratory and School of Oceanography, University of Washington, Seattle, WA 98105, USA
| | - Eric Rehm
- Département de Biologie et Québec-Océan, Université Laval, Québec, QC G1V 0A6, Québec, Canada
| | - Craig Lee
- Applied Physics Laboratory and School of Oceanography, University of Washington, Seattle, WA 98105, USA
| | - Mary Jane Perry
- Darling Marine Center, School of Marine Sciences, University of Maine, Walpole, ME 04573, USA
| |
Collapse
|
18
|
Ducklow HW, Stukel MR, Eveleth R, Doney SC, Jickells T, Schofield O, Baker AR, Brindle J, Chance R, Cassar N. Spring-summer net community production, new production, particle export and related water column biogeochemical processes in the marginal sea ice zone of the Western Antarctic Peninsula 2012-2014. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:20170177. [PMID: 29760119 PMCID: PMC5954475 DOI: 10.1098/rsta.2017.0177] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/14/2018] [Indexed: 06/08/2023]
Abstract
New production (New P, the rate of net primary production (NPP) supported by exogenously supplied limiting nutrients) and net community production (NCP, gross primary production not consumed by community respiration) are closely related but mechanistically distinct processes. They set the carbon balance in the upper ocean and define an upper limit for export from the system. The relationships, relative magnitudes and variability of New P (from 15NO3- uptake), O2 : argon-based NCP and sinking particle export (based on the 238U : 234Th disequilibrium) are increasingly well documented but still not clearly understood. This is especially true in remote regions such as polar marginal ice zones. Here we present a 3-year dataset of simultaneous measurements made at approximately 50 stations along the Western Antarctic Peninsula (WAP) continental shelf in midsummer (January) 2012-2014. Net seasonal-scale changes in water column inventories (0-150 m) of nitrate and iodide were also estimated at the same stations. The average daily rates based on inventory changes exceeded the shorter-term rate measurements. A major uncertainty in the relative magnitude of the inventory estimates is specifying the start of the growing season following sea-ice retreat. New P and NCP(O2) did not differ significantly. New P and NCP(O2) were significantly greater than sinking particle export from thorium-234. We suggest this is a persistent and systematic imbalance and that other processes such as vertical mixing and advection of suspended particles are important export pathways.This article is part of the theme issue 'The marine system of the west Antarctic Peninsula: status and strategy for progress in a region of rapid change'.
Collapse
Affiliation(s)
- Hugh W Ducklow
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA
| | - Michael R Stukel
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA
| | - Rachel Eveleth
- Nicholas School of Environment, Duke University, Durham, NC, USA
| | - Scott C Doney
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA
| | - Tim Jickells
- School of Environmental Sciences, University of East Anglia, Norwich, UK
| | - Oscar Schofield
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA
| | - Alex R Baker
- School of Environmental Sciences, University of East Anglia, Norwich, UK
| | - John Brindle
- School of Environmental Sciences, University of East Anglia, Norwich, UK
| | - Rosie Chance
- School of Environmental Sciences, University of East Anglia, Norwich, UK
| | - Nicolas Cassar
- Nicholas School of Environment, Duke University, Durham, NC, USA
| |
Collapse
|
19
|
Du N, Gholami P, Kline DI, DuPont CL, Dickson AG, Mendola D, Martz T, Allen AE, Mitchell BG. Simultaneous quantum yield measurements of carbon uptake and oxygen evolution in microalgal cultures. PLoS One 2018; 13:e0199125. [PMID: 29920568 PMCID: PMC6008153 DOI: 10.1371/journal.pone.0199125] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 06/03/2018] [Indexed: 01/09/2023] Open
Abstract
The photosynthetic quantum yield (Φ), defined as carbon fixed or oxygen evolved per unit of light absorbed, is a fundamental but rarely determined biophysical parameter. A method to estimate Φ for both net carbon uptake and net oxygen evolution simultaneously can provide important insights into energy and mass fluxes. Here we present details for a novel system that allows quantification of carbon fluxes using pH oscillation and simultaneous oxygen fluxes by integration with a membrane inlet mass spectrometer. The pHOS system was validated using Phaeodactylum tricornutum cultured with continuous illumination of 110 μmole quanta m-2 s-1 at 25°C. Furthermore, simultaneous measurements of carbon and oxygen flux using the pHOS-MIMS and photon flux based on spectral absorption were carried out to explore the kinetics of Φ in P. tricornutum during its acclimation from low to high light (110 to 750 μmole quanta m-2 s-1). Comparing results at 0 and 24 hours, we observed strong decreases in cellular chlorophyll a (0.58 to 0.21 pg cell-1), Fv/Fm (0.71 to 0.59) and maximum ΦCO2 (0.019 to 0.004) and ΦO2 (0.028 to 0.007), confirming the transition toward high light acclimation. The Φ time-series indicated a non-synchronized acclimation response between carbon uptake and oxygen evolution, which has been previously inferred based on transcriptomic changes for a similar experimental design with the same diatom that lacked physiological data. The integrated pHOS-MIMS system can provide simultaneous carbon and oxygen measurements accurately, and at the time-resolution required to resolve high-resolution carbon and oxygen physiological dynamics.
Collapse
Affiliation(s)
- Niu Du
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
- J. Craig Venter Institute, La Jolla, California, United States of America
| | - Pardis Gholami
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
- J. Craig Venter Institute, La Jolla, California, United States of America
| | - David I. Kline
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
- Smithsonian Tropical Research Institute, Apartado, Republic of Panama
| | | | - Andrew G. Dickson
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
| | - Dominick Mendola
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
| | - Todd Martz
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
| | - Andrew E. Allen
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
- J. Craig Venter Institute, La Jolla, California, United States of America
- * E-mail: ,
| | - B. Greg Mitchell
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
| |
Collapse
|
20
|
Wang S, Lin Y, Gifford S, Eveleth R, Cassar N. Linking patterns of net community production and marine microbial community structure in the western North Atlantic. THE ISME JOURNAL 2018; 12:2582-2595. [PMID: 29934639 PMCID: PMC6193967 DOI: 10.1038/s41396-018-0163-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 04/03/2018] [Accepted: 05/11/2018] [Indexed: 11/09/2022]
Abstract
Marine net community production (NCP) tracks uptake of carbon by plankton communities and its potential transport to depth. Relationships between marine microbial community composition and NCP currently remain unclear despite their importance for assessing how different taxa impact carbon export. We conducted 16 and 18S rRNA gene (rDNA) sequencing on samples collected across the Western North Atlantic in parallel with high-resolution O2/Ar-derived NCP measurements. Using an internal standard technique to estimate in-situ prokaryotic and eukaryotic rDNA abundances per liter, we employed statistical approaches to relate patterns of microbial diversity to NCP. Taxonomic abundances calculated using internal standards provided valuable context to traditional relative abundance metrics. A bloom in the Mid-Atlantic Bight featured high eukaryote abundances with low eukaryotic diversity and was associated with the harmful algal bloom-forming Aureococcus anophagefferens, phagotrophic algae, heterotrophic flagellates, and particle-associated bacteria. These results show that coastal Aureococcus blooms host a distinct community associated with regionally significant peaks in NCP. Meanwhile, weak relationships between taxonomy and NCP in less-productive waters suggest that productivity across much of this region is not linked to specific microplankton taxa.
