Abstract:

Two research cruises, one in 2012 and one in 2013, were conducted in the Gulf of Mexico to continue to monitor the microbial and planktonic communities and to assess rates of particle flux and the rates of removal of PAHs from the system via this process and accumulation of PAHs in bottom sediments. The bacterial production experiments aim to quantify the amount of bacterial biomass produced at different locations within the Gulf of Mexico. The methods are based on using radioisotope-labeled compounds to quantify rates of DNA synthesis (using thymidine) or protein production (using leucine) by microorganisms (Fuhrman and Azam 1982; Kirchman et al. 1985). These data complement the primary production and respiration experiments; the three sets of data will be combined to quantify microbial processing of organic carbon in the Gulf of Mexico.

Suggested Citation:

Longnecker, Krista. 2015. Bacterial production and bacterial abundance in Gulf of Mexico, spring 2012 and spring 2013.. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7RV0KND

Purpose:

The bacterial production experiments aim to quantify the amount of bacterial biomass produced at different locations within the Gulf of Mexico after the Deepwater Horizon spill.

Data Parameters and Units:

The data include the following parameters (bacterial abundance, bacterial production, and CTD parameters from CTD BTL files): *stationName (station name and cast information) *stnAsTxt (station name only) *Latitude *Longitude *Time (Julian day) *PrDM (pressure in decibar) *DepSM (depth in meters) *T090C (temperature from primary temperature sensor, ºC) *T190C (temperature from secondary temperature sensor, ºC) *Sal00 (salinity, from primary conductivity cell) *Sal11 (salinity, from secondary conductivity cell) *Sbeox0ML_L (dissolved oxygen concentration in ml/l, uncalibrated, from SBE43) *Density00 (density, from primary sensors) *Density11 (density, from secondary sensors) *FlSP (fluorescence, in volts) *Par (PAR/Irradiance from Biospherical/Licor sensor) *Scan (CTD scan number for the discrete sample collection) *Leu_mean (Mean bacterial production, based on leucine incorporation, in moles leucine L-1 hr-1) *Leu_SD (Standard deviation of bacterial production, based on leucine incorporation, in moles leucine L-1 hr-1) *Tdr_mean (Mean bacterial production, based on thymidine incorporation, in moles thymidine L-1 hr 1) *Tdr_SD (Standard deviation of bacterial production, based on thymidine incorporation, in moles thymidine L-1 hr-1) *NiskinNumber *Bacteria (abundance in cells per ml) *HighNucleicAcid (abundance in cells per ml) *LowNucleicAcid (abundance in cells per ml) *Synechococcus (abundance in cells per ml) *EukPhyto (abundance in cells per ml) *LargeDiatoms (abundance in cells per ml) *Prochlorococcus (abundance in cells per ml) *Cryptophyte (abundance in cells per ml) *Year (2012 or 2013)

Methods:

Bacterial production was assayed using radioisotope-labeled compounds to quantify rates of DNA synthesis (using thymidine) or protein production (using leucine) by microorganisms (Fuhrman and Azam, 1982; Kirchman et al., 1985). Water samples were collected from multiple depths at each station and incubated with 3H-leucine or 3H-thymidine at in situ temperatures. The incubations were stopped by the addition of trichloroacetic acid and frozen until sample processing on land. After processing in the laboratory, the samples were counted on a liquid scintillation counter to quantify the amount of radiolabeled material assimilated; this value is directly related to the amount of carbon assimilated by heterotrophic microorganisms. Fuhrman, J.A. and Azam, F., 1982. Thymidine incorporation as a measure of heterotrophic bacterioplankton production in marine surface waters: Evaluation and field results. Mar. Biol. 66, 109-120. Kirchman, D.L., K'nees, E. and Hodson, R., 1985. Leucine incorporation and its potential as a measure of protein synthesis by bacteria in natural waters. Appl. Environ. Microbiol. 49, 599-607.

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