Dataset: DON_Oxidation

Name: Dissolved Organic Nitrogen oxidation collected on cruise SAV 17-16 in the South Atlantic Bight aboard the R/V Savannah from 2011 to 2017
Published: 2019-05-08
Keywords: oceans

Cite This Dataset

DOI:10.1575/1912/bco-dmo.767048.1

Spatial Extent: N:31.99 E:-78.765 S:30.3175 W:-81.356

Temporal Extent: 2011-10-04 - 2017-08-19

Project:

Collaborative Research: Direct Oxidation of Organic Nitrogen by Marine Ammonia Oxidizing Organisms (DON Oxidation)

Principal Investigator:

James T. Hollibaugh (University of Georgia, UGA)

Co-Principal Investigator:

Brian N. Popp (University of Hawaii)

BCO-DMO Data Manager:

Mathew Biddle (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2019-05-08

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Data URL:

https://www.bco-dmo.org/dataset/767048/data

Dissolved Organic Nitrogen oxidation collected on cruise SAV 17-16 in the South Atlantic Bight aboard the R/V Savannah from 2011 to 2017

Abstract:

This dataset contains the results of analyses related to ammonia oxidation rates, including oxidation rates of 15N supplied as ammonia, urea, 1,2 diamino ethane, 1,3 diamino propane, 1,4 diamino butane (putrescine), arginine and glutamate. Ancillary data including nutrient concentrations and the abundance of ammonia- and nitrite-oxidizing microorganisms are also reported. The samples analyzed to produce the dataset were collected off the coast of Georgia, USA. Most data were collected on one cruise in August 2017, incidental data from 2011, 2013 and 2016 are also reported.

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Archival Copy

Version Date	Archive	Persistent Identifier	Date Assigned
2019-05-08	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.1575/1912/bco-dmo.767048.1	2019-06-21

Description

Samples were collected from four regions (inshore, midshelf, shelf-break, and oceanic) of the SAB off the Georgia (U.S.A.) coast (Fig. 1; Supporting Information Table S1), with terminology modified from Liu et al. (2018) as follows. “Inshore” stations were within the barrier island complex. “Mid-shelf” stations were outside the barrier island complex to depths < 40 m; due to limited sampling in this zone, no demarcation between “mid-shelf” and “nearshore” stations (as in Liu et al. 2018) was made. “Shelf-break” stations were between 40 m and 500 m depth. While Liu et al. (2018) did not sample waters past the shelf-break, we included deeper stations further offshore (bottom depth > 500 m), which are designated “oceanic” stations. Note that the maximum depth sampled was ≤ 500 m due to equipment limitations.

Inshore samples were collected from a dock at Marsh Landing on the Duplin River (Sapelo Island) and the dock at the Skidaway Institute of Oceanography (Fig. 1). Both inshore sites are salt marsh-dominated estuaries. Water from both sites was sampled from a depth ≤ 1 m and was processed immediately at a nearby laboratory (the University of Georgia Marine Institute on Sapelo Island or onboard the R/V Savannah). Water quality data for Marsh Landing samples were collected as part of the Sapelo Island National Estuarine Research Reserve monitoring program. Relevant data from the Lower Duplin (“LD”) sonde were downloaded from NOAA/CDMO (http://cdmo. baruch.sc.edu/aqs/, last accessed 22 May 2018).

Most SAB samples were collected in August 2017 on the R/V Savannah (cruise SAV-17-16) along transects across the continental shelf and the Gulf Stream and into the western Sargasso Sea, with sampling focused around the shelf-break (Fig. 1). Water from multiple depths was collected using 12-liter Niskin bottles mounted on a rosette equipped with a Sea-Bird SBE25 CTD. Profiles of salinity, temperature, dissolved oxygen, fluorescence, and photosynthetically active radiation (PAR) were collected using the CTD system as described previously (Liu et al. 2018). PAR attenuation (Kd) was calculated from plots of ln(PAR) vs. depth as in Liu et al. (2018). Two additional SAB stations were sampled in October 2011 (described previously by Liu et al. 2015 and Tolar et al. 2017) and are referred to as “2011-4” and “2011-12” (Fig. 1). Environmental data and some of the microbial and rate data from 2011 stations are available in other publications (Liu et al. 2015; Tolar et al. 2017; see BCO-DMO dataset qPCR_Parameters at https://www.bco-dmo.org/dataset/767141).