Collapse
Affiliation(s)
- Seaver Wang
- Division of Earth and Ocean Sciences, Duke University, Durham, USA
| | - Yajuan Lin
- Division of Earth and Ocean Sciences, Duke University, Durham, USA
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 UBO/CNRS/IRD/IFREMER, Institut Universitaire Européen de la Mer (IUEM), Brest, France
| | - Scott Gifford
- Department of Marine Sciences, the University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Rachel Eveleth
- Division of Earth and Ocean Sciences, Duke University, Durham, USA
- Department of Environmental Sciences, University of Virginia, Virginia, USA
| | - Nicolas Cassar
- Division of Earth and Ocean Sciences, Duke University, Durham, USA.
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 UBO/CNRS/IRD/IFREMER, Institut Universitaire Européen de la Mer (IUEM), Brest, France.
| |
Collapse
|
21
|
Baliarsingh SK, Lotliker AA, Sudheesh V, Samanta A, Das S, Vijayan AK. Response of phytoplankton community and size classes to green Noctiluca bloom in the northern Arabian Sea. MARINE POLLUTION BULLETIN 2018; 129:222-230. [PMID: 29680541 DOI: 10.1016/j.marpolbul.2018.02.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 02/18/2018] [Accepted: 02/19/2018] [Indexed: 06/08/2023]
Abstract
A comprehensive analysis on the phytoplankton ecology with special reference to different phytoplankton size classes was carried out at green Noctiluca scintillans (hereafter Noctiluca) bloom and non-bloom locations in offshore waters of the northern Arabian Sea. At the bloom locations, green Noctiluca represented a dense mono-specific proliferation with average cell density of 10.16 ± 5.806 × 104 cells-L-1 and relative abundance share of 98.63%. Active photosynthesis through prasinophytic endosymbiont was depicted from net community production magnitude reaching 85.26 mgC/m3/Day under low prey abundance. Parallel swarming of Porpita porpita, a voracious copepod feeder signified the competitive advantage of Noctiluca to have the phytoplankton prey. Average concentration of picophytoplankton biomass was eleven times lower in surface waters of non-bloom stations in comparison to bloom. Higher N:P ratio in subsurface waters of non-bloom stations signified non-utilization of nitrogenous nutrients. Green Noctiluca bloom onset subsequent to diatom rich conditions was evident from spatio-temporal ocean colour satellite imageries.
Collapse
Affiliation(s)
- S K Baliarsingh
- Indian National Centre for Ocean Information Services (INCOIS), Hyderabad 500090, India
| | - Aneesh A Lotliker
- Indian National Centre for Ocean Information Services (INCOIS), Hyderabad 500090, India.
| | - V Sudheesh
- Centre for Marine Living Resources and Ecology (CMLRE), Kochi 682037, India
| | - Alakes Samanta
- Indian National Centre for Ocean Information Services (INCOIS), Hyderabad 500090, India
| | - Sourav Das
- School of Oceanographic Studies, Jadavpur University, Kolkata 700032, India
| | - A K Vijayan
- Centre for Marine Living Resources and Ecology (CMLRE), Kochi 682037, India
| |
Collapse
|
22
|
Carbonate chemistry of an in-situ free-ocean CO 2 enrichment experiment (antFOCE) in comparison to short term variation in Antarctic coastal waters. Sci Rep 2018; 8:2816. [PMID: 29434330 PMCID: PMC5809532 DOI: 10.1038/s41598-018-21029-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 01/29/2018] [Indexed: 11/08/2022] Open
Abstract
Free-ocean CO2 enrichment (FOCE) experiments have been deployed in marine ecosystems to manipulate carbonate system conditions to those predicted in future oceans. We investigated whether the pH/carbonate chemistry of extremely cold polar waters can be manipulated in an ecologically relevant way, to represent conditions under future atmospheric CO2 levels, in an in-situ FOCE experiment in Antarctica. We examined spatial and temporal variation in local ambient carbonate chemistry at hourly intervals at two sites between December and February and compared these with experimental conditions. We successfully maintained a mean pH offset in acidified benthic chambers of -0.38 (±0.07) from ambient for approximately 8 weeks. Local diel and seasonal fluctuations in ambient pH were duplicated in the FOCE system. Large temporal variability in acidified chambers resulted from system stoppages. The mean pH, Ωarag and fCO2 values in the acidified chambers were 7.688 ± 0.079, 0.62 ± 0.13 and 912 ± 150 µatm, respectively. Variation in ambient pH appeared to be mainly driven by salinity and biological production and ranged from 8.019 to 8.192 with significant spatio-temporal variation. This experiment demonstrates the utility of FOCE systems to create conditions expected in future oceans that represent ecologically relevant variation, even under polar conditions.
