Scranton Mary I.

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Methane production in the waters off Walvis Bay

(Woods Hole Oceanographic Institution, 1978-09) Scranton, Mary I. ; Farrington, John W.

Nine stations were occupied in the vicinity of Walvis Bay, Namibia, during a detailed study of the distribution of methane in this highly productive coastal environment. The principal features of the observed coastal methane distribution included ( I) excess methane in the mixed layer of from 2 times to greater than 300 times solubility equilibrium with the atmosphere, (2) a subsurface maximum, located in the top of the pycnocline, at which concentrations ranged from 2.6 to 440 times solubility equilibrium. (3) an intermediate depth minimum, where concentrations were comparable to those offshore at similar depths and which we attribute to the influence of onshore movement of subsurface offshore water, and (4) a bottom maximum, which we attribute to input of methane to the water column from the anoxic sediments in the Walvis Bay area. An attempt was made to identify the relative importance for methane supply to the coastal mixed layer of in situ biological production and of eddy diffusive and advective transport of methane-rich water which has been in contact with the bottom at the coast. Calculations suggest that both in situ production and physical processes are major sources of excess methane for the highly productive coastal surface waters. However, the complicated circulation patterns make quantification extremely difficult.
CARIACO time series individual CTD profiles from B/O Hermano Gines HG93_CARIACO in the CARIACO basin from 1995-2017 (CARIACO project)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-07-17) Muller-Karger, Frank ; Astor, Yrene ; Benitez-Nelson, Claudia ; Buck, Kristen N. ; Fanning, Kent ; Scranton, Mary I. ; Taylor, Gordon T. ; Thunell, Robert C. ; Varela, Ramon ; Capelo, Juan ; Gutierrez, Javier ; Guzman, Laurencia ; Lorenzoni, Laura ; Montes, Enrique ; Rojas, Jaimie ; Rondon, Anadiuska ; Rueda-Roa, Digna

This collection of data comprises all the Individual CTD profiles from the Cariaco basin taken as part of the CARIACO Ocean Time-Series Program from November 1995 to January 2017. These include all the CTD profiles taken during the monthly hydrographic cruises at the CARIACO station (10.50° N, 64.67° W), as well as other CTD profiles from extra legs of the monthly cruises, and few spatial cruises collected in and around the Cariaco basin. CTD’s Salinity and Oxygen where calibrated with in-situ measurements (see Acquisition Description). This dataset is complimentary to the monthly “CTD Composite Profiles” (https://www.bco-dmo.org/dataset/3092), and many fields are very similar to that data-base. The difference with that dataset, is that here we present all the CTD casts for each cruise, the CTD profiles are single (not composite), and the salinity and oxygen profiles were calibrated with in-situ measurements, but fluorescence was no calibrated. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/773146
Time series HPLC pigment data as measured by the NASA Goddard Space Flight Center from B/O Hermano Gines cruises CAR-176 to CAR-232 in the CARIACO basin from 2011-01-11 through 2017-01-12 (CARIACO Ocean Time-Series Program)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-09-27) Muller-Karger, Frank ; Astor, Yrene ; Scranton, Mary I. ; Taylor, Gordon T. ; Thunell, Robert C. ; Troccoli, Luis ; Varela, Ramon

The CARIACO Ocean Time-Series Program (formerly known as CArbon Retention In A Colored Ocean) started on November 1995 (CAR-001) and ended on January 2017 (CAR-232). Throughout the CARIACO time-series, High Performance Liquid Chromatography (HPLC) data was analyzed by four different laboratories: Bermuda Biological Research Station; Mote Marine Laboratory; Horn Point Laboratory; and NASA Goddard Space Flight Center. This package contains the data analyzed at the NASA Goddard Space Flight Center, covering cruises CAR-176 to CAR-232 from 2011-01-11 to 2017-01-12. Some of the parameters analyzed were different along time and along the different laboratories. To keep the continuity of the HPLC time-series analyzed by different laboratories, all the HPLC files have the same units and contain the same number and order of columns/parameters (with “nd” to indicate when a parameter was no determined). Fluorometric Chlorophyll-a and Phaeopigments (measured at Estación de Investigaciones Marinas de Margarita, Fundación La Salle, EDIMAR-FLASA) are also included. HPLC was not analyzed for cruises CAR-069 to CAR-123. A general description of the CARIACO Ocean Time-Series Program can be found at www.imars.usf.edu/cariaco. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/777689
Time series HPLC pigment data as measured by the Bermuda Biological Research Station (BBRS) from B/O Hermano Gines cruises CAR-002 to CAR-030 in the CARIACO basin from 1995-12-13 through 1998-04-21 (CARIACO Ocean Time-Series Program)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-09-27) Muller-Karger, Frank ; Astor, Yrene ; Scranton, Mary I. ; Taylor, Gordon T. ; Thunell, Robert C. ; Troccoli, Luis ; Varela, Ramon