Acquisition Description

Nutrient analysis

Nutrient samples were filtered through 0.22 μm pore size Durapore GVWP filters (Millipore Sigma) and frozen at −20_C immediately after collection, then stored at −80_C until analysis. Dissolved nitrate (NO3 −), nitrite (NO2 −), phosphate (PO4 3−), and silicate (SiO4 4−) were measured using a Bran and Luebbe AA3 autoanalyzer as described previously (Wilkerson et al. 2015). Ammonium and urea were measured manually using the phenolhypochlorite method (Solórzano 1969) and the diacetylmonoxime method (Rahmatullah and Boyde 1980; Mulvenna and Savidge 1992), respectively.

Oxidation rate measurements

We used 15N-labeled substrates (98–99% 15N, Cambridge Isotope Laboratories) to measure the oxidation of N supplied as NH4+, urea, 1,2-diaminoethane (DAE), 1,3-diaminopropane (DAP), 1,4-diaminobutane (putrescine, PUT), L-glutamic acid (GLU), and L-arginine (ARG). 15N oxidation from NH4+, urea, PUT, and GLU were measured extensively, whereas 15N oxidation from DAE, DAP, and ARG was only measured at a subset of stations (Supporting Information Table S1). GLU and ARG were included as a control for remineralization, as their central roles in microbial metabolism leads to rapid catabolism and NH4 + regeneration (Hollibaugh 1978; Goldman et al. 1987). PUT was used in routine assessments of the oxidation of polyamine-N because it is one of the most consistently detected polyamines in seawater (Nishibori et al. 2001a, 2003; Lu et al. 2014; Liu et al. 2015). Although spermine and spermidine are also common in seawater, 15N-labeled stocks of these polyamines were not commercially available. We measured the oxidation of N from DAE and DAP to investigate the effect of aliphatic chain length (which affects pKa) on oxidation rate.

Duplicate seawater samples contained in 1-liter polycarbonate or 250 mL high density polyethylene (HDPE) bottles wrapped with aluminum foil (to exclude light) were amended with 10–50 nM 15N-labeled substrate. Marsh Landing samples were then placed in an incubator held at in situ temperature in the dark. Samples taken at the Skidaway dock were placed in a mesh bag and immersed at the sea surface at the sampling site. Samples collected at sea were incubated in a tank of flowing surface seawater or in an incubator held at 18 C in the dark. Incubation bottles were sampled for 15N analysis immediately after substrate addition and again after a period of ~ 24 h. 15N samples were subsampled into 50 mL polypropylene centrifuge tubes, frozen at −20_C, and stored at −80_C until analysis. The 15N/14N ratios of the NO3 − plus NO2 − (NOX) pools (δ15NNOx) in the samples were measured using the bacterial denitrifier method to convert NOX to nitrous oxide (N2O; Sigman et al. 2001). The δ15N values of the N2O produced were measured using a Finnigan MAT-252 isotope ratio mass spectrometer coupled with a modified GasBench II interface (Casciotti et al. 2002; Beman et al. 2011; McIlvin and Casciotti 2011). Oxidation rates were calculated using an endpoint model (Beman et al. 2011; Damashek et al. 2016). Since the substrates used were uniformly labeled with 15N, the amount of the N added as the 15N spike (in μM) was multiplied by the number of moles of 15N per mole of substrate, which assumes that all of the N atoms have equal probability of being oxidized. This is likely true for urea, DAE, DAP, and PUT, which are symmetrical molecules, but not likely to be true for ARG, which contains 4 N atoms (one in the α-amino position and three in the guanidine structure of its R-group). Abiotic oxidation of organic N was assessed by measuring 15NOX production following 15N amendment and incubation of 0.22 μm filtered seawater (as described above), and potential metabolism of DON by the denitrifying bacteria used to convert NOX to N2O was checked by adding 15N-labeled substrates into the bacterial cultures prior to mass spectrometry.

We were unable to measure the in situ concentrations of the individual components of DON used in oxidation experiments, other than urea. Based on previous measurements made in the SAB (Lu et al. 2014; Liu et al. 2015), we assumed concentrations of 1 nM and 0.25 nM for DAE, DAP and PUT, and 10 nM and 5 nM for GLU and ARG, at inshore and mid-shelf/shelf-break/oceanic stations, respectively. Rates of polyamine and amino acid oxidation reported below should therefore be considered potential rates, as amendments as low as 10–50 nM are likely to increase substrate concentrations substantially above in situ. Initial substrate 15N activity was calculated using isotope mass balance using the known concentration and 15N activity of the labeled substrates added and assuming the concentrations described above and natural abundance 15N activity (i.e., 0.3663 atom% 15N).