Collapse
|
23
|
Xiao W, Liu X, Irwin AJ, Laws EA, Wang L, Chen B, Zeng Y, Huang B. Warming and eutrophication combine to restructure diatoms and dinoflagellates. WATER RESEARCH 2018; 128:206-216. [PMID: 29107905 DOI: 10.1016/j.watres.2017.10.051] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 09/27/2017] [Accepted: 10/23/2017] [Indexed: 05/20/2023]
Abstract
Temperature change and eutrophication are known to affect phytoplankton communities, but relatively little is known about the effects of interactions between simultaneous changes of temperature and nutrient loading in coastal ecosystems. Here we show that such interaction is key in driving diatom-dinoflagellate dynamics in the East China Sea. Diatoms and dinoflagellates responded differently to temperature, nutrient concentrations and ratios, and their interactions. Diatoms preferred lower temperature and higher nutrient concentrations, while dinoflagellates were less sensitive to temperature and nutrient concentrations, but tended to prevail at low phosphorus and high N:P ratio conditions. These different traits of diatoms and dinoflagellates resulted in the fact that both the effect of warming resulting in nutrients decline as a consequence of increasing stratification and the effect of increasing terrestrial nutrient input as a result of eutrophication might promote dinoflagellates over diatoms. We predict that conservative forecasts of environmental change by the year 2100 are likely to result in the decrease of diatoms in 60% and the increase of dinoflagellates in 70% of the surface water of the East China Sea, and project that mean diatoms should decrease by 19% while mean dinoflagellates should increase by 60% in the surface water of the coastal East China Sea. This analysis is based on a series of statistical niche models of the consequences of multiple environmental changes on diatom and dinoflagellate biomass in the East China Sea based on 2815 samples randomly collected from 23 cruises spanning 14 years (2002-2015). Our findings reveal that dinoflagellate blooms will be more frequent and intense, which will affect coastal ecosystem functioning.
Collapse
Affiliation(s)
- Wupeng Xiao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Key Laboratory of Coastal and Wetland Ecosystems, Ministry of Education/Fujian Provincial Key Laboratory of Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, China
| | - Xin Liu
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Key Laboratory of Coastal and Wetland Ecosystems, Ministry of Education/Fujian Provincial Key Laboratory of Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, China
| | - Andrew J Irwin
- Department of Mathematics & Computer Science, Mount Allison University, Sackville, New Brunswick, Canada
| | - Edward A Laws
- Department of Environmental Sciences, School of the Coast & Environment, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Lei Wang
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Key Laboratory of Coastal and Wetland Ecosystems, Ministry of Education/Fujian Provincial Key Laboratory of Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, China
| | - Bingzhang Chen
- Ecosystem Dynamics Research Group, Research and Development Center for Global Change, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
| | - Yang Zeng
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Key Laboratory of Coastal and Wetland Ecosystems, Ministry of Education/Fujian Provincial Key Laboratory of Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, China
| | - Bangqin Huang
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Key Laboratory of Coastal and Wetland Ecosystems, Ministry of Education/Fujian Provincial Key Laboratory of Coastal Ecology and Environmental Studies, Xiamen University, Xiamen, China.
| |
Collapse
|
24
|
Specific eukaryotic plankton are good predictors of net community production in the Western Antarctic Peninsula. Sci Rep 2017; 7:14845. [PMID: 29093494 PMCID: PMC5665988 DOI: 10.1038/s41598-017-14109-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 10/03/2017] [Indexed: 11/08/2022] Open
Abstract
Despite our current realization of the tremendous diversity that exists in plankton communities, we have little understanding of how this biodiversity influences the biological carbon pump other than broad paradigms such as diatoms contributing disproportionally to carbon export. Here we combine high-resolution underway O2/Ar, which provides an estimate of net community production, with high-throughput 18 S ribosomal DNA sequencing to elucidate the relationship between eukaryotic plankton community structure and carbon export potential at the Western Antarctica Peninsula (WAP), a region which has experienced rapid warming and ecosystem changes. Our results show that in a diverse plankton system comprised of ~464 operational taxonomic units (OTUs) with at least 97% 18 S identity, as few as two or three key OTUs, i.e. large diatoms, Phaeocystis, and mixotrophic/phagotrophic dinoflagellates, can explain a large majority of the spatial variability in the carbon export potential (76-92%). Moreover, we find based on a community co-occurrence network analysis that ecosystems with lower export potential have more tightly coupled communities. Our results indicate that defining plankton communities at a deeper taxonomic resolution than by functional groups and accounting for the differences in size and coupling between groups can substantially improve organic carbon flux predictions.
Collapse
|
25
|
Wilson ST, Aylward FO, Ribalet F, Barone B, Casey JR, Connell PE, Eppley JM, Ferrón S, Fitzsimmons JN, Hayes CT, Romano AE, Turk-Kubo KA, Vislova A, Armbrust EV, Caron DA, Church MJ, Zehr JP, Karl DM, DeLong EF. Coordinated regulation of growth, activity and transcription in natural populations of the unicellular nitrogen-fixing cyanobacterium Crocosphaera. Nat Microbiol 2017; 2:17118. [DOI: 10.1038/nmicrobiol.2017.118] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 06/23/2017] [Indexed: 01/01/2023]
|
26
|
Nutrients and Phytoplankton in a Shallow, Hypereutrophic Urban Lake: Prospects for Restoration. WATER 2017. [DOI: 10.3390/w9060431] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
University Lake, a shallow, artificial, urban lake adjacent to the campus of Louisiana State University, has a long history of water quality problems, including algal blooms, fish kills, and high concentrations of fecal indicator bacteria. Periodic dredging of the lake is necessary to prevent its return to swampland. This study was undertaken to elucidate the roles of allochthonous versus autochthonous nutrients as causes of water quality problems in the lake, with the expectation that this information would help identify strategies for lake restoration. Photosynthetic rates and concentrations of inorganic nutrients and phytoplankton pigments were measured over a period of one year. More than 90% of the chlorophyll a (chl a) in the lake was accounted for by Chlorophyceae, Cyanophyceae, and Bacillariophyceae. Concentrations of chl a, which averaged 75 μg L−1, fluctuated weekly during dry weather by as much as a factor of four. Phytoplankton growth rates were about 30% higher 1–2 days after rain events than after periods of dry weather, the implication being that allochthonous nutrient loading has a significant effect on the dynamics of the phytoplankton community in the lake. Therefore, dredging of sediments will likely produce no long-term improvement in water quality. More than 100 storm drains currently discharge into the lake, and diversion of those drains may be the most cost-effective strategy for effecting a long-term improvement in water quality.
