scholarly journals Nutrient consumption by diatoms in the dark subsurface layer of Funka Bay, Hokkaido, Japan

2022 ◽  
Author(s):  
Sachi Umezawa ◽  
Manami Tozawa ◽  
Yuichi Nosaka ◽  
Daiki Nomura ◽  
Hiroji Onishi ◽  
...  
Keyword(s):  
Surface Waters ◽  
Spring Bloom ◽  
Subsurface Layer ◽  
Observational Evidence ◽  
Surface Mixed Layer ◽  
Substantial Influence ◽  
Nutrient Reduction ◽  
Funka Bay ◽  
Incubation Experiments ◽  
Nutrient Consumption

Abstract. We conducted time-series observations in Funka Bay, Hokkaido, Japan, from 15 February to 14 April 2019. The diatom spring bloom peaked on 4 March and started declining on 15 March. Funka Bay winter water remained below 30-m depth, which was below the surface mixed-layer and dark-zone depths on both dates. At depths of 30–50 m, concentrations of NO3–, PO43–, and Si(OH)4 decreased by half between these dates even in darkness. Incubation experiments using the diatom Thalassiosira nordenskioeldii showed that this diatom could consume nutrients in darkness at substantial rates. We conclude that the nutrient reduction in the subsurface layer (30–50 m) could be explained by dark consumption by diatoms that had been growing in the surface waters and then sank to the subsurface layer. We believe that this is the first study to present observational evidence for the consumption of the main nutrients by diatoms in the dark subsurface layer during the spring bloom. Nutrient consumption in this layer might have a substantial influence on the primary production during and after the spring bloom.

scholarly journals Supplementary material to "Nutrient consumption by diatoms in the dark subsurface layer of Funka Bay, Hokkaido, Japan"

2022 ◽  
Author(s):  
Sachi Umezawa ◽  
Manami Tozawa ◽  
Yuichi Nosaka ◽  
Daiki Nomura ◽  
Hiroji Onishi ◽  
...  
Keyword(s):  
Subsurface Layer ◽  
Funka Bay ◽  
Nutrient Consumption ◽  
Supplementary Material

Behavior of Cu, Ni and Cd during nutrient depletion in a spring bloom in Funka Bay

1998 ◽  
Vol 54 (6) ◽  
pp. 619-627 ◽  
Author(s):  
Isao Kudo ◽  
Katsuhiko Matsunaga
Keyword(s):  
Spring Bloom ◽  
Nutrient Depletion ◽  
Funka Bay

scholarly journals Evidence for methane production by the marine algae <i>Emiliania huxleyi</i>

2016 ◽  
Vol 13 (10) ◽  
pp. 3163-3174 ◽  
Author(s):  
Katharina Lenhart ◽  
Thomas Klintzsch ◽  
Gerald Langer ◽  
Gernot Nehrke ◽  
Michael Bunge ◽  
...  
Keyword(s):  
Surface Waters ◽  
Marine Algae ◽  
Methanogenic Archaea ◽  
Emiliania Huxleyi ◽  
Algal Culture ◽  
Radiation Balance ◽  
Surface Mixed Layer ◽  
Large Lakes ◽  
Isotope Label ◽  
Ch4 Production

Abstract. Methane (CH4), an important greenhouse gas that affects radiation balance and consequently the earth's climate, still has uncertainties in its sinks and sources. The world's oceans are considered to be a source of CH4 to the atmosphere, although the biogeochemical processes involved in its formation are not fully understood. Several recent studies provided strong evidence of CH4 production in oxic marine and freshwaters, but its source is still a topic of debate. Studies of CH4 dynamics in surface waters of oceans and large lakes have concluded that pelagic CH4 supersaturation cannot be sustained either by lateral inputs from littoral or benthic inputs alone. However, regional and temporal oversaturation of surface waters occurs frequently. This comprises the observation of a CH4 oversaturating state within the surface mixed layer, sometimes also termed the "oceanic methane paradox". In this study we considered marine algae as a possible direct source of CH4. Therefore, the coccolithophore Emiliania huxleyi was grown under controlled laboratory conditions and supplemented with two 13C-labeled carbon substrates, namely bicarbonate and a position-specific 13C-labeled methionine (R-S-13CH3). The CH4 production was 0.7 µg particular organic carbon (POC) g−1 d−1, or 30 ng g−1 POC h−1. After supplementation of the cultures with the 13C-labeled substrate, the isotope label was observed in headspace CH4. Moreover, the absence of methanogenic archaea within the algal culture and the oxic conditions during CH4 formation suggest that the widespread marine algae Emiliania huxleyi might contribute to the observed spatially and temporally restricted CH4 oversaturation in ocean surface waters.

