A large-volume mesocosm-based nutrient perturbation experiment was conducted off the island of Ha... more A large-volume mesocosm-based nutrient perturbation experiment was conducted off the island of Hawai‘i, USA, to investigate the response of surface ocean phytoplankton communities to the addition of macronutrients, trace metals, and vitamins and to assess the feasibility of using mesocosms in the open ocean. Three free-drifting mesocosms (~60 m3) were deployed: one mesocosm served as a control (no nutrient amendments); a second (termed +P) was amended with nitrate (N), silicate (Si), phosphate (P), and a trace metal + vitamin mixture; and a third (termed -P) was amended with N, Si, and a trace metal + vitamin mixture but no P. These mesocosms were unreplicated due to logistical constraints and hence differences between treatments are qualitative. After 6 d, the largest response of the phytoplankton community was observed in the +P mesocosm, where chlorophyll a and 14C-based primary production were 2-3× greater than in the -P mesocosm and 4-6× greater than in the control. Comparison ...
In the contemporary North Pacific subtropical gyre (NPSG) the extant microbial community is based... more In the contemporary North Pacific subtropical gyre (NPSG) the extant microbial community is based on prokaryotic cells with the cyanobacterium Prochlorococcus dominating the phototrophic component. ...
We provide here a time series of bottle-based, discrete surface (top 25 m of the water column) pa... more We provide here a time series of bottle-based, discrete surface (top 25 m of the water column) particulate carbon concentrations (PC), HPLC-based chlorophyll-a concentrations (Chl), heterotrophic bacteria counts (HBact), and adenosine-5'-triphosphate (ATP) concentrations collected nearly monthly from 2003-2018 at the Hawaii Ocean Time-series Station ALOHA (file: HOT_bottle_data.xlsx). A time series of high resolution (hourly) particulate beam attenuation coefficients are also made available collected at the same station from 2015-2020 (file: HOT_cp_data.xlsx). These data are presented and discussed in a Limnology and Oceanography Letters paper by Henderikx-Freitas, Bjorkman, Karl, and White titled "Constraining growth rates and the ratio of living to non-living particulate carbon using beam attenuation and adenosine-5'-triphosphate at Station ALOHA". See HOT_data_metadata.pdf for additional information.
The marine cyanobacterium Prochlorococcus can utilize glucose as a source of carbon. However, the... more The marine cyanobacterium Prochlorococcus can utilize glucose as a source of carbon. However, the relative importance of inorganic and organic carbon assimilation and the timing of glucose assimilation are still poorly understood in these numerically dominant cyanobacteria. Here we investigated whole microbial community and group-specific primary production and glucose assimilation, using incubations with radioisotopes combined with flow cytometry cell sorting. We also studied changes in the microbial community structure in response to glucose enrichments and analyzed the transcription of Prochlorocccus genes involved in carbon metabolism and photosynthesis.Our results showed a circadian rhythm for glucose assimilation in Prochlorococcus, with maximum assimilation during the midday and minimum at midnight, which was different compared with that of the total microbial community. This suggests that rhythms in glucose assimilation have been adapted in Prochlorococcus to couple the acti...
Publisher Summary The chapter presents the principle and stepwise procedures for the accurate est... more Publisher Summary The chapter presents the principle and stepwise procedures for the accurate estimation of (1) dissolved orthophosphate (HPO 4 2 ; hereafter referred to as “Pi”), soluble reactive P (SRP), total dissolved P (TDP) and particulate P (PP) as minimal constraints on P pool inventories; (2) dissolved and particulate adenosine-5'-triphosphate concentrations (D-ATP and P-ATP, respectively); (3) Pi uptake/regeneration and dissolved organic P (DOP) production rates using radiolabeled Pi ( 32 P or 33 P) precursors; and (4) turnover rate estimation of the α-P and γ-P of intracellular ATP. The latter measurements provide information on microbial growth rate, total energy flux and the biologically available P (BAP) pool. These methods collectively provide a protocol suite that is suitable for an initial study of P dynamics in selected marine habitats.
Biogeochemistry of Marine Dissolved Organic Matter, 2002
... Hawaii I. Introduction II. Terms, Definitions, and Concentration Units III. The Early Years o... more ... Hawaii I. Introduction II. Terms, Definitions, and Concentration Units III. The Early Years of Pelagic Marine P-cycle Research (1884-1955) IV. The Pelagic Marine P-cycle: Key Pools and Processes V. Sampling, Incubation, Storage ...