Collapse
|
27
|
Karl DM, Grabowski E. The Importance of H in Particulate Organic Matter Stoichiometry, Export and Energy Flow. Front Microbiol 2017; 8:826. [PMID: 28536570 PMCID: PMC5422955 DOI: 10.3389/fmicb.2017.00826] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 04/24/2017] [Indexed: 11/24/2022] Open
Abstract
The discipline of marine ecological stoichiometry has progressed rapidly over the past two decades, and continues to be at the forefront of microbial oceanography. Most of this effort has been focused on the elements carbon (C) and nitrogen (N), and to a lesser extent phosphorus (P), with little consideration of hydrogen (H), or the redox state of the organic matter pools despite the fact that H is the most abundant, and possibly the most important, element in biogeochemistry. Obtaining accurate estimates of the H content of organic matter, either in suspended or sinking particles, is a major analytical challenge. While many aquatic science laboratories have access to commercial "C-H-N elemental analyzers," few investigators report H values due to analytical difficulties in obtaining accurate estimates of H. Because organic compounds vary considerably in their H:C ratio and therefore in their energy content, measurements of H combined with C-specific caloric estimates will ultimately be required for a more comprehensive understanding of ecosystem dynamics.
Collapse
Affiliation(s)
- David M. Karl
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaii, HonoluluHI, USA
| | | |
Collapse
|
28
|
Ecosystem Structure and Dynamics in the North Pacific Subtropical Gyre: New Views of an Old Ocean. Ecosystems 2017. [DOI: 10.1007/s10021-017-0117-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
29
|
Jerez CG, Malapascua JR, Sergejevová M, Masojídek J, Figueroa FL. Chlorella fusca (Chlorophyta) grown in thin-layer cascades: Estimation of biomass productivity by in-vivo chlorophyll a fluorescence monitoring. ALGAL RES 2016. [DOI: 10.1016/j.algal.2016.04.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
30
|
Low rates of nitrogen fixation in eastern tropical South Pacific surface waters. Proc Natl Acad Sci U S A 2016; 113:4398-403. [PMID: 26976587 DOI: 10.1073/pnas.1515641113] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An extensive region of the Eastern Tropical South Pacific (ETSP) Ocean has surface waters that are nitrate-poor yet phosphate-rich. It has been proposed that this distribution of surface nutrients provides a geochemical niche favorable for N2fixation, the primary source of nitrogen to the ocean. Here, we present results from two cruises to the ETSP where rates of N2fixation and its contribution to export production were determined with a suite of geochemical and biological measurements. N2fixation was only detectable using nitrogen isotopic mass balances at two of six stations, and rates ranged from 0 to 23 µmol N m(-2)d(-1)based on sediment trap fluxes. Whereas the fractional importance of N2fixation did not change, the N2-fixation rates at these two stations were several-fold higher when scaled to other productivity metrics. Regardless of the choice of productivity metric these N2-fixation rates are low compared with other oligotrophic locations, and the nitrogen isotope budgets indicate that N2fixation supports no more than 20% of export production regionally. Although euphotic zone-integrated short-term N2-fixation rates were higher, up to 100 µmol N m(-2)d(-1), and detected N2fixation at all six stations, studies of nitrogenase gene abundance and expression from the same cruises align with the geochemical data and together indicate that N2fixation is a minor source of new nitrogen to surface waters of the ETSP. This finding is consistent with the hypothesis that, despite a relative abundance of phosphate, iron may limit N2fixation in the ETSP.
Collapse
|
31
|
Svedén JB, Adam B, Walve J, Nahar N, Musat N, Lavik G, Whitehouse MJ, Kuypers MMM, Ploug H. High cell-specific rates of nitrogen and carbon fixation by the cyanobacterium Aphanizomenon sp. at low temperatures in the Baltic Sea. FEMS Microbiol Ecol 2015; 91:fiv131. [PMID: 26511856 DOI: 10.1093/femsec/fiv131] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/23/2015] [Indexed: 11/14/2022] Open
Abstract
Aphanizomenon is a widespread genus of nitrogen (N2)-fixing cyanobacteria in lakes and estuaries, accounting for a large fraction of the summer N2-fixation in the Baltic Sea. However, information about its cell-specific carbon (C)- and N2-fixation rates in the early growth season has not previously been reported. We combined various methods to study N2-fixation, photosynthesis and respiration in field-sampled Baltic Sea Aphanizomenon sp. during early summer at 10°C. Stable isotope incubations at in situ light intensities during 24 h combined with cell-specific secondary ion mass spectrometry showed an average net N2-fixation rate of 55 fmol N cell(-1) day(-1). Dark net N2-fixation rates over a course of 12 h were 20% of those measured in light. C-fixation, but not N2-fixation, was inhibited by high ambient light intensities during daytime. Consequently, the C:N fixation ratio varied substantially over the diel cycle. C- and N2-fixation rates were comparable to those reported for Aphanizomenon sp. in August at 19°C, using the same methods. High respiration rates (23% of gross photosynthesis) were measured with (14)C-incubations and O2-microsensors, and presumably reflect the energy needed for high N2-fixation rates. Hence, Aphanizomenon sp. is an important contributor to N2-fixation at low in situ temperatures in the early growth season.
