cruise 
Cruise identifier

unitless 
cruise_id 
ship 
Ship name

unitless 
ship 
tow 
Tow number

unitless 
tow 
date 
Date; format: yyyymmdd

unitless 
date 
time_starttow 
Time at start of tow (UTC); format: HH:MM

unitless 
time 
time_endtow 
Time at end of tow (UTC); format: HH:MM

unitless 
time 
species 
The planktic foraminifer species measured with the following abbreviations: bul = G. bulloides; glu = G. glutinata; hir = G. hirsuta; inc = N. incompta; inf = G. inflata; pac = N. pachyderma; qui = T. quinqueloba; tru = G. truncatulinoides; uni = O. universa

unitless 
taxon_code 
type 
The kind of foraminiferal organic matter (i.e., tissue or shellbound) measured for N isotope composition

unitless 
sample_descrip 
analysis_year 
The year in which foraminifer samples were measured for N isotope composition. The measurement protocol differed slightly between the three analysis sessions (see Methods Section and Supplemental Text S1 of Smart et al. (2020) for more detail).

unitless 
year 
latitude 
Latitude; positive values = North

decimal degrees 
lat 
longitude 
Longitude; positive values = East

decimal degrees 
lon 
depth_tow 
Depth of the tow

meters (m) 
depth 
d15N_foram_avg 
Average d15N. d15N is the nitrogen isotopic composition of a sample expressed in delta notation (d15N in units of per mil, ‰) relative to atmospheric N2, where d15N = {[(15N/14N)sample/(15N/14N)atmN2] – 1} × 1000

per mil vs AIR 
d15N_bio 
d15N_foram_sd 
Standard deviation of d15N_foram_avg

per mil vs AIR 
d15N_bio 
d15N_foram_n 
Number of replicate measurements of d15N_foram_avg

unitless 
num_reps 
indiv_avg 
Average number of individual foraminifer specimens combined to make a measurement

unitless 
num_reps 
indiv_sd 
Standard deviation of indiv_avg

unitless 
num_reps 
indiv_n 
Number of replicate measurements of indiv_avg

unitless 
num_reps 
Ni_avg 
Average nitrogen contents of foraminifera per individual

nanomoles per individual (nmol/indiv) 
N 
Ni_sd 
Standard deviation of Ni_avg

nanomoles per individual (nmol/indiv) 
N 
Ni_n 
Number of replicate measurements of Ni_avg

unitless 
num_reps 
Nw_avg 
Average nitrogen contents of foraminifera per milligram

nanomoles per milligram (nmol/mg) 
N 
Nw_sd 
Standard deviation of Nw_avg

nanomoles per milligram (nmol/mg) 
N 
Nw_n 
Number of replicate measurements of Nw_avg

unitless 
num_reps 
d15N_avg_nitrate 
Average d15N. d15N is the nitrogen isotopic composition of a sample (nitrate only) expressed in delta notation (d15N in units of per mil, ‰) relative to atmospheric N2, where d15N = {[(15N/14N)sample/(15N/14N)atmN2] – 1} × 1000

per mil vs AIR 
dN15_NO3 
conc_avg_nitrate 
Concentration of nitrate in a seawater sample

micromolar (uM) 
NO3 
d15N_avg_nitrate_nitrite 
Average d15N. d15N is the nitrogen isotopic composition of a sample (nitrate+nitrite) expressed in delta notation (d15N in units of per mil, ‰) relative to atmospheric N2, where d15N = {[(15N/14N)sample/(15N/14N)atmN2] – 1} × 1000

per mil vs AIR 
del15N_NO3NO2 
conc_avg_nitrate_nitrite 
Concentration of nitrate+nitrite in a seawater sample

micromolar (uM) 
NO3_NO2 
temperature_ctd 
Temperature measured by CTD

degrees Celsius 
temp 
salinity_ctd 
Salinity measured by CTD

psu 
sal 
oxygen_ctd 
Oxygen measured by CTD

milliliters per liter (ml/l) 
O2 
fluorescence_ctd 
Fluorescence measured by CTD

milligrams per cubic meter (mg/m3) 
fluor 
potdens_calc 
Potential density, calculated from temperature and salinity

kilograms per cubic meter (kg/m3) 
density 
MLD_calc 
Calculated mixed layer depth at each profile station, defined as the closest depth to the surface at which potential density is greater by greater than or equal to 0.03 kg/m3 than the value at a reference depth of 11 m (the shallowest depth common to every CTD station), based on the criterion of de Boyer Montégut et al. (2004).

meters (m) 
depth_mixed_layer 
conc_PON_avg 
Average concentration of PON. PON is the bulk (> 0.3 um) particulate organic nitrogen in surface waters filtered from the ship’s underway intake during the net tow.

micromolar (uM) 
PON 
conc_PON_sd 
Standard deviation of PON concentration

micromolar (uM) 
PON 
conc_PON_n 
Number of replicate measurements of PON concentration

unitless 
num_reps 
d15N_PON_avg 
Average d15N of PON. d15N is the nitrogen isotopic composition of a sample (nitrate only) expressed in delta notation (d15N in units of per mil, ‰) relative to atmospheric N2, where d15N = {[(15N/14N)sample/(15N/14N)atmN2] – 1} × 1000

per mil vs AIR 
d15N 
d15N_PON_sd 
Standard deviation of d15N of PON

per mil vs AIR 
d15N 
d15N_PON_n 
Number of replicate measurements of d15N of PON

unitless 
num_reps 
d15N_zoop_avg 
Average d15N of zooplankton. zoop refers to the bulk (i.e., <1505000 um) zooplankton collected in the same net during the same tow as the foraminifera.

per mil vs AIR 
d15N_bio 
d15N_zoop_se 
Standard error of the d15N of zooplankton

per mil vs AIR 
d15N_bio 
d15N_zoop_n 
Number of replicate measurements of the d15N of zooplankton

unitless 
num_reps 
ISO_DateTime_UTC_starttow 
Date and time (UTC) of start of tow formatted to ISO 8601 standard; format: yyyymmddTHH:MM:SSZ

yyyyMMdd'T'HH:mm:ss'Z' 
ISO_DateTime_UTC 
ISO_DateTime_UTC_endtow 
Date and time (UTC) of end of tow formatted to ISO 8601 standard; format: yyyymmddTHH:MM:SSZ

unitless 
ISO_DateTime_UTC 