The CARIACO Ocean Time-Series Program (formerly known as CArbon Retention In A Colored Ocean) started on November 1995 (CAR-001) and ended on January 2017 (CAR-232). Throughout the CARIACO time-series, High Performance Liquid Chromatography (HPLC) data was analyzed by four different laboratories: Bermuda Biological Research Station; Mote Marine Laboratory; Horn Point Laboratory; and NASA Goddard Space Flight Center. This package contains the data analyzed at the Bermuda Biological Research Station, covering cruises CAR-002 to CAR-030 from 1995-12-13 to 1998-04-21. Some of the parameters analyzed were different along time and along the different laboratories. To keep the continuity of the HPLC time-series analyzed by different laboratories, all the HPLC files have the same units and contain the same number and order of columns/parameters (with “nd” to indicate when a parameter was no determined). Fluorometric Chlorophyll-a and Phaeopigments (measured at Estación de Investigaciones Marinas de Margarita, Fundación La Salle, EDIMAR-FLASA) are also included. HPLC was not analyzed for cruises CAR-069 to CAR-123. A general description of the CARIACO Ocean Time-Series Program can be found at www.imars.usf.edu/cariaco. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3293
Time-series Niskin-bottle sample data from R/V Hermano Gines cruises in the Cariaco Basin from 1995 through 2017 (CARIACO Ocean Time-Series Program)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-06-07) Muller-Karger, Frank ; Astor, Yrene ; Scranton, Mary I. ; Taylor, Gordon T. ; Thunell, Robert C. ; Varela, Ramon ; Benitez-Nelson, Claudia ; Buck, Kristen N. ; Fanning, Kent ; Capelo, Juan ; Gutierrez, Javier ; Guzman, Laurencia ; Lorenzoni, Laura ; Montes, Enrique ; Rojas, Jaimie ; Rondon, Anadiuska ; Rueda-Roa, Digna ; Tappa, Eric

The CARIACO Ocean Time-Series Program (formerly known as CArbon Retention In A Colored Ocean) started on November 1995 (CAR-001) and ended on January 2017 (CAR-232). Monthly cruises were conducted to the CARIACO station (10.50° N, 64.67° W) onboard the R/V Hermano Ginés of the Fundación La Salle de Ciencias Naturales de Venezuela. During each cruise, a minimum of four hydrocasts were performed to collect a suite of core monthly observations. We conducted separate shallow and deep casts to obtain a better vertical resolution of in-situ Niskin-bottles samples for chemical observations, and for productivity, phytoplankton, and pigment observations. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3093
Time series HPLC pigment data as measured by MOTE Marine Laboratory & Aquarium from B/O Hermano Gines cruises CAR-031 to CAR-068 in the CARIACO basin from 1998-06-09 to 2001-07-10 (CARIACO Ocean Time-Series Program)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-09-27) Muller-Karger, Frank ; Astor, Yrene ; Scranton, Mary I. ; Taylor, Gordon T. ; Thunell, Robert C. ; Troccoli, Luis ; Varela, Ramon