Collapse
Affiliation(s)
- Jennie B Svedén
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-10691 Stockholm, Sweden
| | - Birgit Adam
- Max Planck Institute for Marine Microbiology, Celsiusstr. 1, DE-28359 Bremen, Germany
| | - Jakob Walve
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-10691 Stockholm, Sweden
| | - Nurun Nahar
- Department of Marine Sciences, University of Gothenburg, Box 460, SE-405 30 Gothenburg, Sweden
| | - Niculina Musat
- Max Planck Institute for Marine Microbiology, Celsiusstr. 1, DE-28359 Bremen, Germany Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, DE-04318 Leipzig, Germany
| | - Gaute Lavik
- Max Planck Institute for Marine Microbiology, Celsiusstr. 1, DE-28359 Bremen, Germany
| | | | - Marcel M M Kuypers
- Max Planck Institute for Marine Microbiology, Celsiusstr. 1, DE-28359 Bremen, Germany
| | - Helle Ploug
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-10691 Stockholm, Sweden Department of Marine Sciences, University of Gothenburg, Box 460, SE-405 30 Gothenburg, Sweden
| |
Collapse
|
32
|
Hancke K, Dalsgaard T, Sejr MK, Markager S, Glud RN. Phytoplankton Productivity in an Arctic Fjord (West Greenland): Estimating Electron Requirements for Carbon Fixation and Oxygen Production. PLoS One 2015. [PMID: 26218096 PMCID: PMC4517866 DOI: 10.1371/journal.pone.0133275] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Accurate quantification of pelagic primary production is essential for quantifying the marine carbon turnover and the energy supply to the food web. Knowing the electron requirement (Κ) for carbon (C) fixation (ΚC) and oxygen (O2) production (ΚO2), variable fluorescence has the potential to quantify primary production in microalgae, and hereby increasing spatial and temporal resolution of measurements compared to traditional methods. Here we quantify ΚC and ΚO2 through measures of Pulse Amplitude Modulated (PAM) fluorometry, C fixation and O2 production in an Arctic fjord (Godthåbsfjorden, W Greenland). Through short- (2h) and long-term (24h) experiments, rates of electron transfer (ETRPSII), C fixation and/or O2 production were quantified and compared. Absolute rates of ETR were derived by accounting for Photosystem II light absorption and spectral light composition. Two-hour incubations revealed a linear relationship between ETRPSII and gross 14C fixation (R2 = 0.81) during light-limited photosynthesis, giving a ΚC of 7.6 ± 0.6 (mean ± S.E.) mol é (mol C)−1. Diel net rates also demonstrated a linear relationship between ETRPSII and C fixation giving a ΚC of 11.2 ± 1.3 mol é (mol C)−1 (R2 = 0.86). For net O2 production the electron requirement was lower than for net C fixation giving 6.5 ± 0.9 mol é (mol O2)−1 (R2 = 0.94). This, however, still is an electron requirement 1.6 times higher than the theoretical minimum for O2 production [i.e. 4 mol é (mol O2)−1]. The discrepancy is explained by respiratory activity and non-photochemical electron requirements and the variability is discussed. In conclusion, the bio-optical method and derived electron requirement support conversion of ETR to units of C or O2, paving the road for improved spatial and temporal resolution of primary production estimates.
Collapse
Affiliation(s)
- Kasper Hancke
- Nordic Center for Earth Evolution (NordCEE), Department of Biology, University of Southern Denmark, Odense, Denmark
- Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk, Greenland
- * E-mail:
| | - Tage Dalsgaard
- Arctic Research Center, Aarhus University, Aarhus, Denmark
| | - Mikael Kristian Sejr
- Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk, Greenland
- Arctic Research Center, Aarhus University, Aarhus, Denmark
| | - Stiig Markager
- Institute for Bioscience, Aarhus University, Aarhus, Denmark
| | - Ronnie Nøhr Glud
- Nordic Center for Earth Evolution (NordCEE), Department of Biology, University of Southern Denmark, Odense, Denmark
- Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk, Greenland
- Arctic Research Center, Aarhus University, Aarhus, Denmark
- Scottish Association for Marine Science, Scottish Marine Institute, Oban, United Kingdom
| |
Collapse
|
33
|
Interacting Effects of Light and Iron Availability on the Coupling of Photosynthetic Electron Transport and CO2-Assimilation in Marine Phytoplankton. PLoS One 2015; 10:e0133235. [PMID: 26171963 PMCID: PMC4501554 DOI: 10.1371/journal.pone.0133235] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 06/25/2015] [Indexed: 12/30/2022] Open
Abstract
Iron availability directly affects photosynthesis and limits phytoplankton growth over vast oceanic regions. For this reason, the availability of iron is a crucial variable to consider in the development of active chlorophyll a fluorescence based estimates of phytoplankton primary productivity. These bio-optical approaches require a conversion factor to derive ecologically-relevant rates of CO2-assimilation from estimates of electron transport in photosystem II. The required conversion factor varies significantly across phytoplankton taxa and environmental conditions, but little information is available on its response to iron limitation. In this study, we examine the role of iron limitation, and the interacting effects of iron and light availability, on the coupling of photosynthetic electron transport and CO2-assimilation in marine phytoplankton. Our results show that excess irradiance causes increased decoupling of carbon fixation and electron transport, particularly under iron limiting conditions. We observed that reaction center II specific rates of electron transport (ETRRCII, mol e- mol RCII-1 s-1) increased under iron limitation, and we propose a simple conceptual model for this observation. We also observed a strong correlation between the derived conversion factor and the expression of non-photochemical quenching. Utilizing a dataset from in situ phytoplankton assemblages across a coastal – oceanic transect in the Northeast subarctic Pacific, this relationship was used to predict ETRRCII: CO2-assimilation conversion factors and carbon-based primary productivity from FRRF data, without the need for any additional measurements.
Collapse
|
34
|
Spilling K, Ylöstalo P, Simis S, Seppälä J. Interaction Effects of Light, Temperature and Nutrient Limitations (N, P and Si) on Growth, Stoichiometry and Photosynthetic Parameters of the Cold-Water Diatom Chaetoceros wighamii. PLoS One 2015; 10:e0126308. [PMID: 25993327 PMCID: PMC4438981 DOI: 10.1371/journal.pone.0126308] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Accepted: 03/21/2015] [Indexed: 11/18/2022] Open
Abstract
Light (20-450 μmol photons m-2 s-1), temperature (3-11°C) and inorganic nutrient composition (nutrient replete and N, P and Si limitation) were manipulated to study their combined influence on growth, stoichiometry (C:N:P:Chl a) and primary production of the cold water diatom Chaetoceros wighamii. During exponential growth, the maximum growth rate (~0.8 d-1) was observed at high temperture and light; at 3°C the growth rate was ~30% lower under similar light conditions. The interaction effect of light and temperature were clearly visible from growth and cellular stoichiometry. The average C:N:P molar ratio was 80:13:1 during exponential growth, but the range, due to different light acclimation, was widest at the lowest temperature, reaching very low C:P (~50) and N:P ratios (~8) at low light and temperature. The C:Chl a ratio had also a wider range at the lowest temperature during exponential growth, ranging 16-48 (weight ratio) at 3°C compared with 17-33 at 11°C. During exponential growth, there was no clear trend in the Chl a normalized, initial slope (α*) of the photosynthesis-irradiance (PE) curve, but the maximum photosynthetic production (Pm) was highest for cultures acclimated to the highest light and temperature. During the stationary growth phase, the stoichiometric relationship depended on the limiting nutrient, but with generally increasing C:N:P ratio. The average photosynthetic quotient (PQ) during exponential growth was 1.26 but decreased to <1 under nutrient and light limitation, probably due to photorespiration. The results clearly demonstrate that there are interaction effects between light, temperature and nutrient limitation, and the data suggests greater variability of key parameters at low temperature. Understanding these dynamics will be important for improving models of aquatic primary production and biogeochemical cycles in a warming climate.