Analysis of a portion of Vostok ice core number 5G, which is thought to contain frozen water deri... more Analysis of a portion of Vostok ice core number 5G, which is thought to contain frozen water derived from Lake Vostok, Antarctica (a body of liquid water located beneath about 4 kilometers of glacial ice), revealed between 2 × 10 2 and 3 × 10 2 bacterial cells per milliliter and low concentrations of potential growth nutrients. Lipopolysaccharide (a Gram-negative bacterial cell biomarker) was also detected at concentrations consistent with the cell enumeration data, which suggests a predominance of Gram-negative bacteria. At least a portion of the microbial assemblage was viable, as determined by the respiration of carbon-14–labeled acetate and glucose substrates during incubations at 3°C and 1 atmosphere. These accreted ice data suggest that Lake Vostok may contain viable microorganisms.
Proceedings of the National Academy of Sciences, 2008
The fresh water discharged by large rivers such as the Amazon is transported hundreds to thousand... more The fresh water discharged by large rivers such as the Amazon is transported hundreds to thousands of kilometers away from the coast by surface plumes. The nutrients delivered by these river plumes contribute to enhanced primary production in the ocean, and the sinking flux of this new production results in carbon sequestration. Here, we report that the Amazon River plume supports N 2 fixation far from the mouth and provides important pathways for sequestration of atmospheric CO 2 in the western tropical North Atlantic (WTNA). We calculate that the sinking of carbon fixed by diazotrophs in the plume sequesters 1.7 Tmol of C annually, in addition to the sequestration of 0.6 Tmol of C yr −1 of the new production supported by NO 3 delivered by the river. These processes revise our current understanding that the tropical North Atlantic is a source of 2.5 Tmol of C to the atmosphere [Mikaloff-Fletcher SE, et al. (2007) Inverse estimates of the oceanic sources and sinks of natural CO 2 an...
phytoplankton blooms contributes to marine ecosystem productivity and the annual carbon export. T... more phytoplankton blooms contributes to marine ecosystem productivity and the annual carbon export. The mechanisms underlying the formation, maintenance, and decay of these blooms remain largely unknown; nitrogen fixation, episodic vertical mixing of nutrients, and meso- (<100 km) and submesoscale (<10 km) physical processes are all hypothesized to contribute to bloom dynamics. In addition, zones of convergence in the ocean’s surface layers are known to generate downwelling and/or converging currents that affect plankton distributions. It has been difficult to quantify the importance of these convergence zones in the export flux of particulate organic carbon (POC) in the open ocean. Here we use two high-resolution ocean transects across a pair of mesoscale eddies in the vicinity of Station ALOHA (22 45′N, 158 00′W) to show that horizontal turbulent stirring may have been a dominant control on the spatial distribution of the nitrogen fixing cyanobacterium Trichodesmium spp. Fast re...
A large-volume mesocosm-based nutrient perturbation experiment was conducted off the island of Ha... more A large-volume mesocosm-based nutrient perturbation experiment was conducted off the island of Hawai‘i, USA, to investigate the response of surface ocean phytoplankton communities to the addition of macronutrients, trace metals, and vitamins and to assess the feasibility of using mesocosms in the open ocean. Three free-drifting mesocosms (~60 m3) were deployed: one mesocosm served as a control (no nutrient amendments); a second (termed +P) was amended with nitrate (N), silicate (Si), phosphate (P), and a trace metal + vitamin mixture; and a third (termed -P) was amended with N, Si, and a trace metal + vitamin mixture but no P. These mesocosms were unreplicated due to logistical constraints and hence differences between treatments are qualitative. After 6 d, the largest response of the phytoplankton community was observed in the +P mesocosm, where chlorophyll a and 14C-based primary production were 2-3× greater than in the -P mesocosm and 4-6× greater than in the control. Comparison ...
In the contemporary North Pacific subtropical gyre (NPSG) the extant microbial community is based... more In the contemporary North Pacific subtropical gyre (NPSG) the extant microbial community is based on prokaryotic cells with the cyanobacterium Prochlorococcus dominating the phototrophic component. ...
We provide here a time series of bottle-based, discrete surface (top 25 m of the water column) pa... more We provide here a time series of bottle-based, discrete surface (top 25 m of the water column) particulate carbon concentrations (PC), HPLC-based chlorophyll-a concentrations (Chl), heterotrophic bacteria counts (HBact), and adenosine-5'-triphosphate (ATP) concentrations collected nearly monthly from 2003-2018 at the Hawaii Ocean Time-series Station ALOHA (file: HOT_bottle_data.xlsx). A time series of high resolution (hourly) particulate beam attenuation coefficients are also made available collected at the same station from 2015-2020 (file: HOT_cp_data.xlsx). These data are presented and discussed in a Limnology and Oceanography Letters paper by Henderikx-Freitas, Bjorkman, Karl, and White titled "Constraining growth rates and the ratio of living to non-living particulate carbon using beam attenuation and adenosine-5'-triphosphate at Station ALOHA". See HOT_data_metadata.pdf for additional information.