The CARIACO Ocean Time-Series Program (formerly known as CArbon Retention In A Colored Ocean) started on November 1995 (CAR-001) and ended on January 2017 (CAR-232). Throughout the CARIACO time-series, High Performance Liquid Chromatography (HPLC) data was analyzed by four different laboratories: Bermuda Biological Research Station; Mote Marine Laboratory; Horn Point Laboratory; and NASA Goddard Space Flight Center. This package contains the data analyzed at the MOTE Marine Laboratory & Aquarium, covering cruises CAR-031 to CAR-068 from 1998-06-09 to 2001-07-10. Some of the parameters analyzed were different along time and along the different laboratories. To keep the continuity of the HPLC time-series analyzed by different laboratories, all the HPLC files have the same units and contain the same number and order of columns/parameters (with “nd” to indicate when a parameter was no determined). Fluorometric Chlorophyll-a and Phaeopigments (measured at Estación de Investigaciones Marinas de Margarita, Fundación La Salle, EDIMAR-FLASA) are also included. HPLC was not analyzed for cruises CAR-069 to CAR-123. A general description of the CARIACO Ocean Time-Series Program can be found at www.imars.usf.edu/cariaco. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3292
Time series HPLC pigment data as measured by Horn Point Laboratory (HPL) from B/O Hermano Gines cruises CAR-124 to CAR-175 in the CARIACO basin from 2006-07-04 to 2010-12-08 (CARIACO Ocean Time-Series Program)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-09-27) Muller-Karger, Frank ; Astor, Yrene ; Scranton, Mary I. ; Taylor, Gordon T. ; Thunell, Robert C. ; Troccoli, Luis ; Varela, Ramon

The CARIACO Ocean Time-Series Program (formerly known as CArbon Retention In A Colored Ocean) started on November 1995 (CAR-001) and ended on January 2017 (CAR-232). Throughout the CARIACO time-series, High Performance Liquid Chromatography (HPLC) data was analyzed by four different laboratories: Bermuda Biological Research Station; Mote Marine Laboratory; Horn Point Laboratory; and NASA Goddard Space Flight Center. This package contains the data analyzed at Horn Point Laboratory, covering cruises CAR-124 to CAR-175 from 2006-07-04 to 2010-12-08. Some of the parameters analyzed were different along time and along the different laboratories. To keep the continuity of the HPLC time-series analyzed by different laboratories, all the HPLC files have the same units and contain the same number and order of columns/parameters (with “nd” to indicate when a parameter was no determined). Fluorometric Chlorophyll-a and Phaeopigments (measured at Estación de Investigaciones Marinas de Margarita, Fundación La Salle, EDIMAR-FLASA) are also included. HPLC was not analyzed for cruises CAR-069 to CAR-123. A general description of the CARIACO Ocean Time-Series Program can be found at www.imars.usf.edu/cariaco. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3235
Anomalous delta C-13 in particulate organic carbon at the chemoautotrophy maximum in the Cariaco Basin

(Journal of Geophysical Research-Biogeosciences, 2020-01-30) Scranton, Mary I. ; Taylor, Gordon T. ; Thunell, Robert C. ; Muller-Karger, Frank E. ; Astor, Yrene ; Swart, Peter K. ; Edgcomb, Virginia P. ; Pachiadaki, Maria G.

A chemoautotrophy maximum is present in many anoxic basins at the sulfidic layer's upper boundary, but the factors controlling this feature are poorly understood. In 13 of 31 cruises to the Cariaco Basin, particulate organic carbon (POC) was enriched in 13C (δ13CPOC as high as −16‰) within the oxic/sulfidic transition compared to photic zone values (−23 to −26‰). During “heavy” cruises, fluxes of O2 and [NO3− + NO2−] to the oxic/sulfidic interface were significantly lower than during “light” cruises. Cruises with isotopically heavy POC were more common between 2013 and 2015 when suspended particles below the photic zone tended to be nitrogen rich compared to later cruises. Within the chemoautotrophic layer, nitrogen‐rich particles (molar ratio C/N< 10) were more likely to be 13C‐enriched than nitrogen‐poor particles, implying that these inventories were dominated by living cells and fresh detritus rather than laterally transported or extensively decomposed detritus. During heavy cruises, 13C enrichments persisted to 1,300 m, providing the first evidence of downward transport of chemoautotrophically produced POC. Dissolved inorganic carbon assimilation during heavy cruises (n = 3) was faster and occurred deeper than during light cruises (n = 2). Metagenomics data from the chemoautotrophic layer during two cruises support prevalence of microorganisms carrying RuBisCO form II genes, which encode a carbon fixation enzyme that discriminates less against heavy isotopes than most other carbon fixation enzymes, and metatranscriptomics data indicate that higher expression of form II RuBisCO genes during the heavy cruises at depths where essential reactants coexist are responsible for the isotopically heavier POC.
Determining the flux of methane into Hudson Canyon at the edge of methane clathrate hydrate stability

(John Wiley & Sons, 2016-10-13) Weinstein, Alexander ; Navarrete, Luis ; Ruppel, Carolyn D. ; Weber, Thomas C. ; Leonte, Mihai ; Kellermann, Matthias Y. ; Arrington, Eleanor C. ; Valentine, David L. ; Scranton, Mary I. ; Kessler, John D.