Collapse
Affiliation(s)
- Kristian Spilling
- Finnish Environment Institute, Marine Research Centre, PO Box 140, Helsinki, Finland
- Tvärminne Zoological Station, University of Helsinki, J.A. Palménin tie 260, Hanko, Finland
- * E-mail:
| | - Pasi Ylöstalo
- Finnish Environment Institute, Marine Research Centre, PO Box 140, Helsinki, Finland
| | - Stefan Simis
- Finnish Environment Institute, Marine Research Centre, PO Box 140, Helsinki, Finland
- Plymouth Marine Laboratory, Plymouth, United Kingdom
| | - Jukka Seppälä
- Finnish Environment Institute, Marine Research Centre, PO Box 140, Helsinki, Finland
| |
Collapse
|
35
|
Ishidoya S, Murayama S, Kondo H, Saigusa N, Kishimoto-Mo AW, Yamamoto S. Observation of O2:CO2 exchange ratio for net turbulent fluxes and its application to forest carbon cycles. Ecol Res 2015. [DOI: 10.1007/s11284-014-1241-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
36
|
Halsey KH, Jones BM. Phytoplankton strategies for photosynthetic energy allocation. ANNUAL REVIEW OF MARINE SCIENCE 2014; 7:265-297. [PMID: 25149563 DOI: 10.1146/annurev-marine-010814-015813] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Phytoplankton physiology is dynamic and highly responsive to the environment. Phytoplankton acclimate to changing environmental conditions by a complex reallocation of carbon and energy through metabolic pathways to optimize growth. Considering the tremendous diversity of phytoplankton, it is not surprising that different phytoplankton taxa use different strategies to partition carbon and energy resources. It has therefore been satisfying to discover that general principles of energetic stoichiometry appear to govern these complex processes and can be broadly applied to interpret phytoplankton distributions, productivity, and food web dynamics. The expectation of future changes in aquatic environments brought on by climate change warrants gathering knowledge about underlying patterns of photosynthetic energy allocation and their impacts on community structure and ecosystem productivity.
Collapse
Affiliation(s)
- Kimberly H Halsey
- Department of Microbiology, Oregon State University, Corvallis, Oregon 97331;
| | | |
Collapse
|
37
|
A microarray for assessing transcription from pelagic marine microbial taxa. ISME JOURNAL 2014; 8:1476-91. [PMID: 24477198 DOI: 10.1038/ismej.2014.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 12/16/2013] [Accepted: 12/31/2013] [Indexed: 02/08/2023]
Abstract
Metagenomic approaches have revealed unprecedented genetic diversity within microbial communities across vast expanses of the world's oceans. Linking this genetic diversity with key metabolic and cellular activities of microbial assemblages is a fundamental challenge. Here we report on a collaborative effort to design MicroTOOLs (Microbiological Targets for Ocean Observing Laboratories), a high-density oligonucleotide microarray that targets functional genes of diverse taxa in pelagic and coastal marine microbial communities. MicroTOOLs integrates nucleotide sequence information from disparate data types: genomes, PCR-amplicons, metagenomes, and metatranscriptomes. It targets 19 400 unique sequences over 145 different genes that are relevant to stress responses and microbial metabolism across the three domains of life and viruses. MicroTOOLs was used in a proof-of-concept experiment that compared the functional responses of microbial communities following Fe and P enrichments of surface water samples from the North Pacific Subtropical Gyre. We detected transcription of 68% of the gene targets across major taxonomic groups, and the pattern of transcription indicated relief from Fe limitation and transition to N limitation in some taxa. Prochlorococcus (eHLI), Synechococcus (sub-cluster 5.3) and Alphaproteobacteria SAR11 clade (HIMB59) showed the strongest responses to the Fe enrichment. In addition, members of uncharacterized lineages also responded. The MicroTOOLs microarray provides a robust tool for comprehensive characterization of major functional groups of microbes in the open ocean, and the design can be easily amended for specific environments and research questions.
Collapse
|
38
|
|
39
|
Sackett O, Petrou K, Reedy B, De Grazia A, Hill R, Doblin M, Beardall J, Ralph P, Heraud P. Phenotypic plasticity of southern ocean diatoms: key to success in the sea ice habitat? PLoS One 2013; 8:e81185. [PMID: 24363795 PMCID: PMC3868450 DOI: 10.1371/journal.pone.0081185] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Accepted: 10/09/2013] [Indexed: 02/08/2023] Open
Abstract
Diatoms are the primary source of nutrition and energy for the Southern Ocean ecosystem. Microalgae, including diatoms, synthesise biological macromolecules such as lipids, proteins and carbohydrates for growth, reproduction and acclimation to prevailing environmental conditions. Here we show that three key species of Southern Ocean diatom (Fragilariopsis cylindrus, Chaetoceros simplex and Pseudo-nitzschia subcurvata) exhibited phenotypic plasticity in response to salinity and temperature regimes experienced during the seasonal formation and decay of sea ice. The degree of phenotypic plasticity, in terms of changes in macromolecular composition, was highly species-specific and consistent with each species’ known distribution and abundance throughout sea ice, meltwater and pelagic habitats, suggesting that phenotypic plasticity may have been selected for by the extreme variability of the polar marine environment. We argue that changes in diatom macromolecular composition and shifts in species dominance in response to a changing climate have the potential to alter nutrient and energy fluxes throughout the Southern Ocean ecosystem.