The marine cyanobacterium Prochlorococcus can utilize glucose as a source of carbon. However, the... more The marine cyanobacterium Prochlorococcus can utilize glucose as a source of carbon. However, the relative importance of inorganic and organic carbon assimilation and the timing of glucose assimilation are still poorly understood in these numerically dominant cyanobacteria. Here we investigated whole microbial community and group-specific primary production and glucose assimilation, using incubations with radioisotopes combined with flow cytometry cell sorting. We also studied changes in the microbial community structure in response to glucose enrichments and analyzed the transcription of Prochlorocccus genes involved in carbon metabolism and photosynthesis.Our results showed a circadian rhythm for glucose assimilation in Prochlorococcus, with maximum assimilation during the midday and minimum at midnight, which was different compared with that of the total microbial community. This suggests that rhythms in glucose assimilation have been adapted in Prochlorococcus to couple the acti...
Publisher Summary The chapter presents the principle and stepwise procedures for the accurate est... more Publisher Summary The chapter presents the principle and stepwise procedures for the accurate estimation of (1) dissolved orthophosphate (HPO 4 2 ; hereafter referred to as “Pi”), soluble reactive P (SRP), total dissolved P (TDP) and particulate P (PP) as minimal constraints on P pool inventories; (2) dissolved and particulate adenosine-5'-triphosphate concentrations (D-ATP and P-ATP, respectively); (3) Pi uptake/regeneration and dissolved organic P (DOP) production rates using radiolabeled Pi ( 32 P or 33 P) precursors; and (4) turnover rate estimation of the α-P and γ-P of intracellular ATP. The latter measurements provide information on microbial growth rate, total energy flux and the biologically available P (BAP) pool. These methods collectively provide a protocol suite that is suitable for an initial study of P dynamics in selected marine habitats.
Biogeochemistry of Marine Dissolved Organic Matter, 2002
... Hawaii I. Introduction II. Terms, Definitions, and Concentration Units III. The Early Years o... more ... Hawaii I. Introduction II. Terms, Definitions, and Concentration Units III. The Early Years of Pelagic Marine P-cycle Research (1884-1955) IV. The Pelagic Marine P-cycle: Key Pools and Processes V. Sampling, Incubation, Storage ...
Analysis of a portion of Vostok ice core number 5G, which is thought to contain frozen water deri... more Analysis of a portion of Vostok ice core number 5G, which is thought to contain frozen water derived from Lake Vostok, Antarctica (a body of liquid water located beneath about 4 kilometers of glacial ice), revealed between 2 × 10 2 and 3 × 10 2 bacterial cells per milliliter and low concentrations of potential growth nutrients. Lipopolysaccharide (a Gram-negative bacterial cell biomarker) was also detected at concentrations consistent with the cell enumeration data, which suggests a predominance of Gram-negative bacteria. At least a portion of the microbial assemblage was viable, as determined by the respiration of carbon-14–labeled acetate and glucose substrates during incubations at 3°C and 1 atmosphere. These accreted ice data suggest that Lake Vostok may contain viable microorganisms.
Proceedings of the National Academy of Sciences, 2008
The fresh water discharged by large rivers such as the Amazon is transported hundreds to thousand... more The fresh water discharged by large rivers such as the Amazon is transported hundreds to thousands of kilometers away from the coast by surface plumes. The nutrients delivered by these river plumes contribute to enhanced primary production in the ocean, and the sinking flux of this new production results in carbon sequestration. Here, we report that the Amazon River plume supports N 2 fixation far from the mouth and provides important pathways for sequestration of atmospheric CO 2 in the western tropical North Atlantic (WTNA). We calculate that the sinking of carbon fixed by diazotrophs in the plume sequesters 1.7 Tmol of C annually, in addition to the sequestration of 0.6 Tmol of C yr −1 of the new production supported by NO 3 delivered by the river. These processes revise our current understanding that the tropical North Atlantic is a source of 2.5 Tmol of C to the atmosphere [Mikaloff-Fletcher SE, et al. (2007) Inverse estimates of the oceanic sources and sinks of natural CO 2 an...
phytoplankton blooms contributes to marine ecosystem productivity and the annual carbon export. T... more phytoplankton blooms contributes to marine ecosystem productivity and the annual carbon export. The mechanisms underlying the formation, maintenance, and decay of these blooms remain largely unknown; nitrogen fixation, episodic vertical mixing of nutrients, and meso- (<100 km) and submesoscale (<10 km) physical processes are all hypothesized to contribute to bloom dynamics. In addition, zones of convergence in the ocean’s surface layers are known to generate downwelling and/or converging currents that affect plankton distributions. It has been difficult to quantify the importance of these convergence zones in the export flux of particulate organic carbon (POC) in the open ocean. Here we use two high-resolution ocean transects across a pair of mesoscale eddies in the vicinity of Station ALOHA (22 45′N, 158 00′W) to show that horizontal turbulent stirring may have been a dominant control on the spatial distribution of the nitrogen fixing cyanobacterium Trichodesmium spp. Fast re...
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