Methane seeps were investigated in Hudson Canyon, the largest shelf-break canyon on the northern U.S. Atlantic Margin. The seeps investigated are located at or updip of the nominal limit of methane clathrate hydrate stability. The acoustic identification of bubble streams was used to guide water column sampling in a 32 km2 region within the canyon's thalweg. By incorporating measurements of dissolved methane concentration with methane oxidation rates and current velocity into a steady state box model, the total emission of methane to the water column in this region was estimated to be 12 kmol methane per day (range: 6–24 kmol methane per day). These analyses suggest that the emitted methane is largely retained inside the canyon walls below 300 m water depth, and that it is aerobically oxidized to near completion within the larger extent of Hudson Canyon. Based on estimated methane emissions and measured oxidation rates, the oxidation of this methane to dissolved CO2 is expected to have minimal influences on seawater pH.
The diversity of sulfide oxidation and sulfate reduction genes expressed by the bacterial communities of the Cariaco Basin, Venezuela

(Bentham Open, 2016-08-31) Rodriguez-Mora, Maria J. ; Edgcomb, Virginia P. ; Taylor, Craig D. ; Scranton, Mary I. ; Taylor, Gordon T. ; Chistoserdov, Andrei Y.

Qualitative expression of dissimilative sulfite reductase (dsrA), a key gene in sulfate reduction, and sulfide:quinone oxidoreductase (sqr), a key gene in sulfide oxidation was investigated. Neither of the two could be amplified from mRNA retrieved with Niskin bottles but were amplified from mRNA retrieved by the Deep SID. The sqr and sqr-like genes retrieved from the Cariaco Basin were related to the sqr genes from a Bradyrhizobium sp., Methylomicrobium alcaliphilum, Sulfurovum sp. NBC37-1, Sulfurimonas autotrophica, Thiorhodospira sibirica and Chlorobium tepidum. The dsrA gene sequences obtained from the redoxcline of the Cariaco Basin belonged to chemoorganotrophic and chemoautotrophic sulfate and sulfur reducers belonging to the class Deltaproteobacteria (phylum Proteobacteria) and the order Clostridiales (phylum Firmicutes).
Time series composite CTD profiles from R/V Hermano Ginés cruises in the Cariaco Basin from 1995 through 2017 (CARIACO Ocean Time-Series Program)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-06-06) Muller-Karger, Frank ; Astor, Yrene ; Benitez-Nelson, Claudia ; Scranton, Mary I. ; Taylor, Gordon T. ; Thunell, Robert C. ; Varela, Ramon ; Capelo, Juan ; Guzman, Laurencia ; Lorenzoni, Laura ; Montes, Enrique ; Rojas, Jaimie ; Rueda-Roa, Digna

The CARIACO Ocean Time-Series Program (formerly known as CArbon Retention In A Colored Ocean) started on November 1995 (CAR-001) and ended on January 2017 (CAR-232). Monthly cruises were conducted to the CARIACO station (10.50° N, 64.67° W) onboard the R/V Hermano Ginés of the Fundación La Salle de Ciencias Naturales de Venezuela. During each cruise, a minimum of four hydrocasts were performed to collect a suite of core monthly observations. We conducted separate shallow and deep casts to obtain a better vertical resolution of in-situ Niskin-bottles samples for chemical observations, and for productivity, phytoplankton, and pigment observations. One CTD composite profile was created for each cruise by stitching together the sections of the different cruise's CTD profiles at the depth interval where water samples were obtained. CTD’s Salinity, Oxygen, and Fluorescence where calibrated with in-situ measurements. The composite CTD profiles dataset is a complement of the hydrographic time series data obtained with the Niskin Bottle Samples (https://www.bco-dmo.org/dataset/3093). The following sections describe the methods used in collecting the core observations at the CARIACO station. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3092
The marine geochemistry of methane

(Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1977-08) Scranton, Mary I.