Collapse
Affiliation(s)
- Olivia Sackett
- School of the Environment and the Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, New South Wales, Australia
- School of Biological Sciences, Monash University, Victoria, Australia
| | - Katherina Petrou
- School of the Environment and the Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, New South Wales, Australia
| | - Brian Reedy
- School of Chemistry and Forensic Science, University of Technology, Sydney, New South Wales, Australia
| | - Adrian De Grazia
- School of Chemistry and Forensic Science, University of Technology, Sydney, New South Wales, Australia
| | - Ross Hill
- Centre for Marine Bio-Innovation and Sydney Institute of Marine Science, School of Biological, Earth and Environmental Sciences, The University of New South Wales, New South Wales, Australia
| | - Martina Doblin
- School of the Environment and the Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, New South Wales, Australia
| | - John Beardall
- Centre for Biospectroscopy and School of Biological Sciences, Monash University, Victoria, Australia
| | - Peter Ralph
- School of the Environment and the Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, New South Wales, Australia
| | - Philip Heraud
- Centre for Biospectroscopy and School of Biological Sciences, Monash University, Victoria, Australia
- * E-mail:
| |
Collapse
|
40
|
Lawrenz E, Silsbe G, Capuzzo E, Ylöstalo P, Forster RM, Simis SGH, Prášil O, Kromkamp JC, Hickman AE, Moore CM, Forget MH, Geider RJ, Suggett DJ. Predicting the electron requirement for carbon fixation in seas and oceans. PLoS One 2013; 8:e58137. [PMID: 23516441 PMCID: PMC3596381 DOI: 10.1371/journal.pone.0058137] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Accepted: 01/30/2013] [Indexed: 11/18/2022] Open
Abstract
Marine phytoplankton account for about 50% of all global net primary productivity (NPP). Active fluorometry, mainly Fast Repetition Rate fluorometry (FRRf), has been advocated as means of providing high resolution estimates of NPP. However, not measuring CO2-fixation directly, FRRf instead provides photosynthetic quantum efficiency estimates from which electron transfer rates (ETR) and ultimately CO2-fixation rates can be derived. Consequently, conversions of ETRs to CO2-fixation requires knowledge of the electron requirement for carbon fixation (Φe,C, ETR/CO2 uptake rate) and its dependence on environmental gradients. Such knowledge is critical for large scale implementation of active fluorescence to better characterise CO2-uptake. Here we examine the variability of experimentally determined Φe,C values in relation to key environmental variables with the aim of developing new working algorithms for the calculation of Φe,C from environmental variables. Coincident FRRf and 14C-uptake and environmental data from 14 studies covering 12 marine regions were analysed via a meta-analytical, non-parametric, multivariate approach. Combining all studies, Φe,C varied between 1.15 and 54.2 mol e− (mol C)−1 with a mean of 10.9±6.91 mol e− mol C)−1. Although variability of Φe,C was related to environmental gradients at global scales, region-specific analyses provided far improved predictive capability. However, use of regional Φe,C algorithms requires objective means of defining regions of interest, which remains challenging. Considering individual studies and specific small-scale regions, temperature, nutrient and light availability were correlated with Φe,C albeit to varying degrees and depending on the study/region and the composition of the extant phytoplankton community. At the level of large biogeographic regions and distinct water masses, Φe,C was related to nutrient availability, chlorophyll, as well as temperature and/or salinity in most regions, while light availability was also important in Baltic Sea and shelf waters. The novel Φe,C algorithms provide a major step forward for widespread fluorometry-based NPP estimates and highlight the need for further studying the natural variability of Φe,C to verify and develop algorithms with improved accuracy.
Collapse
Affiliation(s)
- Evelyn Lawrenz
- Laboratory of Photosynthesis, Institute of Microbiology, ASCR (Academy of Sciences of the Czech Republic), Opatovický mlýn, Třeboň, Czech Republic.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Juranek LW, Quay PD. Using triple isotopes of dissolved oxygen to evaluate global marine productivity. ANNUAL REVIEW OF MARINE SCIENCE 2012; 5:503-524. [PMID: 22809194 DOI: 10.1146/annurev-marine-121211-172430] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Since the triple isotopic composition of dissolved O(2) ((17)Δ) was introduced as a natural tracer of photosynthetic gross O(2) production (GOP) over 10 years ago, observations of (17)Δ have been used to constrain marine productivity throughout the global ocean. This incubation-independent approach has several advantages: It allows the determination of production free from containment artifacts and reduces logistical hurdles that can make obtaining productivity with traditional incubation-dependent methods difficult. As such, GOP estimates derived from (17)Δ have been used to give insight into potential biases in incubation-based approaches and to evaluate satellite-based estimates of production at the regional scale. With increased use, we have also learned more about the potential biases and uncertainties of this approach, some of which have been addressed by recent method improvements. We recap the major advances the (17)Δ method has brought to improved understanding of biological carbon cycling, from incubation bottles to ocean basins.
Collapse
Affiliation(s)
- L W Juranek
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA.
