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biomass in SYBR Gold-stained samples because both AO and SYBR Gold stain bacteria cells similarly relative to DAPI (unpublished data).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