Behavior and dynamic balance of manganese during spring bloom in Funka Bay, Japan

1992 ◽  
Vol 40 (3-4) ◽  
pp. 273-289 ◽  
Author(s):  
Isao Kudo ◽  
Tomoyuki Ohyama ◽  
Shigeto Nakabayashi ◽  
Kenshi Kuma ◽  
Katsuhiko Matsunaga
Keyword(s):  
Spring Bloom ◽  
Dynamic Balance ◽  
Funka Bay

Photosynthesis, respiration, and stable isotopes of oxygen in a large oligotrophic lake (Lake Erie, USA–Canada)

2008 ◽  
Vol 65 (11) ◽  
pp. 2320-2331 ◽  
Author(s):  
Xin Wang ◽  
David Depew ◽  
Sherry Schiff ◽  
Ralph E.H. Smith
Keyword(s):  
Steady State ◽  
Lake Erie ◽  
Temporal Variations ◽  
State Model ◽  
Surface Mixed Layer ◽  
Lake Metabolism ◽  
Dual Isotope ◽  
Incubation Experiments ◽  
Steady State Model ◽  
Nonsteady State

Dissolved oxygen (DO) concentration, isotopic composition (18:16O), and respiratory fractionation (αr) were measured in the east basin of Lake Erie to determine the patterns of planktonic photosynthesis (P) and respiration (R) and to assess a dual isotope, steady-state model for P/R ratios. Values of αr varied significantly between months but averaged close to a widely accepted norm for planktonic respiration (0.982). Isotope dynamics in situ predicted that 33%–53% of hypolimnetic oxygen consumption was by the sediments, consistent with previous knowledge. Except during fall turnover, DO was generally above, and 18:16O below, atmospheric equilibrium in the surface mixed layer (SML), suggesting P/R is usually >1 and agreeing with independent estimates by incubation experiments. P/R ratios calculated from the oxygen isotope model were often inconsistent with the DO and 18:16O data, likely because of uncertainties in αr and nonsteady-state conditions in the SML. The autumnal transition to P/R < 1 was captured better in the DO and 18:16O data than in the incubation experiments. Despite problems with the steady-state model, the isotope data were able to reveal spatial and temporal variations in lake metabolism and indicated a strong autochthonous basis for community metabolism in the SML.

Modeling of the spring bloom in Funka Bay, Japan

2001 ◽  
Vol 21 (5) ◽  
pp. 473-494 ◽  
Author(s):  
Tomonori Azumaya ◽  
Yutaka Isoda ◽  
Shinichiro Noriki
Keyword(s):  
Spring Bloom ◽  
Funka Bay

scholarly journals Ikaite crystals in melting sea ice – implications for <i>p</i>CO<sub>2</sub> and pH levels in Arctic surface waters

2012 ◽  
Vol 6 (2) ◽  
pp. 1015-1035 ◽  
Author(s):  
S. Rysgaard ◽  
R. N. Glud ◽  
K. Lennert ◽  
M. Cooper ◽  
N. Halden ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Waters ◽  
Elevated Temperatures ◽  
Co2 Exchange ◽  
The Arctic ◽  
Co2 Uptake ◽  
Surface Mixed Layer ◽  
Chemical Transformations ◽  
X Ray Diffraction ◽  
Antarctic Sea Ice

Abstract. A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (CaCO3·6H2O) in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from an actively melting 1.7 km2 (0.5–1 m thick) drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures gradually disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice flow thickness by ca. 0.2 m per week and resulted in an estimated 1.6 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 11 mmol m−2 sea ice d−1 or to 3.5 ton km−2 ice floe week−1.

scholarly journals Validation of the Thorpe scale-derived vertical diffusivities against microstructure measurements in the Kerguelen region

2014 ◽  
Vol 11 (8) ◽  
pp. 12137-12157 ◽  
Author(s):  
Y.-H. Park ◽  
J.-H. Lee ◽  
I. Durand ◽  
C.-S. Hong
Keyword(s):  
Surface Waters ◽  
Water Layer ◽  
Polar Front ◽  
Surface Mixed Layer ◽  
Kerguelen Islands ◽  
Seasonal Thermocline ◽  
Thorpe Scale ◽  
Microstructure Measurements ◽  
High Degree ◽  
O 10

Abstract. The Thorpe scale is an energy containing vertical overturning scale of large eddies associated with shear generated turbulence. We make here indirect estimates of vertical diffusivities from the Thorpe scale method in the Polar Front region east of the Kerguelen Islands based on fine scale density profiles gathered during the 2011 KEOPS2 cruise. These are validated in comparison with diffusivities estimated from the turbulence dissipation rate directly measured via a TurboMAP microprofiler. The results are sensitive to the choice of the diffusivity parameterization and the Gargett and Garner's (2008) overturn ratio Ro, with the optimal results showing an agreement within a factor of 4, on average, having been obtained from the parameterization by Shih et al. (2005) and the Ro = 0.25 criterion. The Thorpe scale-derived diffusivities in the KEOPS2 region show a high degree of spatial variability, ranging from a canonical value of O(10−5 m2 s−1) in the Winter Water layer and in the Subantarctic surface waters immediately north of the Polar Front to a high value of O(10−4 m2 s−1) in the seasonal thermocline just below the surface mixed layer. The latter values are found especially over the shallow plateau southeast of the Kerguelen Islands and in the Antarctic surface waters associated with the Polar Front attached to the escarpment northeast of the islands.