Processing Description

BCO-DMO Processing Notes:
- added conventional header with dataset name, PI name, version date
- modified parameter names to conform with BCO-DMO naming conventions
- converted latitude and longitude values from degrees minutes seconds to degrees and appended a new column (lat, lon).
- converted Date column to ISO convention and appended ISO_Date column for those values.
- replaced "x 10" with "e" to signify power of 10.
- split columns containing "±" into two columns, one for value and one for ± value. Appended "_sd" to the ± value column.
- converted "nan" and blank cells to "nd".

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1538677
NSF Division of Ocean Sciences	OCE-1537995

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
SAV-17-16		2017-08-16	R/V Savannah	James T. Hollibaugh (Chief Scientist)	data info

Instruments

Bran Luebbe AA3 AutoAnalyzer

Supplied Name: Bran and Luebbe AA3 autoanalyzer

Supplied Description:

Dissolved nitrate (NO3 −), nitrite (NO2 −), phosphate (PO4 3−), and silicate (SiO4 4−) were measured using a Bran and Luebbe AA3 autoanalyzer as described previously (Wilkerson et al. 2015).

Instrument Type

Generic Name: Bran Luebbe AA3 AutoAnalyzer

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB04/

Generic Description:

Bran Luebbe AA3 AutoAnalyzer

See the description from the manufacturer.

CTD Sea-Bird 25

Supplied Name: Sea-Bird SBE25 CTD

Supplied Description:

Water from multiple depths was collected using 12-liter Niskin bottles mounted on a rosette equipped with a Sea-Bird SBE25 CTD. Profiles of salinity, temperature, dissolved oxygen, fluorescence, and photosynthetically active radiation (PAR) were collected using the CTD system as described previously (Liu et al. 2018).

Instrument Type

Generic Name: CTD Sea-Bird 25

Acronym: CTD SBE 25

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0040/

Generic Description:

The Sea-Bird SBE 25 SEALOGGER CTD is battery powered and is typically used to record data in memory, eliminating the need for a large vessel, electrical sea cable, and on-board computer. All SBE 25s can also operate in real-time, transmitting data via an opto-isolated RS-232 serial port. Temperature and conductivity are measured by the SBE 3F Temperature sensor and SBE 4 Conductivity sensor (same as those used on the premium SBE 9plus CTD). The SBE 25 also includes the SBE 5P (plastic) or 5T (titanium) Submersible Pump and TC Duct. The pump-controlled, TC-ducted flow configuration significantly reduces salinity spiking caused by ship heave, and in calm waters allows slower descent rates for improved resolution of water column features. Pressure is measured by the modular SBE 29 Temperature Compensated Strain-Gauge Pressure sensor (available in eight depth ranges to suit the operating depth requirement). The SBE 25's modular design makes it easy to configure in the field for a wide range of auxiliary sensors, including optional dissolved oxygen (SBE 43), pH (SBE 18 or SBE 27), fluorescence, transmissivity, PAR, and optical backscatter sensors. More information from Sea-Bird Electronics: http:www.seabird.com.

Isotope-ratio Mass Spectrometer

Supplied Name: Finnigan MAT-252 isotope ratio mass spectrometer

Supplied Description:

The δ15N values of the N2O produced were measured using a Finnigan MAT-252 isotope ratio mass spectrometer coupled with a modified GasBench II interface

Instrument Type

Generic Name: Isotope-ratio Mass Spectrometer

Acronym: IR Mass Spec

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB16/

Generic Description:

The Isotope-ratio Mass Spectrometer is a particular type of mass spectrometer used to measure the relative abundance of isotopes in a given sample (e.g. VG Prism II Isotope Ratio Mass-Spectrometer).

qPCR Thermal Cycler

Supplied Name: C1000 Touch Thermal Cycler

Supplied Description:

All reactions (25 μL total volume) were run in triplicate on a C1000 Touch Thermal Cycler equipped with a CFX96 Real-Time System (Bio- Rad), using either the iTaq Universal Green SYBR Mix (Bio-Rad) or the Platinum qPCR SuperMix-UDG (Thermo Fisher).