In the highly productive coastal surface waters near Walvis Bay, methane is present in concentrations considerably above those which would be predicted from solubility equilibrium with the atmosphere. A one dimensional diffusive model and a one dimensional horizontal advection diffusion model were used to describe the methane distribution. Evaluation of the model fits to the data suggests that both advective supply of methane-rich coastal waters and in situ biological methane production are important sources for the mixed layer methane excess. The complexity of the hydrographic regime near Walvis Bay makes it impossible to make a quantitative estimate of the rate of methane production. In the less productive Murray-Wilkinson Basin in the Gulf of Maine, a mixed layer methane excess is also observed. Methane concentrations are closely correlated with hydrographic parameters and the source of methane at a middepth maximum appears to be the highly anoxic sediments in the adjoining Franklin Basin. Diffusion of methane from the middepth maximum is probably adequate to maintain the surface methane excess against loss across the air-sea interface. Coastal waters are frequently enriched in methane, and it has been shown that advective supply of these methane-rich waters may be a significant source of methane for the mixed layer near the coast. Thus the widespread occurrence of a methane maximum at the base of the mixed layer in the open ocean, coupled with surface waters typically 30-70% supersaturated with respect to solubility equilbrium, suggests that advective supply of methane might be an important methane source for the open ocean as well. However, a study of the western subtropical Atlantic shows that advective transport can probably supply only a fraction of the methane present in the maximum. Also the loss of methane across the air-sea interface was observed to be twenty times greater than the flux from the maximum. Thus in situ methane production must be very important to the open ocean methane distribution. A series of phytoplankton culture experiments demonstrated that cultures of both Coccolithus huxleyi and Thalassiosira pseudonana produce trace amounts of methane during logarithmic growth. (Because the cultures are highly oxygenated, anaerobic methane bacteria can be neglected as methane sources. However heterotrophic bacteria cannot be excluded as possible sources of methane to the cultures.) After three algal generations, the rate of methane increase closely parallels the growth curve suggesting that the methane is in fact coming from the algae. A methane production rate of 2 x 10-10 nmole methane/viable cell/hr was calculated from the data. This rate is three to four orders of magnitude slower than the rates of oxygen consumption and glutamate and glucose uptake measured by other workers. for algae and bacteria. The methane production rate calculated from the culture experiments is the correct order of magnitude to account for the methane production occurring in the open ocean. Methane is present in quite low concentrations in the deep ocean. By calculating water mass ages from GEOSECS and other data, it is possible to estimate methane consumption rates in the deep sea. Methane consumption is rapid at first (probably greater than 0.06 nmole/l/yr). At depth consumption appears extremely slow. This may be due to the fact that the methane concentrations in the deep sea are so low that methane oxidizing bacteria cannot use methane as a substrate, or due to reduced metabolic activity in the bacteria at the high pressures and low temperatures of the sea floor. Methane is present in very high concentrations in anoxic basins, indicating that methanogenic bacteria are active. However, near the anoxic-oxic interface in both the Black Sea and the Cariaco Trench a one dimensional advection diffusion model predicts that methane consumption is occurring in the anoxic zone. In the Black Sea the methane depletion may be indicative of the presence of rapid methane oxidation near the Bosporus overflow. However in the Cariaco Trench the validity of such an explanation is difficult to evaluate since the overflow process is so poorly understood. A box model for the Trench has been developed which incorporates time dependence and supply of chemical species to the water from the sediments at all depths in the Trench. This model can explain the silica and sulfide data quite well, but methane depletion near the interface, relative to the model predictions, still occurs. Thus either anaerobic methane oxidation or decreased methane production in the sediments must be hypothesized.
Biogeochemistry and microbiology from the R/V Hermano Gines cruises in the Cariaco Basin from 1995 to 2015 (CARIACO Ocean Time-Series Program)

(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-06-07) Scranton, Mary I. ; Taylor, Gordon T. ; Muller-Karger, Frank ; Astor, Yrene ; Varela, Ramon ; Fanning, Kent ; Buck, Kristen N. ; Rojas, Jaimie

Biogeochemistry and microbiology measurements in the Cariaco Basin. Microbiology sampling were conducted during special CARIACO cruises (distinct from the monthly, core sampling, time-series cruises) from November 1995 to November 2015. The specialized microbiology cruises were usually during May and November, and could be opportunistic or process-driven. There were typically at least 2 cruises per year, during which different variables were sampled and at different depths from the standard monthly CARIACO cruises. Bacteria production data were also reported for the microbiology cruises. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/3120

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