scholarly journals Trace chemical species in marine incubation experiments, part A. Experiment design and bacterial abundance control extracellular H<sub>2</sub>O<sub>2</sub> concentrations

2018 ◽  
Author(s):  
Mark J. Hopwood ◽  
Nicolas Sanchez ◽  
Despo Polyviou ◽  
Øystein Leiknes ◽  
Julian Gallego-Urrea ◽  
...  
Keyword(s):  
Large Scale ◽  
Bacterial Abundance ◽  
Skeletonema Costatum ◽  
Incident Light ◽  
Chemical Species ◽  
Experiment Design ◽  
H2o2 Production ◽  
Surface Mixed Layer ◽  
Incubation Experiments ◽  
Microbial Groups

Abstract. The extracellular concentration of H2O2 in surface aquatic environments is controlled by a balance between photochemical production and the microbial synthesis of catalase and peroxidase enzymes to remove H2O2 from solution. In any kind of incubation experiment, the formation rates and equilibrium concentrations of ROS may be sensitive to both the experiment design (particularly to the regulation of incident light) and the abundance of different microbial groups (as both cellular H2O2 production and catalase/peroxidase enzyme production rates differ between species). Whilst there are extensive measurements of photochemical H2O2 formation rates and the distribution of H2O2 in the marine environment, it is poorly constrained how different microbial groups affect extracellular H2O2 concentrations, how comparable extracellular H2O2 concentrations within large scale incubation experiments are to those observed in the surface-mixed layer, and to what extent a miss-match with environmentally relevant concentrations of ROS in incubations could influence biological processes differently to what would be observed in nature. Here we show that both experiment design and bacterial abundance consistently exert control on extracellular H2O2 concentrations across a range of incubation experiments in diverse marine environments. During 4 large scale (> 1000 L) mesocosm experiments (in Gran Canaria, the Mediteranean, Patagonia and Svalbard) most experimental factors appeared to exert only minor, or no, direct effect on H2O2 concentrations. For example, in 3 of 4 experiments where pH was manipulated (to 0.4–0.5 below ambient pH) no significant change was evident in extracellular H2O2 concentrations relative to controls. An influence was sometimes inferred from zooplankton density, but not consistently between different incubation experiments and no change in H2O2 was evident in controlled experiments using different densities of the copepod Calanus finmarchichus grazing on the diatom Skeletonema costatum (

scholarly journals A comparison of biogenic iron quotas during a diatom spring bloom using multiple approaches

2012 ◽  
Vol 9 (2) ◽  
pp. 667-687 ◽  
Author(s):  
A. L. King ◽  
S. A. Sañudo-Wilhelmy ◽  
P. W. Boyd ◽  
B. S. Twining ◽  
S. W. Wilhelm ◽  
...  
Keyword(s):  
Single Cell ◽  
Inductively Coupled Plasma ◽  
Spring Bloom ◽  
Biogenic Elements ◽  
Surface Mixed Layer ◽  
Inductively Coupled ◽  
General Decline ◽  
Sampling Protocols ◽  
Lagrangian Drifter ◽  
Radioisotope Uptake

Abstract. Biogenic Fe quotas were determined using three distinct techniques on samples collected concurrently in the subtropical Pacific Ocean east of New Zealand. Fe quotas were measured using radioisotope uptake experiments (24 h incubation), bulk filtration and analysis by inductively-coupled plasma mass spectrometer (ICPMS), and single-cell synchrotron x-ray fluorescence (SXRF) analysis over a sixteen-day period (year days 263 to 278 of 2008) during a quasi-Lagrangian drifter experiment that tracked the evolution of the annual spring diatom bloom within a counter-clockwise open-ocean eddy. Overall, radioisotope uptake-determined Fe quotas (washed with oxalate reagent to remove extracellular Fe) were the lowest (0.5–1.0 mmol Fe:mol P; 4–8 μmol Fe:mol C), followed by single-cell Fe quotas (2.3–7.5 mmol Fe:mol P; 17–57 μmol Fe:mol C), and the highest and most variable quotas were from the bulk filtration ICPMS approach that used the oxalate reagent wash, corrected for lithogenic Fe using Al (0.8–21 mmol Fe:mol P; 4–136 μmol Fe:mol C). During the evolution of the spring bloom within the eddy (year days 263 to 272), the surface mixed layer inventories of particulate biogenic elements (C, N, P, Si) and chlorophyll increased while Fe quotas estimated from all three approaches exhibited a general decline. After the onset of the bloom decline, the drogued buoys exited the eddy center (days 273 to 277). Fe quotas returned to pre-bloom values during this part of the study. Our standardized and coordinated sampling protocols reveal the general observed trend in Fe quotas: ICPMS > SXRF > radioisotope uptake. We discuss the inherent differences between the techniques and argue that each technique has its individual merits and uniquely contributes to the characterization of the oceanic particulate Fe pool.

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