| | | |
Collapse
|
42
|
Juranek LW, Quay PD, Feely RA, Lockwood D, Karl DM, Church MJ. Biological production in the NE Pacific and its influence on air-sea CO2flux: Evidence from dissolved oxygen isotopes and O2/Ar. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jc007450] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
43
|
Nicholson DP, Stanley RHR, Barkan E, Karl DM, Luz B, Quay PD, Doney SC. Evaluating triple oxygen isotope estimates of gross primary production at the Hawaii Ocean Time-series and Bermuda Atlantic Time-series Study sites. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2010jc006856] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
44
|
Hamme RC, Cassar N, Lance VP, Vaillancourt RD, Bender ML, Strutton PG, Moore TS, DeGrandpre MD, Sabine CL, Ho DT, Hargreaves BR. Dissolved O2/Ar and other methods reveal rapid changes in productivity during a Lagrangian experiment in the Southern Ocean. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jc007046] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
45
|
Long MC, Dunbar RB, Tortell PD, Smith WO, Mucciarone DA, DiTullio GR. Vertical structure, seasonal drawdown, and net community production in the Ross Sea, Antarctica. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2009jc005954] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
46
|
|
47
|
Hancke K, Hancke TB, Olsen LM, Johnsen G, Glud RN. TEMPERATURE EFFECTS ON MICROALGAL PHOTOSYNTHESIS-LIGHT RESPONSES MEASURED BY O2 PRODUCTION, PULSE-AMPLITUDE-MODULATED FLUORESCENCE, AND (14) C ASSIMILATION(1). JOURNAL OF PHYCOLOGY 2008; 44:501-14. [PMID: 27041204 DOI: 10.1111/j.1529-8817.2008.00487.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Short-term temperature effects on photosynthesis were investigated by measuring O2 production, PSII-fluorescence kinetics, and (14) C-incorporation rates in monocultures of the marine phytoplankton species Prorocentrum minimum (Pavill.) J. Schiller (Dinophyceae), Prymnesium parvum f. patelliferum (J. C. Green, D. J. Hibberd et Pienaar) A. Larsen (Coccolithophyceae), and Phaeodactylum tricornutum Bohlin (Bacillariophyceae), grown at 15°C and 80 μmol photons · m(-2) · s(-1) . Photosynthesis versus irradiance curves were measured at seven temperatures (0°C-30°C) by all three approaches. The maximum photosynthetic rate (P(C) max ) was strongly stimulated by temperature, reached an optimum for Pro. minimum only (20°C-25°C), and showed a similar relative temperature response for the three applied methods, with Q10 ranging from 1.7 to 3.5. The maximum light utilization coefficient (α(C) ) was insensitive or decreased slightly with increasing temperature. Absolute rates of O2 production were calculated from pulse-amplitude-modulated (PAM) fluorometry measurements in combination with biooptical determination of absorbed quanta in PSII. The relationship between PAM-based O2 production and measured O2 production and (14) C assimilation showed a species-specific correlation, with 1.2-3.3 times higher absolute values of P(C) max and α(C) when calculated from PAM data for Pry. parvum and Ph. tricornutum but equivalent for Pro. minimum. The offset seemed to be temperature insensitive and could be explained by a lower quantum yield for O2 production than the theoretical maximum (due to Mehler-type reactions). Conclusively, the PAM technique can be used to study temperature responses of photosynthesis in microalgae when paying attention to the absorption properties in PSII.
Collapse
Affiliation(s)
- Kasper Hancke
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, NorwayMarine Biological Laboratory, University of Copenhagen, Strandpromenaden 5, DK-3000 Helsingør, Denmark
| | - Torunn B Hancke
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, NorwayMarine Biological Laboratory, University of Copenhagen, Strandpromenaden 5, DK-3000 Helsingør, Denmark
| | - Lasse M Olsen
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, NorwayMarine Biological Laboratory, University of Copenhagen, Strandpromenaden 5, DK-3000 Helsingør, Denmark
| | - Geir Johnsen
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, NorwayMarine Biological Laboratory, University of Copenhagen, Strandpromenaden 5, DK-3000 Helsingør, Denmark
| | - Ronnie N Glud
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, NorwayMarine Biological Laboratory, University of Copenhagen, Strandpromenaden 5, DK-3000 Helsingør, Denmark
| |
Collapse
|
48
|
Cassar N, Bender ML, Barnett BA, Fan S, Moxim WJ, Levy H, Tilbrook B. The Southern Ocean Biological Response to Aeolian Iron Deposition. Science 2007; 317:1067-70. [PMID: 17717181 DOI: 10.1126/science.1144602] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Biogeochemical rate processes in the Southern Ocean have an important impact on the global environment. Here, we summarize an extensive set of published and new data that establishes the pattern of gross primary production and net community production over large areas of the Southern Ocean. We compare these rates with model estimates of dissolved iron that is added to surface waters by aerosols. This comparison shows that net community production, which is comparable to export production, is proportional to modeled input of soluble iron in aerosols. Our results strengthen the evidence that the addition of aerosol iron fertilizes export production in the Southern Ocean. The data also show that aerosol iron input particularly enhances gross primary production over the large area of the Southern Ocean downwind of dry continental areas.
Collapse
Affiliation(s)
- Nicolas Cassar
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA.
| | | | | | | | | | | | | |
Collapse
|
49
|
Walsh JJ, Jolliff JK, Darrow BP, Lenes JM, Milroy SP, Remsen A, Dieterle DA, Carder KL, Chen FR, Vargo GA, Weisberg RH, Fanning KA, Muller-Karger FE, Shinn E, Steidinger KA, Heil CA, Tomas CR, Prospero JS, Lee TN, Kirkpatrick GJ, Whitledge TE, Stockwell DA, Villareal TA, Jochens AE, Bontempi PS. Red tides in the Gulf of Mexico: Where, when, and why? JOURNAL OF GEOPHYSICAL RESEARCH 2006; 111:1-46. [PMID: 20411040 PMCID: PMC2856968 DOI: 10.1029/2004jc002813] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
[1] Independent data from the Gulf of Mexico are used to develop and test the hypothesis that the same sequence of physical and ecological events each year allows the toxic dinoflagellate Karenia brevis to become dominant. A phosphorus-rich nutrient supply initiates phytoplankton succession, once deposition events of Saharan iron-rich dust allow Trichodesmium blooms to utilize ubiquitous dissolved nitrogen gas within otherwise nitrogen-poor sea water. They and the co-occurring K. brevis are positioned within the bottom Ekman layers, as a consequence of their similar diel vertical migration patterns on the middle shelf. Upon onshore upwelling of these near-bottom seed populations to CDOM-rich surface waters of coastal regions, light-inhibition of the small red tide of ~1 ug chl l(-1) of ichthytoxic K. brevis is alleviated. Thence, dead fish serve as a supplementary nutrient source, yielding large, self-shaded red tides of ~10 ug chl l(-1). The source of phosphorus is mainly of fossil origin off west Florida, where past nutrient additions from the eutrophied Lake Okeechobee had minimal impact. In contrast, the P-sources are of mainly anthropogenic origin off Texas, since both the nutrient loadings of Mississippi River and the spatial extent of the downstream red tides have increased over the last 100 years. During the past century and particularly within the last decade, previously cryptic Karenia spp. have caused toxic red tides in similar coastal habitats of other western boundary currents off Japan, China, New Zealand, Australia, and South Africa, downstream of the Gobi, Simpson, Great Western, and Kalahari Deserts, in a global response to both desertification and eutrophication.
Collapse
Affiliation(s)
- J J Walsh
- College of Marine Science, University of South Florida, St. Petersburg, Florida, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Estimating estuarine gross production, community respiration and net ecosystem production: a nonlinear inverse technique. Ecol Modell 2005. [DOI: 10.1016/j.ecolmodel.2004.10.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|