AMT3 Picophytoplankton and heterotrophic bacteria abundance (AFC) measurements from CTD bottle samples
Originator's Protocol for Data Acquisition and Analysis
This data originates from analyses of bottle samples taken from 25 CTD casts.
Seawater was collected in Niskin bottles from 10 depths from 2 to 200 m at 25 stations at intervals of 4 o latitude. Two 0.9 ml subsamples from the same sample were pooled in a polypropylene vial, fixed with 0.1-0.3% (final concentration) glutaraldehyde, frozen and kept either in liquid nitrogen or at -30 o C for 1-2 months before they were analysed.
Samples were analysed in a FACSort flow cytometer (Becton Dickinson, Oxford, UK) equipped with a 15 mW laser exciting at 488 nm. Three major gruops of picophytoplankton: Prochlorococcus , Synechococcus and picoeukaryotic cells, were characterised and enumerated using group specific side scatter and orange (585±21 nm) and red (>650 nm) autfluorescence properties. The total concentration of bacteria was measured in samples stained with the fluorochrome TOTO-1 iodide. Further details of the methodology can be found in Zubkov et al. (1998).
References Cited
Zubkov M.V., Sleigh M.A., Tarran G.A., Burkill P.H. and Leakey R.J.G., 1998. Picoplanktonic community structure on an Atlantic transect from 50 o N to 50 o S. Deep Sea Research, Part I, 45:1339-1355.
Instrumentation Description
Not relevant to this data set.
BODC Data Processing Procedures
Data were submitted to BODC in Microsoft Excel spreadsheet format along with the equivalent data from AMT4 and AMT6. The data were saved to the BODC archive with reference SOC030034. Sample metadata were checked against information held in the database- there was one discrepancy, listed below. Metadata provided in the file upon which matching was based were date, latitude/longitude and bottle firing depth. During this cruise station number is equivalent to Julian Day of sampling. The cruise report states that samples were taken from ten depths from the productivity CTD casts. The CTD log shows the first cast of each day being the productivity cast, with the exception of station 269 where the second cast was the productivity cast. All bacteria data is therefore linked to daily cast 1 except for station 269 which was linked to cast 2.
An extra row of data was present in the file at depth 150m for station 280. There is no record of a bottle being fired at this depth neither in the log, nor in the SeaBird bottle file. It was therefore assumed that this sample was taken from the second cast (269CTD2).
Biomass was calculated for each microorganism using the cellular biomass conversion factors (pg C cell -1 ) for each type as listed in the originator's file: 0.011507 for heterotrophic bacteria, 0.028638 for Prochlorococcus , 0.09997 for Synechococcus and 1.5 for picoeukaryotes.
Count (cells ml -1 ) * biomass conversion factor (pg C cell -1 ) = pg C ml -1
This was then divided by 1000 to convert to mg C m -3
Parameter codes defined in BODC parameter dictionary were assigned to the variables. The data were assigned parameter codes defined in BODC parameter dictionary. Data loaded into BODC's database using established BODC data banking procedures.
A parameter mapping table is provided below;
Originator's Parameter | Units | Description | BODC Parameter Code | Units | Comments |
---|---|---|---|---|---|
HetBact - abundance | cells ml -1 | Abundance of Bacteria (ITIS: 202421: WoRMS 6) [Subgroup: heterotrophic] per unit volume of the water body by automated flow cytometry and subtraction of Synechococcus+Prochlorococcus from total bacteria | HBCCAFTX | cells ml -1 | - |
Prochlorococcus - abundance | cells ml -1 | Abundance of Prochlorococcus spp. (ITIS: 610076: WoRMS 345515) per unit volume of the water body by automated flow cytometry | P701A90Z | cells ml -1 | - |
Synechococcus - abundance | cells ml -1 | Abundance of Synechococcus spp. (ITIS: 773: WoRMS 160572) per unit volume of the water body by automated flow cytometry | P700A90Z | cells ml -1 | - |
Picoeukaryotic Algae - abundance | cells ml -1 | Abundance of picoeukaryotic cells per unit volume of the water body by automated flow cytometry | PYEUA00A | cells ml -1 | - |
HetBact - derived biomass | - | Carbon biomass of Bacteria (ITIS: 202421: WoRMS 6) [Subgroup: heterotrophic] per unit volume of the water body by automated flow cytometry and abundance to carbon conversion by unspecified algorithm | HBBMAFTX | mg C m -3 | Biomass derived from abundance and conversion factor provided by data originator. |
Prochlorococcus - derived biomass | - | Carbon biomass of Prochlorococcus spp. (ITIS: 610076: WoRMS 345515) per unit volume of the water body by automated flow cytometry and abundance to carbon conversion by unspecified algorithm | C701A90Z | mg C m -3 | Biomass derived from abundance and conversion factor provided by data originator. |
Synechococcus - derived biomass | - | Carbon biomass of Synechococcus spp. (ITIS: 773: WoRMS 160572) per unit volume of the water body by optical microscopy and abundance to carbon conversion by unspecified algorithm | C700M90Z | mg C m -3 | Biomass derived from abundance and conversion factor provided by data originator. |
Picoeukaryotic Algae - derived biomass | - | Carbon biomass of picoeukaryotic cells per unit volume of the water body by automated flow cytometry and abundance to carbon conversion by unspecified algorithm | CYEUA00A | mg C m -3 | Biomass derived from abundance and conversion factor provided by data originator. |
Data Quality Report
The dataset has been checked by the data originator - any suspect data values were removed from the data set before submission to BODC.
Problem Report
Not relevant to this data set.