Instrument Type

Generic Name: qPCR Thermal Cycler

Acronym: qPCR

Generic Description:

An instrument for quantitative polymerase chain reaction (qPCR), also known as real-time polymerase chain reaction (Real-Time PCR).

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
Cruise_ID	R2R catalog identifier for this cruise	unitless	cruise_id
Sta	Station Identifier. Marsh Landing is on the Duplin River a tidal channel adjacent to Sapelo Island GA.	unitless	station
Region	Arbitratry assignment of stations to zones in the study area identified by location and water properties: I = Inshore; M = midshelf; S = Shelf-break; O = Oceanic	unitless	unknown
depth	Depth sampled in meters	meters	depth
lon	degrees longitude with positive values eastward	decimal degrees	lon
lat	degrees latitude with positive values northward	decimal degrees	lat
Latitude	Latitude in degrees and decimal minutes N	degrees and decimal minutes N	lat
Longitude	Longitude in degrees and decimal minutes W	degrees and decimal minutes W	lon
Date	Sampling date: MM/DD/YYYY	unitless	date
ISO_Date	Date following the ISO convention of YYYY-MM-DD	unitless	date
Bacterial_16S_rRNA	Concentration of genes for Bacteria 16S rRNA determined by qPCR (see qPCR parameter table) in units of copies L-1; Blank Cells = no data; either not sampled or the sample was lost; BLD = Below Limit of Detection. See qPCR parameter table. qPCR data are from single biological replicates; means of triplicate qPCR reactions. Limit of detection is given as copies per mL of template DNA; the limit thus varies by sample depending on volume filtered; extract volume and template volume per per reaction. The limits given are from this sample set assuming the minimum detectable concentration in the template used and 1 uL of template per reaction. They are thus conservative as some reactions were run with 10 uL of template.	copies per liter filtered	unknown
Thaumarchaeal_16S_rRNA	Concentration of genes for Marine Group 1 Archaea (Thaumarchaeota) 16S rRNA determined by qPCR (see qPCR parameter table) in units of copies L-1 Blank Cells = no data either not sampled or the sample was lost; BLD = Below Limit of Detection. See qPCR parameter table. qPCR data are from single biological replicates; means of triplicate qPCR reactions. Limit of detection is given as copies per mL of template DNA; the limit thus varies by sample depending on volume filtered extract volume and template volume per per reaction. The limits given are from this sample set assuming the minimum detectable concentration in the template used and 1 uL of template per reaction. They are thus conservative as some reactions were run with 10 uL of template.	copies per liter filtered	unknown
WCA_amoA	Concentration of genes for Archaeal ammonia monooxygenase subunit A from the Water Column A clade; determined by qPCR (see qPCR parameter table) in units of copies L-1; Blank Cells = no data; either not sampled or the sample was lost; BLD = Below Limit of Detection. See qPCR parameter table. qPCR data are from single biological replicates; means of triplicate qPCR reactions. Limit of detection is given as copies per mL of template DNA; the limit thus varies by sample depending on volume filtered; extract volume and template volume per per reaction. The limits given are from this sample set assuming the minimum detectable concentration in the template used and 1 uL of template per reaction. They are thus conservative as some reactions were run with 10 uL of template.	copies per liter filtered	unknown
WCB_amoA	Concentration of genes for Archaeal ammonia monooxygenase subunit A from the Water Column A clade; determined by qPCR (see qPCR parameter table) in units of copies L-1; "Blank Cells = no data either not sampled or the sample was lost; BLD = Below Limit of Detection. See qPCR parameter table. qPCR data are from single biological replicates means of triplicate qPCR reactions. Limit of detection is given as copies per mL of template DNA; the limit thus varies by sample depending on volume filtered extract volume and template volume per per reaction. The limits given are from this sample set assuming the minimum detectable concentration in the template used and 1 uL of template per reaction. They are thus conservative as some reactions were run with 10 uL of template.	copies per liter filtered	unknown
Nitrospina_16S_rRNA	Concentration of genes for Nitrospina 16S rRNA determined by qPCR (see qPCR parameter table) in units of copies L-1; Blank Cells = no data; either not sampled or the sample was lost; BLD = Below Limit of Detection. See qPCR parameter table. qPCR data are from single biological replicates; means of triplicate qPCR reactions. Limit of detection is given as copies per mL of template DNA; the limit thus varies by sample depending on volume filtered; extract volume and template volume per per reaction. The limits given are from this sample set assuming the minimum detectable concentration in the template used and 1 uL of template per reaction. They are thus conservative as some reactions were run with 10 uL of template.	copies per liter filtered	unknown
