Bacteria Abundance, Biomass and Chlorophyll: Water Column Samplesa

BG 235 - Methods used for chlorophyll a (chla) analysis and bacteria biomass determination

Core Sampling techniques:

Sampling methods for recovery of chlorophyll a and bacteria from sea ice cores follows those described in
Garrison and Buck (1986)

Recommendations for reporting were used as outlined by: Horner, R. et al.,(1992)

Analytic Techniques:

Chla (mg m^-3):

determined fluorometrically (Turner Designs 10AU Fluorometer) following extraction in 90% acetone (Parsons et al., 1984)
ice core chla corrected to account for chla in filtered sea water (FSW) added to core sections during melting

Bacteria cell abundance (cells m^-3) and biomass (mg C m^-3):

LMG 0106

preserved (0.5% glutaraldehyde) samples stained with 4',6-diamidino-2-phenylindole (DAPI; 0.1 to 0.3% final concentration), filtered through 0.2 mm black, polycarbonate membrane filters, and mounted onto glass microscope slides on the ship (within 24 hours following collection)
bacteria enumerated using epifluorescence microscopy and sized using digital images taken with Image Pro Plus
bacteria biomass determined using cell abundance, cell biovolume (BV; mm³; as determined from mean length and width measurements), and an allometric conversion factor for bacterial carbon per volume specific for DAPI-stained bacteria (cellular carbon = 218 X BV^0.86; Loferer-Krossbacher et al., 1998).
ice core samples corrected for FSW dilution

NBP 0104

preserved (0.5% glutaraldehyde) samples stained with SYBR Gold (0.01% final concentration), filtered through 0.2 mm Anodisc filters (Whatman), and mounted onto glass microscope slides at home institution (~1-2 months following collection)
bacteria enumerated using epifluorescence microscopy and sized using digital images taken with Image Pro Plus
bacteria biomass determined using cell abundance, cell biovolume (BV; mm³), and an allometric conversion factor for bacterial carbon per volume specific for Acridine Orange-stained bacteria (cellular carbon = 89.9 X BV^0.59; Simon and Azam, 1989). Note: an AO-specific carbon per volume conversion factor was used in calculating biomass in SYBR Gold-stained samples because both AO and SYBR Gold stain bacteria cells similarly relative to DAPI (unpublished data).
ice core samples corrected for FSW dilution

Data from LMG0106 (July-August, 2001) added in June 2002.

Updated: April 21, 2006