N15_added	Final concentration of uniformly 15N labeled test substrates	nanomoles per liter	unknown
Ammonia_Oxidation	Ammonia oxidation rate determined from conversion of 15N-labeled ammonium to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation; our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
Ammonia_Oxidation_sd	Deviation of ammonia oxidation rate determined from conversion of 15N-labeled ammonium to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation; our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_PUT	Oxidation rate of 15N from putrescine (1;4 diamino butane) determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_PUT_sd	Deviation of oxidation rate of 15N from putrescine (1;4 diamino butane) determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_GLU	Oxidation rate of 15N from L-glutamate determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation; our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_GLU_sd	deviation of oxidation rate of 15N from L-glutamate determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation; our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_UREA	Oxidation rate of 15N from urea determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation; our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_UREA_sd	Deviation of oxidation rate of 15N from urea determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation; our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_DAE	Oxidation rate of 15N from 1;2 diamino ethane determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation; our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_DAE_sd	Deviation of oxidation rate of 15N from 1;2 diamino ethane determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation; our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_DAP	Oxidation rate of 15N from 1;3 diamino propane determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation; our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_DAP_sd	Deviation of oxidation rate of 15N from 1;3 diamino propane determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation; our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_ARG	Oxidation rate of 15N from L-arginine determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
N15_ox_from_ARG_sd	Deviation of oxidation rate of 15N from L-arginine determined from conversion of the 15N label to 15N-labeled nitrite plus nitrate; BLD = Below Limit of Detection. 15N data are mean ± S.E.M. of duplicate biological replicates (see Damashek et al. 2018 for details) . Based on a propagation of error calculation our conservative estimate of the precision of 15N measurements ±4‰ for samples at natural abundance and ±5.2‰ for samples artificially enriched with carrier 15N. Our limit of detection was similar to that reported by Santoro et al. (2013) and Beman et al. (2011).	nanomoles per liter per day	unknown
Nitrate	Concentration of nitrate determined by cadmium reduction to nitrite followed by subtraction nitrite already present in the sample; Samples run on an autoanalyzer by Francis Wilkerson's lab at San Francisco State University	micromoles per liter	NO3
Nitrite	Concentration of nitrite determined by autoanalyzer; Samples run on an autoanalyzer by Francis Wilkerson's lab at San Francisco State University	micromoles per liter	NO2
Ammonium	Concentration of ammonium determined by autoanalyzer; Samples run on an autoanalyzer by Francis Wilkerson's lab at San Francisco State University	micromoles per liter	NH4
Urea	Concentration of urea determined by the carboxythiazole method; Samples run in Hollibaugh lab at UGA	micromoles per liter	Urea
Silicate	Concentration of silicate determined by autoanalyzer; Samples run on an autoanalyzer by Francis Wilkerson's lab at San Francisco State University	micromoles per liter	Silicate
Phosphate	Concentration of phosphate determined by autoanalyzer; Samples run on an autoanalyzer by Francis Wilkerson's lab at San Francisco State University	micromoles per liter	unknown
Temperature	Water temperature in centigrade degrees at the depth sampled measured by the environmental sensing package on the samplling rosette	degrees centigrade	temp
Salinity	Salinity at the depth sampled derived from temperature and conductivity measured by the environmental sensing package on the samplling rosette	PSU	sal
Diss_Oxygen	Dissolved oxygen concentration at the depth sampled measured by the environmental sensing package on the samplling rosette	milliliters per liter	O2
Relative_Fluor	Relative Fluorescence measured by the fluorometer on the Niskin rosette sampler converted to mg Chl a L-1 using a regression equation based on extracted chlorophyll data: Chl a = 1.7869RF - 2.2541; R² = 0.83	relative fluorescence	fluor
Atten_Coeff	PAR attenuation coefficient kz in m-1 calculated as the slope of log(PAR) vs depth	per meter	beam_cp
comment	identifier for the comment. comment value a signifies Environmental data, bacterial 16S, thaumarchaeal 16S, AOB amoA, ammonia oxidation, and urea oxidation data were reported previously in Liu et al. (2015) or Tolar et al. (2017);	unitless	comment

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